Im having these codes pop up. and how do I fix them?

P1571 H C (ASR desired torque)
TCS no comm.
C1780 H C (Loss of Steering Position Signal)

 

With a FSM. the 1780 is gonna be a whole lot of fun....

http://www.c5help.com/c5_dtc_codes.htm

 

Fsm?

 

Hi George

I'm struggling to find any procedure for the C1780. Its mentioned in the book but its not listed in the DTC list for the RTD.

All I can find is the description:
Steering Position PWM. PWM signal sent to ABS which changes when the steering wheel is turned. The real time damping system uses this signal to determine the shock absorber control levels and will command a firmer setting if the vehicle is turning.

Logically the signal would come from the steering wheel position sensor but again, I can't find any references. Presumably your symptom will be lighter steering in a turn?

Heres the procedure for the other code. I've highlighted the things to check. Looks like it would be good to start at the PCM and EBCM connectors and clean them and check for corrosion or nicks in the wiring.

Document ID# 684616
2001 Chevrolet/Geo Corvette
DTC C1277 or P1571
Circuit Description

The EBCM and the PCM simultaneously control the traction control. The PCM reduces the amount of torque supplied to the drive wheels by retarding spark timing and selectively turning off fuel injectors. The EBCM actively applies the brakes to the front wheels in order to reduce torque.

The EBCM sends a requested torque message via a pulse width modulated (PWM) signal to the PCM. The duty cycle of the signal is used to determine how much engine torque the EBCM is requesting the PCM to deliver. Normal values are between 10 and 90 percent duty cycle. The signal should be at 90 percent when traction control is not active and at lower values during traction control activations. The PCM supplies a pull up voltage of 5 volts that the EBCM switches to ground to create the signal.

The PCM sends a delivered torque message via a pulse width modulated (PWM) signal to the EBCM. The duty cycle of the signal is used to determine how much engine torque the PCM is delivering. Normal values are between 10 and 90 percent duty cycle. The signal should be at low values (around 10 percent) at idle and higher values under driving conditions. The EBCM supplies a pull up voltage of 12 volts that the PCM switches to ground to create the signal.

When certain PCM DTCs are set, the PCM will not be able to perform the torque reduction portion of traction control. A serial data message is sent to the EBCM indicating that traction control is not allowed.
Conditions for Running the DTC

The engine is running.
Conditions for Setting the DTC
C1277

The PCM diagnoses the requested torque signal circuit and sends a serial data message to the EBCM indicating a fault is present.
P1571

One of the following conditions exists:

The PCM detects that requested torque signal is out of the valid range.
The PCM does not receive the requested torque signal.

Action Taken When the DTC Sets

If equipped, the following actions occur:

The EBCM disables the TCS/VSES for the duration of the ignition cycle.
The PCM will store conditions which were present when the DTC set as Fail Records data only.
The Traction Control and Active Handling indicator turns ON.
The DIC displays the following messages:
Service Traction System
Service Active Handling
The ABS remains functional.

Conditions for Clearing the DTC

The condition for the DTC is no longer present (the DTC is not current) and you used the scan tool Clear DTC function.
The condition for the DTC is no longer present (the DTC is not current) and you used the On-Board Diagnostics Clear DTC function.
The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.
The PCM automatically clears the history DTC when a current DTC is not detected in 40 consecutive warm-up cycles.

Diagnostic Aids

The following conditions can cause this concern:

An open in the requested torque circuit
An short to ground or voltage in the requested torque circuit
A wiring problem, terminal corrosion, or poor connection in the requested torque circuit
A communication frequency problem
A communication duty cycle problem
The PCM is not receiving information from the EBCM
Loose or corroded EBCM ground or PCM ground

A DTC P1571 may set along with several other PCM DTCs if the key is held in the CRANK position while the engine is running. The starter lockout function of the PCM is enabled several seconds after the engine is running and prevents the starter from engaging while the engine is running. This will cause a partial loss of power to some components and systems.
Test Description

The numbers below refer to the step numbers on the diagnostic table.

Clear the DTC in order to verify that the fault is present.

Measure the requested torque signal in order to determine if the signal has a valid duty cycle.

Measure the requested torque signal in order to determine if the signal has a valid frequency.

This vehicle is equipped with a PCM which uses an electrically erasable programmable read only memory (EEPROM). When replacing the PCM, the replacement PCM must be programmed.

 

Basically you need to replace it. There are many descriptions about doing it if you do a search on tyhe 1780 common failure.IIRC a 1780 code will cause issues with the TCS too.

 

Replace what?

 

replace my pcm?

 

The reason I couldn't find the code is that I was earching for an 02. Looks like the procedure was dropped for my model.

The CKT 914 which is referred to is a light blue wire that runs from the EBCM to the ESC (electronic suspension control) module. The position of the steering wheel is sensed by the SWPS. A voltage is sent from the ESC to the EBCM and varies depending on stering wheel position.

I have a C1287 and my AH keeps tripping out. One of these days I'll replace the SWPS but its not an easy job.

Here you go George

DTC C1780 Loss of Steering Position Signal

Object Number: 70222 Size: MF
Click here for detailed picture of above image.
Circuit Description

The ESC module receives a steering position PWM signal from the Electronic Brake/Traction Control Module (EBTCM) on CKT 914. The ESC module uses this signal in order to determine the shock absorber control levels and will command a more firm setting if the vehicle is in a turn. The ESC module monitors the steering position circuit and can determine if a valid signal is sent from the EBTCM.
Conditions for Setting the DTC

The ESC module does not detect a valid steering position PWM signal from the EBTCM.
The condition must be detected for 5 seconds in 4 consecutive ignition cycles.

Action Taken When the DTC Sets

Stores a DTC C1780 in the ESC memory.
Ignores the steering position PWM input.
Will continue to control the shock absorbers using the lateral acceleration data sent from the EBTCM on the serial data line.
Sends a message to the IPC to display the SERVICE RIDE CONTROL message.

Conditions for Clearing the DTC

The ESC module detects a valid steering position PWM signal from the EBTCM.
A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
The IPC clearing DTCs feature.
Using a scan tool.

Diagnostic Aids

The following conditions may cause an intermittent malfunction:
An intermittent open or short (to ground or to voltage) on the steering position sensor CKT 914.
Intermittent operation of the EBTCM. Refer to ABS Diagnostic System Check .
If the ESC module does not receive a valid steering position PWM signal from the EBTCM, the RTD system will still function, but will ignore the steering position PWM signal. The RTD system uses lateral acceleration data sent from the EBTCM on the serial data line in order to substitute for a loss of the steering position PWM signal.
The ESC module uses an ignition cycle counter diagnostic approach to set this DTC. This requires the ESC module to detect the malfunction 4 times before setting the DTC. To disable this feature, use a scan tool to clear all DTCs before preforming diagnostic procedures.
An intermittent open or short (to ground or to voltage) on the steering position PWM circuit may cause a random firm/soft ride condition.
If the DTC is a history DTC, the problem may be intermittent. Using a scan tool, monitor the steering position sensor circuit while moving the related wiring and connectors. This can often cause the malfunction to appear.

Test Description

The numbers below refer to the step numbers on the diagnostic table:

This step checks if any ABS/TCS DTCs are present. The EBTCM provides the ESC module with steering position data, therefore all ABS/TCS DTCs that are associated with the steering position sensor must be diagnosed and corrected before attempting to diagnose a DTC C1780.

This step checks if the ESC module is able to receive a steering position PWM signal from the EBTCM.

This step checks for opens or shorts (to ground or to voltage) on the steering position signal CKT 914.

This step checks for an intermittent malfunction and requests a thorough inspection of the related steering position sensor circuit wiring and connectors.

DTC C1780 -- Loss of Steering Position Signal

Step


Action


Value(s)


Yes


No

1


Was the RTD Diagnostic System Check performed?


--


Go to Step 2


Go to RTD Diagnostic System Check

2


Using a scan tool, check for any stored ABS/TCS DTCs.

Are any ABS/TCS DTCs stored?


--


Go to ABS Diagnostic System Check


Go to Step 3

3


Using a scan tool, monitor the steering position PWM input while turning the steering wheel.

Does the PWM reading change when the steering wheel is turned?


--


Go to Step 5


Go to Step 4

4


Check for an open or a short (to voltage or to ground) on CKT 914.

Was a circuit problem found and repaired?


--


Go to Step 8


Go to Step 5

5


Check the steering position signal circuit for an intermittent malfunction. Refer to Diagnostic Aids.

Was an intermittent malfunction found and repaired?


--


Go to Step 8


Go to Step 6

6


Turn OFF the ignition switch.
Connect or install any connectors or components that were disconnected or removed.
Turn ON the ignition switch.
Using a scan tool, select clear DTCs.
After 5 seconds, check if DTC C1780 resets.

Does DTC C1780 reset?


--


Go to Step 7


System OK

7


Replace the ESC module. Refer to Electronic Suspension Control Module Replacement .

Is the repair complete?


--


Go to Step 8


--

8


Turn OFF the ignition switch.
Connect or install any connectors or components that were disconnected or removed.
Turn ON the ignition switch.
Using a scan tool, select clear DTCs.

Is the repair complete?


--


Go to RTD Diagnostic System Check


--

 

where are you getting all this info from?