Hello, I have a 2002 A4 and a host of error codes are on, first i had a buddy check them with his snap on OBD2 scanner and we came up with our problem (or at least narrowed it down) to this module (i can remember if he said yaw rate sensor or something like that) anyway the normal operating voltages are between .25 and 6 or something like that and we read 1.4 but when the car is just sitting it is supposed to be around 3 (i think, again just going off memory) so we deduced it had to be plugged in but just not mounted correctly so this afternoon i took off my center console and sure enough it was just hanging out in there not fastened to anything. SO my question is WHERE is this supposed to go and HOW is it supposed to be mounted/calibrated? Here is a picture so yall know what i'm talking about.



Thanks in advance

 

also i have access to ALLDATA i just don't know the error code/what the name of this module is, so if someone can tell me what it is than i can search it in all data and come up with it. THANKS!

 

From the 2002 SM, Yaw rate sensor goes here:



Your pic looks like something else though.

 

thanks, yeah i looked at that right after i posted so i don't think it's the yaw rate sensor... but i don't know What it is... all i know is that it's loose and it needs to be fastened in a way that is correct (orientation wise) for the codes to go away...

 

lateral accelerometer maybe? and it is supposed to be mounted under the passenger seat? which my new quesiton is since i have racing seats in my car does this mount to THE SEAT or to the floorboard under the seat?

 

Alright i got on alldata turns out it IS the lateral accelerometer. It looks like it goes on the floor or something like that but i can't find exactly where it fastens... any help would be appreciated. (maybe just right of the center consol on the floor just in front of the seat???)

 

Here are some pictures so you know what i'm talking about, first one is so that you can see where in the car i'm working (ignore the rusty e-brake mount) and second so you can see the outline of where i think it SHOULD go (there is also a bump in the carpet) it's got a little line in the shape of it but there are not holes to screw into and all data shows there should be some studs or something to slip it on and put some nuts to fasten it down with. IDK i'm so lost and just want these error codes to go away.



Here is what alldata provides for a picture....

 

It looks like somebody took the screws out or ground them down. However, if you have codes related to the yaw or lateral g sensors you need to resolve them first. Just mounting the sensor where it is supposed to be is not going to resolve an internal problem in the sensor or the EBCM.

What are the codes? They can be displayed on the DIC so you do not need the scanner. You can use a DMM to make the measurements your buddy was making with the scanner.

Bill

 

THANKS BILL the only codes i pulled off the DIC where a C1287 and B2809 which is unrelated
for the C1287 this is what i pulled off ALLDATA and for the voltage reading with the DMM do i just stick the probes in the pins of the connector? P.S. no one has a picture of THEIRS mounted do they???

Test 14 - 20

Circuit Description
The Vehicle Stability Enhancement System (VSES) is activated by the EBCM calculating the desired yaw rate and comparing it to the actual yaw rate input. The desired yaw rate is calculated from measured steering wheel position, vehicle speed, and lateral acceleration. The difference between the desired yaw rate and 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 will attempt to correct the vehicle's yaw motion by applying differential braking to the left or right front 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 side slip rate error is a function of the lateral acceleration minus the product of the yaw rate and vehicle speed. The yaw rate error and side slip rate error are combined to produce the total delta velocity error. When the delta velocity error becomes too large and the VSES system activates, the driver's steering inputs combined with the differential braking will attempt to bring the delta velocity error toward zero.
The VSES activations generally occur during aggressive driving, in the turns or bumpy roads without much use of the accelerator pedal. When braking during VSES activation, the brake pedal will feel different than the ABS pedal pulsation. The brake pedal pulsates at a higher frequency during VSES activation.
The usable output voltage range for the lateral accelerometer and yaw rate sensors is 0.25 - 4.75 volts. The scan tool will report zero lateral acceleration or yaw rate as 2.5 volts with no sensor bias present. The sensor bias compensates for sensor mounting alignment errors, electronic signal errors, temperature changes, and manufacturing differences.
The steering wheel position sensor supplies 2 analog inputs, Phase A and Phase B, to the EBCM. The 2 input signals are approximately 90 degrees out of phase. By interpreting the relationship between the 2 inputs, the EBCM can determine the position of the steering wheel and the direction of steering wheel rotation.
Steer angle centering is the process by which the EBCM calibrates the steering sensor output so that the output reads zero when the steering wheel is centered. Using the yaw rate input, lateral accelerometer input, and wheel speed sensor inputs, the initial steering center position is calculated after driving greater than 10 km/h (6 mph) for more than 10 seconds in a straight line on a level surface.

Conditions for Running the DTC
The ignition is ON.

Conditions for Setting the DTC
C1287
One of the following conditions exists:


The steering wheel position sensor is synchronized and the steer rate (speed that the steering wheel appears to be turning) is greater than 1100 degrees/second.
The steer rate is less than 80 degrees/second and the difference in the phase angle between Phase A and Phase B is greater than 20 degrees.
The 2 steering sensor signals (Phase A and Phase B) do not agree for 1 second. Under this condition, this DTC will set along with DTC C1281.
C1288
One of the following conditions exists:


Both Phase A and Phase B are greater than 4.9 volts for 1.6 seconds.
Both Phase A and Phase B are less than 0.2 volts for 1.6 seconds.
The difference in the changes in Phase A and Phase B is greater than 35.2 degrees for 9.76 milliseconds.
Action Taken When the DTC Sets


The EBCM disables the VSES for the duration of the ignition cycle.
The Traction Control and Active Handling indicator turns ON.
The DIC displays the Service Active Handling message.
The ABS/TCS 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.
Diagnostic Aids


The scan tool may display 2 additional characters after the DTC. Take note of the 2 character code and any other DTCs that are set. The 2 character code is an engineering aid used in order to determine the specific criteria which caused the DTC to set.
During diagnosis, park the vehicle on a level surface.
Check the vehicle for proper alignment. The car should not pull in either direction while driving straight on a level surface.
Find out from the driver under what conditions the DTC was set (when the DIC displayed the Service Active Handling message). This information will help to duplicate the failure.
The Snapshot function on the scan tool can help find an intermittent DTC.
Test Description
The numbers below refer to the step numbers on the diagnostic table.


Perform the Steering Position Sensor Test in order to verify if the Steering Wheel Position Sensor (SWPS) is operating properly.
Tests for the proper operation of the steering wheel position signal A circuit in the low voltage range.
Tests for the proper operation of the steering wheel position signal B circuit in the low voltage range.
Tests for the proper operation of the steering wheel position signal A circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
Tests for the proper operation of the steering wheel position signal B circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
Tests for a short to voltage in the 5 volt reference circuit.
Tests for a high resistance or an open in the low reference circuit.

 

Surely someone on here that has had the carpet out has seen this before, and can tell you how it is fastened to the floor. That is the correct place for it, and from your picture, it looks like it was glued to the floor.

 

I just looked it up in my 2003 GM Service Manual. The pic in the book shows that the Lateral Accelerometer goes exactly where those two black screws are seen in the picture posted above,that are mounting the E-Brake. The manual also shows two studs coming out of that location, not screws. It also says to remove the lateral accelerometer you need to "remove the two nuts securing the accelerometer". Could someone have disassembled the E-brake in the past and put it together wrong?

 

My '02 service manual shows it mounted to the floor, just behind the front inboard pasenger seat mounting stud. I just went to my car and checked, that is where it's mounted.

 

Thanks for the replies. Byron hunter you said it's behind the front left pass. seat mounting stud??? interesting, would you mind taking a picture of what you're seeing (if you don't have the carpet torn out just open it in paint and draw and arrow or something) that would be GREATLY appreciated, you can see the pass. mounting stud in the picture and this is exactly where you described i just don't have anything to mount it to... so i may just get some self tapping screws and double check under the car to make sure i don't hit something and just screw it in. the only thing then is there are two (2) possible ways to mount it so i have a 50/50 chance on getting it right it guess.

 

that's what i thought at first and i kinda held it there and it looked right untill i backed those scres out and the ouside diameter of the screws was WAY larger than the inside diameter of the holes on the L.A. bracket...

 

Sorry I don't have the carpet out. Your picture shows an imprint of it on the floor. It mounts with the wiring connector pointed pointed out. I'm going to go put my car on the lift and look at the underside of the floor to see if there is any sign of mounting studs. Again, your pix makes it look like it was glued to the floor.

 

Alright, R6, I had to pull the seat. No signs of studs underside. Didn't pull carpet. Ran my hand under carpet and felt of it. It's mounted with two studs, centered aprox 4.5" behind prev mentioned seat stud. Wiring connector pointed to righthand side of car, then the wire is folded right back across the top of it. There is a big hump in the carpet that will show you where it goes. HTH

 

THANK YOU, i can not express how much i appreciate your help! now when i'm done with school for the day i can mount this up clear the codes and check the voltages... hopefully this takes care of some of my problems...

 

Welcome!!!

 

Does it have a part number on it that you can look up?