How does the EBCM communicate with the Yaw Sensor?
02-09-2016, 10:20 PM
#1
How does the EBCM communicate with the Yaw Sensor?
The diagram shows that the sensor is GMLan only and it is route to the brake controller. Anyone have an idea about how the 2 communicate?
Also, anyone have information about how the EBCM transmits its sensors data through the BCM to the suspension controller? Is it essentially raw data or are they packets of sorts marked as data coming from the ebcm?
Also, anyone have information about how the EBCM transmits its sensors data through the BCM to the suspension controller? Is it essentially raw data or are they packets of sorts marked as data coming from the ebcm?
Last edited by HellPhish89; 02-09-2016 at 10:27 PM.
02-12-2016, 06:40 PM
#5
the Yaw/Lateral-G sensor is directly connected by GMLan aka CAN-Bus to the electronic brake control module. I am trying to find how it communicates with and sends data to the EBCM.
02-12-2016, 09:38 PM
#7
Melting Slicks
I am not the expert you're looking for, pretty sure of that, but generally the sensors work on voltages. The computer module (ECBM) sends a reference voltage to the sensor, the senor returns a voltage reading based on conditions at the sensor and the module compares the two. Hopefully someone with a service manual can chime in and say for sure.
02-12-2016, 09:56 PM
#8
The diagram shows that the sensor is GMLan only and it is route to the brake controller. Anyone have an idea about how the 2 communicate?
Also, anyone have information about how the EBCM transmits its sensors data through the BCM to the suspension controller? Is it essentially raw data or are they packets of sorts marked as data coming from the ebcm?
Also, anyone have information about how the EBCM transmits its sensors data through the BCM to the suspension controller? Is it essentially raw data or are they packets of sorts marked as data coming from the ebcm?
The BCM is the brains for the body items like active handle/traction control and ABS, (ecm is the main control for the motor), while the language is written in C for the sensors to communicate back to the BCM on the GM land bus. So depending on the needs of any sensor, it split off to clock cycles speed, and will report back to the BCM on low/ mid/ high speed bus rates.
So in regards to the ECBM, it just driven by the BCM for it's pressure pump and solenoids to function as needed instead.
Hence when the Yaw it telling the BCM that the back end is coming around too far in active handling, the BCM will have the ECM reduce power, and use the ECBM to bring the back end back in line via both the pump and the solenoids.
In the case of just the speed sensors seeing the back tires locked up with the front tires still moving with you hard on the brakes, then the BCM will just use the solenoids alone to stop the rear tires from being lock up under heavy breaking instead.
So really, short of the feed back that the ECBM gives to the BCM to tell it that it fine, its the BCM that is sending a signal to the ECBM to do a specific function when needed instead.
The following 3 users liked this post by Dano523:
02-12-2016, 10:12 PM
#9
Melting Slicks
The BCM is the brains for the body items like active handle/traction control and ABS, (ecm is the main control for the motor), while the language is written in C for the sensors to communicate back to the BCM on the GM land bus. So depending on the needs of any sensor, it split off to clock cycles speed, and will report back to the BCM on low/ mid/ high speed bus rates.
So in regards to the ECBM, it just driven by the BCM for it's pressure pump and solenoids to function as needed instead.
Hence when the Yaw it telling the BCM that the back end is coming around too far in active handling, the BCM will have the ECM reduce power, and use the ECBM to bring the back end back in line via both the pump and the solenoids.
In the case of just the speed sensors seeing the back tires locked up with the front tires still moving with you hard on the brakes, then the BCM will just use the solenoids alone to stop the rear tires from being lock up under heavy breaking instead.
So really, short of the feed back that the ECBM gives to the BCM to tell it that it fine, its the BCM that is sending a signal to the ECBM to do a specific function when needed instead.
So in regards to the ECBM, it just driven by the BCM for it's pressure pump and solenoids to function as needed instead.
Hence when the Yaw it telling the BCM that the back end is coming around too far in active handling, the BCM will have the ECM reduce power, and use the ECBM to bring the back end back in line via both the pump and the solenoids.
In the case of just the speed sensors seeing the back tires locked up with the front tires still moving with you hard on the brakes, then the BCM will just use the solenoids alone to stop the rear tires from being lock up under heavy breaking instead.
So really, short of the feed back that the ECBM gives to the BCM to tell it that it fine, its the BCM that is sending a signal to the ECBM to do a specific function when needed instead.
02-13-2016, 12:43 AM
#10
The BCM is the brains for the body items like active handle/traction control and ABS, (ecm is the main control for the motor), while the language is written in C for the sensors to communicate back to the BCM on the GM land bus. So depending on the needs of any sensor, it split off to clock cycles speed, and will report back to the BCM on low/ mid/ high speed bus rates.
So in regards to the ECBM, it just driven by the BCM for it's pressure pump and solenoids to function as needed instead.
Hence when the Yaw it telling the BCM that the back end is coming around too far in active handling, the BCM will have the ECM reduce power, and use the ECBM to bring the back end back in line via both the pump and the solenoids.
In the case of just the speed sensors seeing the back tires locked up with the front tires still moving with you hard on the brakes, then the BCM will just use the solenoids alone to stop the rear tires from being lock up under heavy breaking instead.
So really, short of the feed back that the ECBM gives to the BCM to tell it that it fine, its the BCM that is sending a signal to the ECBM to do a specific function when needed instead.
So in regards to the ECBM, it just driven by the BCM for it's pressure pump and solenoids to function as needed instead.
Hence when the Yaw it telling the BCM that the back end is coming around too far in active handling, the BCM will have the ECM reduce power, and use the ECBM to bring the back end back in line via both the pump and the solenoids.
In the case of just the speed sensors seeing the back tires locked up with the front tires still moving with you hard on the brakes, then the BCM will just use the solenoids alone to stop the rear tires from being lock up under heavy breaking instead.
So really, short of the feed back that the ECBM gives to the BCM to tell it that it fine, its the BCM that is sending a signal to the ECBM to do a specific function when needed instead.
Wouldnt sensors that transmit data to the BCM be wired to it?
Steering angle, wheel speed, and Lateral-G/Yaw is shown to go to the EBCM. Why would the data transmit to the BCM through the EBCM and then get transmitted back to the EBCM?
02-13-2016, 09:43 AM
#11
The GM bus lan (tan-tn/bk wires) is a full loop through all the main modules.
Hence in and then back out of most of the connectors to the main modules of the car.
On the main modules, they are supplying the through put for the sensors that are tied to each module, and how the BCM sees all the senors in the end.
So no, the gm lan bus does not go in and out of each sensor directly like a daisy chain, but instead, the main modules are router points for the sensors on a the GM main lan bus link instead.
So case and point ( as pointed out in your diagram), the ecbm control board is the router point for the yaw, steering assist/angle, pad senors, with the GM lan bus wires looped through the EBCM board to communicate back to the BCM.
Simply, think of the GM lan bus kind of like this, with the world symbol being the BCM, the blue hubs being the main modules (like the ECBM) , and them the computers being the sensors at the end.
Hence if a single end sensor goes south, it does not take out the entire lan bus instead.
Hence in and then back out of most of the connectors to the main modules of the car.
On the main modules, they are supplying the through put for the sensors that are tied to each module, and how the BCM sees all the senors in the end.
So no, the gm lan bus does not go in and out of each sensor directly like a daisy chain, but instead, the main modules are router points for the sensors on a the GM main lan bus link instead.
So case and point ( as pointed out in your diagram), the ecbm control board is the router point for the yaw, steering assist/angle, pad senors, with the GM lan bus wires looped through the EBCM board to communicate back to the BCM.
Simply, think of the GM lan bus kind of like this, with the world symbol being the BCM, the blue hubs being the main modules (like the ECBM) , and them the computers being the sensors at the end.
Hence if a single end sensor goes south, it does not take out the entire lan bus instead.
Last edited by Dano523; 02-13-2016 at 10:54 AM.
02-13-2016, 10:47 AM
#12
Le Mans Master
Generally, but not in this case. The yaw sensor is complicated enough to justify it's own "control module" that is connected to the serial bus.
Very nice "theory" but almost totally BZZZZT. WRONG!!! From the shop manual:
Yes, almost all of the communications is through serial data packets and the BCM is involved, but only to report what the EBCM is doing. The EBCM is doing all the work of determining when and how much correction to make.
The BCM is the brains for the body items like active handle/traction control and ABS, (ecm is the main control for the motor), while the language is written in C for the sensors to communicate back to the BCM on the GM land bus. So depending on the needs of any sensor, it split off to clock cycles speed, and will report back to the BCM on low/ mid/ high speed bus rates.
So in regards to the ECBM, it just driven by the BCM for it's pressure pump and solenoids to function as needed instead.
Hence when the Yaw it telling the BCM that the back end is coming around too far in active handling, the BCM will have the ECM reduce power, and use the ECBM to bring the back end back in line via both the pump and the solenoids.
In the case of just the speed sensors seeing the back tires locked up with the front tires still moving with you hard on the brakes, then the BCM will just use the solenoids alone to stop the rear tires from being lock up under heavy breaking instead.
So really, short of the feed back that the ECBM gives to the BCM to tell it that it fine, its the BCM that is sending a signal to the ECBM to do a specific function when needed instead.
So in regards to the ECBM, it just driven by the BCM for it's pressure pump and solenoids to function as needed instead.
Hence when the Yaw it telling the BCM that the back end is coming around too far in active handling, the BCM will have the ECM reduce power, and use the ECBM to bring the back end back in line via both the pump and the solenoids.
In the case of just the speed sensors seeing the back tires locked up with the front tires still moving with you hard on the brakes, then the BCM will just use the solenoids alone to stop the rear tires from being lock up under heavy breaking instead.
So really, short of the feed back that the ECBM gives to the BCM to tell it that it fine, its the BCM that is sending a signal to the ECBM to do a specific function when needed instead.
Vehicle Stability Enhancement System (VSES)
The vehicle stability enhancement system (VSES) adds an additional level of vehicle control to the EBCM.
Yaw rate is the rate of rotation about the vehicle's vertical axis. The VSES is activated when the EBCM determines that the desired yaw rate does not match the actual yaw rate as measured by the yaw rate sensor.
The desired yaw rate is calculated from the following parameters:
• The position of the steering wheel
• The speed of the vehicle
• The lateral, or sideways acceleration of the vehicle
The difference between the desired yaw rate and the actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. If the yaw rate error becomes too large, the EBCM attempts to correct the vehicle's yaw motion by applying differential braking to the appropriate wheel. The amount of differential braking applied to the left or right front wheel is based on both the yaw rate error and side slip rate error.
The VSES activations generally occur during aggressive driving, in turns or on bumpy roads without much use of the accelerator pedal. When braking during VSES activation, the pedal pulsations feel different than the ABS pedal pulsations. The brake pedal pulsates at a higher frequency during VSES activation.
The vehicle stability enhancement system (VSES) adds an additional level of vehicle control to the EBCM.
Yaw rate is the rate of rotation about the vehicle's vertical axis. The VSES is activated when the EBCM determines that the desired yaw rate does not match the actual yaw rate as measured by the yaw rate sensor.
The desired yaw rate is calculated from the following parameters:
• The position of the steering wheel
• The speed of the vehicle
• The lateral, or sideways acceleration of the vehicle
The difference between the desired yaw rate and the actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. If the yaw rate error becomes too large, the EBCM attempts to correct the vehicle's yaw motion by applying differential braking to the appropriate wheel. The amount of differential braking applied to the left or right front wheel is based on both the yaw rate error and side slip rate error.
The VSES activations generally occur during aggressive driving, in turns or on bumpy roads without much use of the accelerator pedal. When braking during VSES activation, the pedal pulsations feel different than the ABS pedal pulsations. The brake pedal pulsates at a higher frequency during VSES activation.
The following users liked this post:
HellPhish89 (02-14-2016)
02-14-2016, 10:24 PM
#14
to add to morgan:
ABS Description and Operation
This vehicle is equipped with a Bosch ABS/EBD/TCS/VSES brake system. The electronic brake control module (EBCM) and the brake pressure modulator valve (BPMV) is serviced separately. The BPMV uses a 4 circuit configuration to control hydraulic pressure to each wheel independently.
The following vehicle performance enhancement systems are provided.
Antilock Brake System (ABS)
Bi-State Engine Mount (BSM)
Electronic Brake Distribution (EBD)
Traction Control System (TCS)
Variable Effort Steering (VES)
Vehicle Stability Enhancement System (VSES)
The following components are involved in the operation of the above systems.
ABS pump motor-The ABS pump motor is part of the brake pressure modulator valve. The ABS pump motor is active during ABS, VSES and base brake power assist functions.
System relays-There are two system relays internal to the EBCM. The solenoid relay is energized when the ignition is ON. The ABS pump motor relay supplies a ground path to the ABS pump motor when the EBCM commands the ABS pump motor on. The system relays are non serviceable.
Solenoids-The solenoids are commanded ON and OFF by the EBCM to operate the appropriate valves in the brake pressure modulator valve (BPMV).
Bi-State Engine Mounts solenoid commanded by the EBCM controls vacuum to engine mounts to dampen engine vibration at idle.
Brake booster vacuum sensor-The Brake Booster Vacuum Sensor is a input to EBCM, and operates the ABS pump motor to precharge the brake system.
Variable Effort Steering solenoid commanded by the EBCM to control steering effort based on speed of vehicle.
The BPMV contains the following components:
ABS pump motor and pump
Four inlet valves
Four outlet valves
Two TC isolation valves
Two TC supply valves
A master cylinder pressure sensor
A front low-pressure accumulator
A rear low-pressure accumulator
Lateral accelerometer-The EBCM uses the lateral accelerometer to determine the sideways acceleration of the vehicle. The lateral accelerometer is packaged with the yaw rate sensor as a single component.
Master cylinder pressure sensor-The master cylinder pressure sensor is located within the BPMV. The master cylinder pressure sensor uses a 5-volt reference and generates an output signal proportionate to the hydraulic fluid pressure which is present in the front brake circuit at the master cylinder.
Steering wheel position sensor--The EBCM receives CAN message inputs from the steering wheel position sensor.
Traction control switch-VSES and the engine torque reduction function of TCS are manually disabled or enabled by pressing the traction control switch.
Wheel speed sensors (WSS)-EBCM sends a 12-volt reference voltage signal to each wheel speed sensor. As the wheel spins, the wheel speed sensor produces a square wave DC signal voltage. The wheel speed sensor increases the signal frequency as the wheel speed increases, but does not increase the signal amplitude.
Yaw rate sensor-The EBCM uses the yaw rate sensor to determine the rate of rotation along the vehicle's vertical axis. The yaw rate sensor is packaged with the lateral accelerometer as a single component.
Brake wear sensors-The EBCM monitors the brake pad wear indicators. When the EBCM detects the brake pad to be worn down to an unacceptable level, a warning message will be displayed on the DIC, warning the owner to service the brake pad and rotors
Antilock Brake System (ABS)
When wheel slip is detected during a brake application, an ABS event occurs. During antilock braking, hydraulic pressure in the individual wheel circuits is controlled to prevent any wheel from slipping. A separate hydraulic line and specific solenoid valves are provided for each wheel. The ABS can decrease, hold, or increase hydraulic pressure to each wheel. The ABS does not, however, increase hydraulic pressure above the amount which is transmitted by the master cylinder during braking.
During antilock braking, a series of rapid pulsations is felt in the brake pedal. These pulsations are caused by the rapid changes in position of the individual solenoid valves as the electronic brake control module (EBCM) responds to wheel speed sensor inputs and attempts to prevent wheel slip. These pedal pulsations are present only during antilock braking and stop when normal braking is resumed or when the vehicle comes to a stop. A ticking or popping noise may also be heard as the solenoid valves cycle rapidly. During antilock braking on dry pavement, intermittent chirping noises may be heard as the tires approach slipping. These noises and pedal pulsations are considered normal during antilock operation.
Vehicles equipped with ABS may be stopped by applying normal force to the brake pedal. Brake pedal operation during normal braking is no different than that of previous non-ABS systems. Maintaining a constant force on the brake pedal provides the shortest stopping distance while maintaining vehicle stability. The typical ABS activation sequence is as follows.
Pressure Hold
The EBCM closes the isolation valve and keeps the dump valve closed in order to isolate the slipping wheel when wheel slip occurs. This holds the pressure steady on the brake so that the hydraulic pressure does not increase or decrease.
Pressure Decrease
If a pressure hold does not correct the wheel slip condition, a pressure decrease occurs. The EBCM decreases the pressure to individual wheels during deceleration when wheel slip occurs. The isolation valve is closed and the dump valve is opened. The excess fluid is stored in the accumulator until the pump can return the fluid to the master cylinder or fluid reservoir.
Pressure Increase
After the wheel slip is corrected, a pressure increase occurs. The EBCM increases the pressure to individual wheels during deceleration in order to reduce the speed of the wheel. The isolation valve is opened and the dump valve is closed. The increased pressure is delivered from the master cylinder.
ABS Description and Operation
This vehicle is equipped with a Bosch ABS/EBD/TCS/VSES brake system. The electronic brake control module (EBCM) and the brake pressure modulator valve (BPMV) is serviced separately. The BPMV uses a 4 circuit configuration to control hydraulic pressure to each wheel independently.
The following vehicle performance enhancement systems are provided.
Antilock Brake System (ABS)
Bi-State Engine Mount (BSM)
Electronic Brake Distribution (EBD)
Traction Control System (TCS)
Variable Effort Steering (VES)
Vehicle Stability Enhancement System (VSES)
The following components are involved in the operation of the above systems.
ABS pump motor-The ABS pump motor is part of the brake pressure modulator valve. The ABS pump motor is active during ABS, VSES and base brake power assist functions.
System relays-There are two system relays internal to the EBCM. The solenoid relay is energized when the ignition is ON. The ABS pump motor relay supplies a ground path to the ABS pump motor when the EBCM commands the ABS pump motor on. The system relays are non serviceable.
Solenoids-The solenoids are commanded ON and OFF by the EBCM to operate the appropriate valves in the brake pressure modulator valve (BPMV).
Bi-State Engine Mounts solenoid commanded by the EBCM controls vacuum to engine mounts to dampen engine vibration at idle.
Brake booster vacuum sensor-The Brake Booster Vacuum Sensor is a input to EBCM, and operates the ABS pump motor to precharge the brake system.
Variable Effort Steering solenoid commanded by the EBCM to control steering effort based on speed of vehicle.
The BPMV contains the following components:
ABS pump motor and pump
Four inlet valves
Four outlet valves
Two TC isolation valves
Two TC supply valves
A master cylinder pressure sensor
A front low-pressure accumulator
A rear low-pressure accumulator
Lateral accelerometer-The EBCM uses the lateral accelerometer to determine the sideways acceleration of the vehicle. The lateral accelerometer is packaged with the yaw rate sensor as a single component.
Master cylinder pressure sensor-The master cylinder pressure sensor is located within the BPMV. The master cylinder pressure sensor uses a 5-volt reference and generates an output signal proportionate to the hydraulic fluid pressure which is present in the front brake circuit at the master cylinder.
Steering wheel position sensor--The EBCM receives CAN message inputs from the steering wheel position sensor.
Traction control switch-VSES and the engine torque reduction function of TCS are manually disabled or enabled by pressing the traction control switch.
Wheel speed sensors (WSS)-EBCM sends a 12-volt reference voltage signal to each wheel speed sensor. As the wheel spins, the wheel speed sensor produces a square wave DC signal voltage. The wheel speed sensor increases the signal frequency as the wheel speed increases, but does not increase the signal amplitude.
Yaw rate sensor-The EBCM uses the yaw rate sensor to determine the rate of rotation along the vehicle's vertical axis. The yaw rate sensor is packaged with the lateral accelerometer as a single component.
Brake wear sensors-The EBCM monitors the brake pad wear indicators. When the EBCM detects the brake pad to be worn down to an unacceptable level, a warning message will be displayed on the DIC, warning the owner to service the brake pad and rotors
Antilock Brake System (ABS)
When wheel slip is detected during a brake application, an ABS event occurs. During antilock braking, hydraulic pressure in the individual wheel circuits is controlled to prevent any wheel from slipping. A separate hydraulic line and specific solenoid valves are provided for each wheel. The ABS can decrease, hold, or increase hydraulic pressure to each wheel. The ABS does not, however, increase hydraulic pressure above the amount which is transmitted by the master cylinder during braking.
During antilock braking, a series of rapid pulsations is felt in the brake pedal. These pulsations are caused by the rapid changes in position of the individual solenoid valves as the electronic brake control module (EBCM) responds to wheel speed sensor inputs and attempts to prevent wheel slip. These pedal pulsations are present only during antilock braking and stop when normal braking is resumed or when the vehicle comes to a stop. A ticking or popping noise may also be heard as the solenoid valves cycle rapidly. During antilock braking on dry pavement, intermittent chirping noises may be heard as the tires approach slipping. These noises and pedal pulsations are considered normal during antilock operation.
Vehicles equipped with ABS may be stopped by applying normal force to the brake pedal. Brake pedal operation during normal braking is no different than that of previous non-ABS systems. Maintaining a constant force on the brake pedal provides the shortest stopping distance while maintaining vehicle stability. The typical ABS activation sequence is as follows.
Pressure Hold
The EBCM closes the isolation valve and keeps the dump valve closed in order to isolate the slipping wheel when wheel slip occurs. This holds the pressure steady on the brake so that the hydraulic pressure does not increase or decrease.
Pressure Decrease
If a pressure hold does not correct the wheel slip condition, a pressure decrease occurs. The EBCM decreases the pressure to individual wheels during deceleration when wheel slip occurs. The isolation valve is closed and the dump valve is opened. The excess fluid is stored in the accumulator until the pump can return the fluid to the master cylinder or fluid reservoir.
Pressure Increase
After the wheel slip is corrected, a pressure increase occurs. The EBCM increases the pressure to individual wheels during deceleration in order to reduce the speed of the wheel. The isolation valve is opened and the dump valve is closed. The increased pressure is delivered from the master cylinder.
02-14-2016, 10:25 PM
#15
Electronic Brake Distribution (EBD)
The electronic brake distribution (EBD) is a control system that enhances the hydraulic proportioning function of the mechanical proportioning valve in the base brake system. The EBD control system is part of the operation software in the electronic brake control module (EBCM). The EBD uses active control with existing ABS in order to regulate the vehicle's rear brake pressure.
Brake Pressure Application
The EBCM uses brake pressure application to control traction by transferring torque through the driveline to wheels which are not slipping. The ABS pump motor, and appropriate valve solenoids are commanded ON and OFF to apply brake pressure to the slipping wheels. Brake pressure application is used in an attempt to maintain equal wheel speed sensor (WSS) signals at the driven wheels.
The EBCM does not allow excessive brake pressure application due to the fact that the solenoid coils or the brakes may become overheated, damaging the EBCM or reducing the drivers ability to stop the vehicle. Estimated coil and brake temperatures are determined by a calculation in the EBCM software. Overheated solenoid coils cause all brake pressure application to become disabled and the stability system disabled message to be displayed. Overheated brakes cause brake pressure application during TCS events to disable, yet the VSES remains functional and as long as the engine torque reduction is enabled, there is no indication to the driver when this occurs and no DTC sets.
Vehicle Stability Enhancement System (VSES)
Vehicle stability enhancement system (VSES) provides added stability during aggressive maneuvers. Yaw rate is the rate of rotation about the vehicle's vertical axis. The VSES is activated when the electronic brake control module (EBCM) determines that the desired yaw rate does not match the actual yaw rate as measured by the yaw rate sensor.
The desired yaw rate is calculated by the EBCM using, primarily, the following inputs.
The position of the steering wheel
The speed of the vehicle
The lateral, or sideways acceleration of the vehicle
The difference between the desired yaw rate and the actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. When a yaw rate error is detected, the EBCM attempts to correct the vehicle's yaw motion by applying brake pressure to one or more of the wheels. The amount of brake pressure which is applied varies, depending on the correction required. The engine torque may be reduced also, if it is necessary to slow the vehicle while maintaining stability.
VSES activations generally occur in turns during aggressive driving. When braking during VSES activation, the pedal may pulsate. The brake pedal pulsates at a higher frequency during VSES activation than during ABS activation.
Power-Up Self-Test
The electronic brake control module (EBCM) is able to detect many malfunctions whenever the ignition is ON. However, certain failures cannot be detected unless active diagnostic tests are performed on the components. Shorted solenoid coil or motor windings, for example, cannot be detected until the components are commanded ON by the EBCM. Therefore, a power-up self-test is required at the beginning of each ignition cycle to verify correct operation of components before the various control systems can be enabled. The EBCM performs the first phase of the power-up self-test when the ignition is first turned ON. The system relay, solenoids and the ABS pump motor are commanded ON and OFF to verify proper operation and the EBCM verifies the ability to return the system to base braking in the event of a failure. The master cylinder pressure sensor performs a self-test by sending a series of specific voltage signals to the EBCM, each for a predetermined amount of time. This phase of the power-up self-test may be heard by the driver, depending on how soon the engine is cranked and started after turning ON the ignition. The second phase of the power-up self-test begins when the vehicle is driven at a speed greater than 12 km/h (7.5 mph) and the EBCM has not detected any traction control module (TCS)/vehicle stability enhancement system (VSES) related malfunctions thus far. When the brake switch indicates that the brake is not applied and the master cylinder pressure is detected as being low, the EBCM proceeds with the test. The EBCM isolates all of the wheels by closing the 4 isolation valves. Due to the fact that all of the wheels are isolated during the second phase of the test, the test must be aborted if the brake is applied while the test is being performed. Occasionally, the driver may detect this by experiencing a momentary hard pedal.
VSES Sensors Initialization
The vehicle stability enhancement system (VSES) sensors values may vary slightly due to differences in temperature, sensor mounting, connector resistances, manufacturing, etc. Since VSES is a very sensitive and precise control system, it is imperative that the electronic brake control module (EBCM) be able to accurately equate a given sensor voltage with an actual unit of measurement. For example, the yaw rate signal of one vehicle may be 2.64 volts at +18.0 deg/sec yaw rate while the yaw rate signal of another vehicle may be 2.64 volts at +17.5 deg/sec yaw rate. Therefore, at the beginning of each ignition cycle, the EBCM must perform an initialization procedure to observe how the VSES sensors are correlated with each other and also to determine what each sensor value is when the applicable unit of measurement equals 0. This voltage is referred to as the sensor bias voltage. Although some activation of the VSES system may occur if required to prior to full initialization, the system does not give optimum performance until the sensors are fully initialized.
The following VSES sensors require initialization:
The yaw rate sensor
The lateral accelerometer
The master cylinder pressure sensor
The steering wheel position sensor
When the vehicle speed is greater than 25 km/h (15 mph), full sensor initialization must occur during 3 km (1.8 mi) of driving or 1 km (0.6 mi) of straight and stable driving, whichever occurs first. Although an attempt at initialization may fail due to driving conditions, such as driving on a very winding road, failed initialization is usually caused by a sensor bias voltage which is not within an acceptable range. Often, a DTC sets soon after a failed initialization attempt. The message center displays the stability system disabled message when sensor initialization fails.
The steering angle sensor calibration.The Steering Angle Sensor is calibrated at the assembly plant. If the sensor is replaced, follow the calibration procedure.
ECE 13 Response
The electronic brake control module (EBCM) illuminates the ABS indicator when a malfunction which disables ABS is detected. Usually, the ABS indicator is turned OFF during the following ignition cycle unless the fault is detected during that ignition cycle. However, the setting of a wheel speed sensor related DTC causes the ABS indicator to remain illuminated during the following ignition cycle until the vehicle is operated at a speed greater than 13 km/h (8 mph). This allows the EBCM to verify that no malfunction exists, before turning OFF the ABS indicator. This reaction occurs even if the ABS indicator turns OFF when the scan tool is used to clear the DTCs. When repairing these vehicles, it is important to ensure that the ECE 13 response has occurred and that the ABS indicator does not illuminate after returning the vehicle to the customer. It is also important to verify that ECE 13 is not the cause of an ABS indicator which is illuminated when no DTCs are set, before attempting to diagnose other possible causes.
Driver Information Indicators and Messages
The following indicators are used to inform the driver of several different factors.
Brake Warning Indicator
The instrument panel cluster (IPC) illuminates the brake warning indicator when the following occurs.
The body control module (BCM) detects that the park brake is engaged. The IPC receives a serial data message from the BCM requesting illumination. The brake warning indicator flashes at a rate of approximately twice per second when the park brake is engaged.
The electronic brake control module (EBCM) detects a low brake fluid condition or a base brake pressure differential and sends a serial data message to the IPC requesting illumination.
The IPC performs the bulb check.
The EBCM detects an ABS-disabling malfunction which also disables electronic brake distribution (EBD) and sends a serial data message to the IPC requesting illumination.
ABS Indicator
The IPC illuminates the ABS indicator when the following occurs.
The EBCM detects an ABS-disabling malfunction and sends a serial data message to the IPC requesting illumination.
The IPC performs the bulb check.
The IPC detects a loss of serial data communication with the EBCM.
A DTC is set during the previous ignition cycle which requires an ECE 13 response at the beginning of the current ignition cycle. The EBCM sends a serial data message to the IPC requesting illumination.
Traction Control Off Indicator
The IPC illuminates the traction off indicator when the following occurs.
The EBCM disables engine torque reduction due to a malfunction and sends a serial data message to the IPC requesting illumination.
The driver manually disables VSES and engine torque reduction by pressing the traction control switch. The EBCM sends a serial data message to the IPC requesting illumination.
Stabilitrak Off Message
The message center displays the stabilitrak off message when one or more of the following conditions exists.
The estimated temperature of any solenoid coil exceeds an acceptable limit. The EBCM sends a serial data message to the IPC requesting this display.
The EBCM detects a failed brake switch. The EBCM sends a serial data message to the IPC requesting this display. A DTC sets when this condition exists.
VSES sensor initialization time is excessive. The EBCM sends a serial data message to the IPC requesting this display.
Serial data communication between the EBCM and any of several other control modules is interrupted. The EBCM sends a serial data message to the IPC requesting this display or the IPC displays the message when communication with the EBCM is interrupted.
The PCM is not able to perform engine torque reduction. The EBCM sends a GMLAN message to the IPC requesting this display. DTCs set when this condition exists.
The EBCM detects an excessively low or excessively high ignition voltage. The EBCM sends a GMLAN message to the IPC requesting this display.
Service Stabilitrak Message
The message center displays the service stability system message when any one of many VSES-disabling DTCs is set. The EBCM sends a serial data message to the IPC requesting this display.
Service Traction Control Message
The message center displays the service traction control system message when any one of many traction control - disabling DTCs is set. The EBCM sends a serial data message to the IPC requesting this display.
The electronic brake distribution (EBD) is a control system that enhances the hydraulic proportioning function of the mechanical proportioning valve in the base brake system. The EBD control system is part of the operation software in the electronic brake control module (EBCM). The EBD uses active control with existing ABS in order to regulate the vehicle's rear brake pressure.
Brake Pressure Application
The EBCM uses brake pressure application to control traction by transferring torque through the driveline to wheels which are not slipping. The ABS pump motor, and appropriate valve solenoids are commanded ON and OFF to apply brake pressure to the slipping wheels. Brake pressure application is used in an attempt to maintain equal wheel speed sensor (WSS) signals at the driven wheels.
The EBCM does not allow excessive brake pressure application due to the fact that the solenoid coils or the brakes may become overheated, damaging the EBCM or reducing the drivers ability to stop the vehicle. Estimated coil and brake temperatures are determined by a calculation in the EBCM software. Overheated solenoid coils cause all brake pressure application to become disabled and the stability system disabled message to be displayed. Overheated brakes cause brake pressure application during TCS events to disable, yet the VSES remains functional and as long as the engine torque reduction is enabled, there is no indication to the driver when this occurs and no DTC sets.
Vehicle Stability Enhancement System (VSES)
Vehicle stability enhancement system (VSES) provides added stability during aggressive maneuvers. Yaw rate is the rate of rotation about the vehicle's vertical axis. The VSES is activated when the electronic brake control module (EBCM) determines that the desired yaw rate does not match the actual yaw rate as measured by the yaw rate sensor.
The desired yaw rate is calculated by the EBCM using, primarily, the following inputs.
The position of the steering wheel
The speed of the vehicle
The lateral, or sideways acceleration of the vehicle
The difference between the desired yaw rate and the actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. When a yaw rate error is detected, the EBCM attempts to correct the vehicle's yaw motion by applying brake pressure to one or more of the wheels. The amount of brake pressure which is applied varies, depending on the correction required. The engine torque may be reduced also, if it is necessary to slow the vehicle while maintaining stability.
VSES activations generally occur in turns during aggressive driving. When braking during VSES activation, the pedal may pulsate. The brake pedal pulsates at a higher frequency during VSES activation than during ABS activation.
Power-Up Self-Test
The electronic brake control module (EBCM) is able to detect many malfunctions whenever the ignition is ON. However, certain failures cannot be detected unless active diagnostic tests are performed on the components. Shorted solenoid coil or motor windings, for example, cannot be detected until the components are commanded ON by the EBCM. Therefore, a power-up self-test is required at the beginning of each ignition cycle to verify correct operation of components before the various control systems can be enabled. The EBCM performs the first phase of the power-up self-test when the ignition is first turned ON. The system relay, solenoids and the ABS pump motor are commanded ON and OFF to verify proper operation and the EBCM verifies the ability to return the system to base braking in the event of a failure. The master cylinder pressure sensor performs a self-test by sending a series of specific voltage signals to the EBCM, each for a predetermined amount of time. This phase of the power-up self-test may be heard by the driver, depending on how soon the engine is cranked and started after turning ON the ignition. The second phase of the power-up self-test begins when the vehicle is driven at a speed greater than 12 km/h (7.5 mph) and the EBCM has not detected any traction control module (TCS)/vehicle stability enhancement system (VSES) related malfunctions thus far. When the brake switch indicates that the brake is not applied and the master cylinder pressure is detected as being low, the EBCM proceeds with the test. The EBCM isolates all of the wheels by closing the 4 isolation valves. Due to the fact that all of the wheels are isolated during the second phase of the test, the test must be aborted if the brake is applied while the test is being performed. Occasionally, the driver may detect this by experiencing a momentary hard pedal.
VSES Sensors Initialization
The vehicle stability enhancement system (VSES) sensors values may vary slightly due to differences in temperature, sensor mounting, connector resistances, manufacturing, etc. Since VSES is a very sensitive and precise control system, it is imperative that the electronic brake control module (EBCM) be able to accurately equate a given sensor voltage with an actual unit of measurement. For example, the yaw rate signal of one vehicle may be 2.64 volts at +18.0 deg/sec yaw rate while the yaw rate signal of another vehicle may be 2.64 volts at +17.5 deg/sec yaw rate. Therefore, at the beginning of each ignition cycle, the EBCM must perform an initialization procedure to observe how the VSES sensors are correlated with each other and also to determine what each sensor value is when the applicable unit of measurement equals 0. This voltage is referred to as the sensor bias voltage. Although some activation of the VSES system may occur if required to prior to full initialization, the system does not give optimum performance until the sensors are fully initialized.
The following VSES sensors require initialization:
The yaw rate sensor
The lateral accelerometer
The master cylinder pressure sensor
The steering wheel position sensor
When the vehicle speed is greater than 25 km/h (15 mph), full sensor initialization must occur during 3 km (1.8 mi) of driving or 1 km (0.6 mi) of straight and stable driving, whichever occurs first. Although an attempt at initialization may fail due to driving conditions, such as driving on a very winding road, failed initialization is usually caused by a sensor bias voltage which is not within an acceptable range. Often, a DTC sets soon after a failed initialization attempt. The message center displays the stability system disabled message when sensor initialization fails.
The steering angle sensor calibration.The Steering Angle Sensor is calibrated at the assembly plant. If the sensor is replaced, follow the calibration procedure.
ECE 13 Response
The electronic brake control module (EBCM) illuminates the ABS indicator when a malfunction which disables ABS is detected. Usually, the ABS indicator is turned OFF during the following ignition cycle unless the fault is detected during that ignition cycle. However, the setting of a wheel speed sensor related DTC causes the ABS indicator to remain illuminated during the following ignition cycle until the vehicle is operated at a speed greater than 13 km/h (8 mph). This allows the EBCM to verify that no malfunction exists, before turning OFF the ABS indicator. This reaction occurs even if the ABS indicator turns OFF when the scan tool is used to clear the DTCs. When repairing these vehicles, it is important to ensure that the ECE 13 response has occurred and that the ABS indicator does not illuminate after returning the vehicle to the customer. It is also important to verify that ECE 13 is not the cause of an ABS indicator which is illuminated when no DTCs are set, before attempting to diagnose other possible causes.
Driver Information Indicators and Messages
The following indicators are used to inform the driver of several different factors.
Brake Warning Indicator
The instrument panel cluster (IPC) illuminates the brake warning indicator when the following occurs.
The body control module (BCM) detects that the park brake is engaged. The IPC receives a serial data message from the BCM requesting illumination. The brake warning indicator flashes at a rate of approximately twice per second when the park brake is engaged.
The electronic brake control module (EBCM) detects a low brake fluid condition or a base brake pressure differential and sends a serial data message to the IPC requesting illumination.
The IPC performs the bulb check.
The EBCM detects an ABS-disabling malfunction which also disables electronic brake distribution (EBD) and sends a serial data message to the IPC requesting illumination.
ABS Indicator
The IPC illuminates the ABS indicator when the following occurs.
The EBCM detects an ABS-disabling malfunction and sends a serial data message to the IPC requesting illumination.
The IPC performs the bulb check.
The IPC detects a loss of serial data communication with the EBCM.
A DTC is set during the previous ignition cycle which requires an ECE 13 response at the beginning of the current ignition cycle. The EBCM sends a serial data message to the IPC requesting illumination.
Traction Control Off Indicator
The IPC illuminates the traction off indicator when the following occurs.
The EBCM disables engine torque reduction due to a malfunction and sends a serial data message to the IPC requesting illumination.
The driver manually disables VSES and engine torque reduction by pressing the traction control switch. The EBCM sends a serial data message to the IPC requesting illumination.
Stabilitrak Off Message
The message center displays the stabilitrak off message when one or more of the following conditions exists.
The estimated temperature of any solenoid coil exceeds an acceptable limit. The EBCM sends a serial data message to the IPC requesting this display.
The EBCM detects a failed brake switch. The EBCM sends a serial data message to the IPC requesting this display. A DTC sets when this condition exists.
VSES sensor initialization time is excessive. The EBCM sends a serial data message to the IPC requesting this display.
Serial data communication between the EBCM and any of several other control modules is interrupted. The EBCM sends a serial data message to the IPC requesting this display or the IPC displays the message when communication with the EBCM is interrupted.
The PCM is not able to perform engine torque reduction. The EBCM sends a GMLAN message to the IPC requesting this display. DTCs set when this condition exists.
The EBCM detects an excessively low or excessively high ignition voltage. The EBCM sends a GMLAN message to the IPC requesting this display.
Service Stabilitrak Message
The message center displays the service stability system message when any one of many VSES-disabling DTCs is set. The EBCM sends a serial data message to the IPC requesting this display.
Service Traction Control Message
The message center displays the service traction control system message when any one of many traction control - disabling DTCs is set. The EBCM sends a serial data message to the IPC requesting this display.
02-15-2016, 08:54 AM
#16
Le Mans Master
No, since there is nothing you can do to change it. It either works or you fix the hardware that has failed. You can't easily change the software. If you are really interested, the specifications for it are ISO 11898-1 and ISO 11898-2.
02-15-2016, 11:08 AM
#17
Electronic Brake Distribution (EBD)
The electronic brake distribution (EBD) is a control system that enhances the hydraulic proportioning function of the mechanical proportioning valve in the base brake system. The EBD control system is part of the operation software in the electronic brake control module (EBCM). The EBD uses active control with existing ABS in order to regulate the vehicle's rear brake pressure.
Brake Pressure Application
The EBCM uses brake pressure application to control traction by transferring torque through the driveline to wheels which are not slipping. The ABS pump motor, and appropriate valve solenoids are commanded ON and OFF to apply brake pressure to the slipping wheels. Brake pressure application is used in an attempt to maintain equal wheel speed sensor (WSS) signals at the driven wheels.
The EBCM does not allow excessive brake pressure application due to the fact that the solenoid coils or the brakes may become overheated, damaging the EBCM or reducing the drivers ability to stop the vehicle. Estimated coil and brake temperatures are determined by a calculation in the EBCM software. Overheated solenoid coils cause all brake pressure application to become disabled and the stability system disabled message to be displayed. Overheated brakes cause brake pressure application during TCS events to disable, yet the VSES remains functional and as long as the engine torque reduction is enabled, there is no indication to the driver when this occurs and no DTC sets.
Vehicle Stability Enhancement System (VSES)
Vehicle stability enhancement system (VSES) provides added stability during aggressive maneuvers. Yaw rate is the rate of rotation about the vehicle's vertical axis. The VSES is activated when the electronic brake control module (EBCM) determines that the desired yaw rate does not match the actual yaw rate as measured by the yaw rate sensor.
The desired yaw rate is calculated by the EBCM using, primarily, the following inputs.
The position of the steering wheel
The speed of the vehicle
The lateral, or sideways acceleration of the vehicle
The difference between the desired yaw rate and the actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. When a yaw rate error is detected, the EBCM attempts to correct the vehicle's yaw motion by applying brake pressure to one or more of the wheels. The amount of brake pressure which is applied varies, depending on the correction required. The engine torque may be reduced also, if it is necessary to slow the vehicle while maintaining stability.
VSES activations generally occur in turns during aggressive driving. When braking during VSES activation, the pedal may pulsate. The brake pedal pulsates at a higher frequency during VSES activation than during ABS activation.
Power-Up Self-Test
The electronic brake control module (EBCM) is able to detect many malfunctions whenever the ignition is ON. However, certain failures cannot be detected unless active diagnostic tests are performed on the components. Shorted solenoid coil or motor windings, for example, cannot be detected until the components are commanded ON by the EBCM. Therefore, a power-up self-test is required at the beginning of each ignition cycle to verify correct operation of components before the various control systems can be enabled. The EBCM performs the first phase of the power-up self-test when the ignition is first turned ON. The system relay, solenoids and the ABS pump motor are commanded ON and OFF to verify proper operation and the EBCM verifies the ability to return the system to base braking in the event of a failure. The master cylinder pressure sensor performs a self-test by sending a series of specific voltage signals to the EBCM, each for a predetermined amount of time. This phase of the power-up self-test may be heard by the driver, depending on how soon the engine is cranked and started after turning ON the ignition. The second phase of the power-up self-test begins when the vehicle is driven at a speed greater than 12 km/h (7.5 mph) and the EBCM has not detected any traction control module (TCS)/vehicle stability enhancement system (VSES) related malfunctions thus far. When the brake switch indicates that the brake is not applied and the master cylinder pressure is detected as being low, the EBCM proceeds with the test. The EBCM isolates all of the wheels by closing the 4 isolation valves. Due to the fact that all of the wheels are isolated during the second phase of the test, the test must be aborted if the brake is applied while the test is being performed. Occasionally, the driver may detect this by experiencing a momentary hard pedal.
VSES Sensors Initialization
The vehicle stability enhancement system (VSES) sensors values may vary slightly due to differences in temperature, sensor mounting, connector resistances, manufacturing, etc. Since VSES is a very sensitive and precise control system, it is imperative that the electronic brake control module (EBCM) be able to accurately equate a given sensor voltage with an actual unit of measurement. For example, the yaw rate signal of one vehicle may be 2.64 volts at +18.0 deg/sec yaw rate while the yaw rate signal of another vehicle may be 2.64 volts at +17.5 deg/sec yaw rate. Therefore, at the beginning of each ignition cycle, the EBCM must perform an initialization procedure to observe how the VSES sensors are correlated with each other and also to determine what each sensor value is when the applicable unit of measurement equals 0. This voltage is referred to as the sensor bias voltage. Although some activation of the VSES system may occur if required to prior to full initialization, the system does not give optimum performance until the sensors are fully initialized.
The following VSES sensors require initialization:
The yaw rate sensor
The lateral accelerometer
The master cylinder pressure sensor
The steering wheel position sensor
When the vehicle speed is greater than 25 km/h (15 mph), full sensor initialization must occur during 3 km (1.8 mi) of driving or 1 km (0.6 mi) of straight and stable driving, whichever occurs first. Although an attempt at initialization may fail due to driving conditions, such as driving on a very winding road, failed initialization is usually caused by a sensor bias voltage which is not within an acceptable range. Often, a DTC sets soon after a failed initialization attempt. The message center displays the stability system disabled message when sensor initialization fails.
The steering angle sensor calibration.The Steering Angle Sensor is calibrated at the assembly plant. If the sensor is replaced, follow the calibration procedure.
ECE 13 Response
The electronic brake control module (EBCM) illuminates the ABS indicator when a malfunction which disables ABS is detected. Usually, the ABS indicator is turned OFF during the following ignition cycle unless the fault is detected during that ignition cycle. However, the setting of a wheel speed sensor related DTC causes the ABS indicator to remain illuminated during the following ignition cycle until the vehicle is operated at a speed greater than 13 km/h (8 mph). This allows the EBCM to verify that no malfunction exists, before turning OFF the ABS indicator. This reaction occurs even if the ABS indicator turns OFF when the scan tool is used to clear the DTCs. When repairing these vehicles, it is important to ensure that the ECE 13 response has occurred and that the ABS indicator does not illuminate after returning the vehicle to the customer. It is also important to verify that ECE 13 is not the cause of an ABS indicator which is illuminated when no DTCs are set, before attempting to diagnose other possible causes.
Driver Information Indicators and Messages
The following indicators are used to inform the driver of several different factors.
Brake Warning Indicator
The instrument panel cluster (IPC) illuminates the brake warning indicator when the following occurs.
The body control module (BCM) detects that the park brake is engaged. The IPC receives a serial data message from the BCM requesting illumination. The brake warning indicator flashes at a rate of approximately twice per second when the park brake is engaged.
The electronic brake control module (EBCM) detects a low brake fluid condition or a base brake pressure differential and sends a serial data message to the IPC requesting illumination.
The IPC performs the bulb check.
The EBCM detects an ABS-disabling malfunction which also disables electronic brake distribution (EBD) and sends a serial data message to the IPC requesting illumination.
ABS Indicator
The IPC illuminates the ABS indicator when the following occurs.
The EBCM detects an ABS-disabling malfunction and sends a serial data message to the IPC requesting illumination.
The IPC performs the bulb check.
The IPC detects a loss of serial data communication with the EBCM.
A DTC is set during the previous ignition cycle which requires an ECE 13 response at the beginning of the current ignition cycle. The EBCM sends a serial data message to the IPC requesting illumination.
Traction Control Off Indicator
The IPC illuminates the traction off indicator when the following occurs.
The EBCM disables engine torque reduction due to a malfunction and sends a serial data message to the IPC requesting illumination.
The driver manually disables VSES and engine torque reduction by pressing the traction control switch. The EBCM sends a serial data message to the IPC requesting illumination.
Stabilitrak Off Message
The message center displays the stabilitrak off message when one or more of the following conditions exists.
The estimated temperature of any solenoid coil exceeds an acceptable limit. The EBCM sends a serial data message to the IPC requesting this display.
The EBCM detects a failed brake switch. The EBCM sends a serial data message to the IPC requesting this display. A DTC sets when this condition exists.
VSES sensor initialization time is excessive. The EBCM sends a serial data message to the IPC requesting this display.
Serial data communication between the EBCM and any of several other control modules is interrupted. The EBCM sends a serial data message to the IPC requesting this display or the IPC displays the message when communication with the EBCM is interrupted.
The PCM is not able to perform engine torque reduction. The EBCM sends a GMLAN message to the IPC requesting this display. DTCs set when this condition exists.
The EBCM detects an excessively low or excessively high ignition voltage. The EBCM sends a GMLAN message to the IPC requesting this display.
Service Stabilitrak Message
The message center displays the service stability system message when any one of many VSES-disabling DTCs is set. The EBCM sends a serial data message to the IPC requesting this display.
Service Traction Control Message
The message center displays the service traction control system message when any one of many traction control - disabling DTCs is set. The EBCM sends a serial data message to the IPC requesting this display.
The electronic brake distribution (EBD) is a control system that enhances the hydraulic proportioning function of the mechanical proportioning valve in the base brake system. The EBD control system is part of the operation software in the electronic brake control module (EBCM). The EBD uses active control with existing ABS in order to regulate the vehicle's rear brake pressure.
Brake Pressure Application
The EBCM uses brake pressure application to control traction by transferring torque through the driveline to wheels which are not slipping. The ABS pump motor, and appropriate valve solenoids are commanded ON and OFF to apply brake pressure to the slipping wheels. Brake pressure application is used in an attempt to maintain equal wheel speed sensor (WSS) signals at the driven wheels.
The EBCM does not allow excessive brake pressure application due to the fact that the solenoid coils or the brakes may become overheated, damaging the EBCM or reducing the drivers ability to stop the vehicle. Estimated coil and brake temperatures are determined by a calculation in the EBCM software. Overheated solenoid coils cause all brake pressure application to become disabled and the stability system disabled message to be displayed. Overheated brakes cause brake pressure application during TCS events to disable, yet the VSES remains functional and as long as the engine torque reduction is enabled, there is no indication to the driver when this occurs and no DTC sets.
Vehicle Stability Enhancement System (VSES)
Vehicle stability enhancement system (VSES) provides added stability during aggressive maneuvers. Yaw rate is the rate of rotation about the vehicle's vertical axis. The VSES is activated when the electronic brake control module (EBCM) determines that the desired yaw rate does not match the actual yaw rate as measured by the yaw rate sensor.
The desired yaw rate is calculated by the EBCM using, primarily, the following inputs.
The position of the steering wheel
The speed of the vehicle
The lateral, or sideways acceleration of the vehicle
The difference between the desired yaw rate and the actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. When a yaw rate error is detected, the EBCM attempts to correct the vehicle's yaw motion by applying brake pressure to one or more of the wheels. The amount of brake pressure which is applied varies, depending on the correction required. The engine torque may be reduced also, if it is necessary to slow the vehicle while maintaining stability.
VSES activations generally occur in turns during aggressive driving. When braking during VSES activation, the pedal may pulsate. The brake pedal pulsates at a higher frequency during VSES activation than during ABS activation.
Power-Up Self-Test
The electronic brake control module (EBCM) is able to detect many malfunctions whenever the ignition is ON. However, certain failures cannot be detected unless active diagnostic tests are performed on the components. Shorted solenoid coil or motor windings, for example, cannot be detected until the components are commanded ON by the EBCM. Therefore, a power-up self-test is required at the beginning of each ignition cycle to verify correct operation of components before the various control systems can be enabled. The EBCM performs the first phase of the power-up self-test when the ignition is first turned ON. The system relay, solenoids and the ABS pump motor are commanded ON and OFF to verify proper operation and the EBCM verifies the ability to return the system to base braking in the event of a failure. The master cylinder pressure sensor performs a self-test by sending a series of specific voltage signals to the EBCM, each for a predetermined amount of time. This phase of the power-up self-test may be heard by the driver, depending on how soon the engine is cranked and started after turning ON the ignition. The second phase of the power-up self-test begins when the vehicle is driven at a speed greater than 12 km/h (7.5 mph) and the EBCM has not detected any traction control module (TCS)/vehicle stability enhancement system (VSES) related malfunctions thus far. When the brake switch indicates that the brake is not applied and the master cylinder pressure is detected as being low, the EBCM proceeds with the test. The EBCM isolates all of the wheels by closing the 4 isolation valves. Due to the fact that all of the wheels are isolated during the second phase of the test, the test must be aborted if the brake is applied while the test is being performed. Occasionally, the driver may detect this by experiencing a momentary hard pedal.
VSES Sensors Initialization
The vehicle stability enhancement system (VSES) sensors values may vary slightly due to differences in temperature, sensor mounting, connector resistances, manufacturing, etc. Since VSES is a very sensitive and precise control system, it is imperative that the electronic brake control module (EBCM) be able to accurately equate a given sensor voltage with an actual unit of measurement. For example, the yaw rate signal of one vehicle may be 2.64 volts at +18.0 deg/sec yaw rate while the yaw rate signal of another vehicle may be 2.64 volts at +17.5 deg/sec yaw rate. Therefore, at the beginning of each ignition cycle, the EBCM must perform an initialization procedure to observe how the VSES sensors are correlated with each other and also to determine what each sensor value is when the applicable unit of measurement equals 0. This voltage is referred to as the sensor bias voltage. Although some activation of the VSES system may occur if required to prior to full initialization, the system does not give optimum performance until the sensors are fully initialized.
The following VSES sensors require initialization:
The yaw rate sensor
The lateral accelerometer
The master cylinder pressure sensor
The steering wheel position sensor
When the vehicle speed is greater than 25 km/h (15 mph), full sensor initialization must occur during 3 km (1.8 mi) of driving or 1 km (0.6 mi) of straight and stable driving, whichever occurs first. Although an attempt at initialization may fail due to driving conditions, such as driving on a very winding road, failed initialization is usually caused by a sensor bias voltage which is not within an acceptable range. Often, a DTC sets soon after a failed initialization attempt. The message center displays the stability system disabled message when sensor initialization fails.
The steering angle sensor calibration.The Steering Angle Sensor is calibrated at the assembly plant. If the sensor is replaced, follow the calibration procedure.
ECE 13 Response
The electronic brake control module (EBCM) illuminates the ABS indicator when a malfunction which disables ABS is detected. Usually, the ABS indicator is turned OFF during the following ignition cycle unless the fault is detected during that ignition cycle. However, the setting of a wheel speed sensor related DTC causes the ABS indicator to remain illuminated during the following ignition cycle until the vehicle is operated at a speed greater than 13 km/h (8 mph). This allows the EBCM to verify that no malfunction exists, before turning OFF the ABS indicator. This reaction occurs even if the ABS indicator turns OFF when the scan tool is used to clear the DTCs. When repairing these vehicles, it is important to ensure that the ECE 13 response has occurred and that the ABS indicator does not illuminate after returning the vehicle to the customer. It is also important to verify that ECE 13 is not the cause of an ABS indicator which is illuminated when no DTCs are set, before attempting to diagnose other possible causes.
Driver Information Indicators and Messages
The following indicators are used to inform the driver of several different factors.
Brake Warning Indicator
The instrument panel cluster (IPC) illuminates the brake warning indicator when the following occurs.
The body control module (BCM) detects that the park brake is engaged. The IPC receives a serial data message from the BCM requesting illumination. The brake warning indicator flashes at a rate of approximately twice per second when the park brake is engaged.
The electronic brake control module (EBCM) detects a low brake fluid condition or a base brake pressure differential and sends a serial data message to the IPC requesting illumination.
The IPC performs the bulb check.
The EBCM detects an ABS-disabling malfunction which also disables electronic brake distribution (EBD) and sends a serial data message to the IPC requesting illumination.
ABS Indicator
The IPC illuminates the ABS indicator when the following occurs.
The EBCM detects an ABS-disabling malfunction and sends a serial data message to the IPC requesting illumination.
The IPC performs the bulb check.
The IPC detects a loss of serial data communication with the EBCM.
A DTC is set during the previous ignition cycle which requires an ECE 13 response at the beginning of the current ignition cycle. The EBCM sends a serial data message to the IPC requesting illumination.
Traction Control Off Indicator
The IPC illuminates the traction off indicator when the following occurs.
The EBCM disables engine torque reduction due to a malfunction and sends a serial data message to the IPC requesting illumination.
The driver manually disables VSES and engine torque reduction by pressing the traction control switch. The EBCM sends a serial data message to the IPC requesting illumination.
Stabilitrak Off Message
The message center displays the stabilitrak off message when one or more of the following conditions exists.
The estimated temperature of any solenoid coil exceeds an acceptable limit. The EBCM sends a serial data message to the IPC requesting this display.
The EBCM detects a failed brake switch. The EBCM sends a serial data message to the IPC requesting this display. A DTC sets when this condition exists.
VSES sensor initialization time is excessive. The EBCM sends a serial data message to the IPC requesting this display.
Serial data communication between the EBCM and any of several other control modules is interrupted. The EBCM sends a serial data message to the IPC requesting this display or the IPC displays the message when communication with the EBCM is interrupted.
The PCM is not able to perform engine torque reduction. The EBCM sends a GMLAN message to the IPC requesting this display. DTCs set when this condition exists.
The EBCM detects an excessively low or excessively high ignition voltage. The EBCM sends a GMLAN message to the IPC requesting this display.
Service Stabilitrak Message
The message center displays the service stability system message when any one of many VSES-disabling DTCs is set. The EBCM sends a serial data message to the IPC requesting this display.
Service Traction Control Message
The message center displays the service traction control system message when any one of many traction control - disabling DTCs is set. The EBCM sends a serial data message to the IPC requesting this display.
......seriously ???? Well can you tell me then what the side thrust ratio (at the 50 foot lift off elevation of course) was on the last Saturn Five Rocket launch ???.....
Last edited by windyC6; 02-15-2016 at 02:30 PM.
02-15-2016, 04:30 PM
#18
The following are involved in the operation of the ESC system:
Vehicle speed-The ESCM receives a serial data message for vehicle speed input, and is used to determine the amount of damper control.
Steering wheel position-The ESCM receives a serial data message for steering wheel position input and uses this as an indication of the position and rotation of the steering wheel to determine the amount of damper control.
The ESCM monitors the inputs from the front/rear suspension position sensors, vehicle speed, and steering wheel position. The ESCM calculates the inputs to control 0-100 percent of PWM current to the coil within each strut or shock.
I find it strange that the ESCM only uses 4 sensor inputs. So, we get serial data messages from the yaw/lateral-g/pitch sensor, vehicle speed in the ecm, and steering position from the ebcm. Hmmm.
Next steps are listening to/intercepting the messages and finding suspension physics model that one could plug those 4 inputs into.
And side thrust? Kerbal Space Program tells me that if you rocket isnt going the direction of the velocity vector... you've got problems.
02-15-2016, 05:22 PM
#19
Right now, listening to it is the goal. Here is what I've found so far:
The following are involved in the operation of the ESC system:
Vehicle speed-The ESCM receives a serial data message for vehicle speed input, and is used to determine the amount of damper control.
Steering wheel position-The ESCM receives a serial data message for steering wheel position input and uses this as an indication of the position and rotation of the steering wheel to determine the amount of damper control.
The ESCM monitors the inputs from the front/rear suspension position sensors, vehicle speed, and steering wheel position. The ESCM calculates the inputs to control 0-100 percent of PWM current to the coil within each strut or shock.
I find it strange that the ESCM only uses 4 sensor inputs. So, we get serial data messages from the yaw/lateral-g/pitch sensor, vehicle speed in the ecm, and steering position from the ebcm. Hmmm.
Next steps are listening to/intercepting the messages and finding suspension physics model that one could plug those 4 inputs into.
I cheated and found it in a manual online.
And side thrust? Kerbal Space Program tells me that if you rocket isnt going the direction of the velocity vector... you've got problems.
The following are involved in the operation of the ESC system:
Vehicle speed-The ESCM receives a serial data message for vehicle speed input, and is used to determine the amount of damper control.
Steering wheel position-The ESCM receives a serial data message for steering wheel position input and uses this as an indication of the position and rotation of the steering wheel to determine the amount of damper control.
The ESCM monitors the inputs from the front/rear suspension position sensors, vehicle speed, and steering wheel position. The ESCM calculates the inputs to control 0-100 percent of PWM current to the coil within each strut or shock.
I find it strange that the ESCM only uses 4 sensor inputs. So, we get serial data messages from the yaw/lateral-g/pitch sensor, vehicle speed in the ecm, and steering position from the ebcm. Hmmm.
Next steps are listening to/intercepting the messages and finding suspension physics model that one could plug those 4 inputs into.
I cheated and found it in a manual online.
And side thrust? Kerbal Space Program tells me that if you rocket isnt going the direction of the velocity vector... you've got problems.
