Fighting with ABS and traction control light

[onceover]

For the past year or so I've had an intermittent problem where the ABS and traction control lights would come on. This would disable ABS and traction control. Turning the car off and turning it back on would usually fix the problem.

It got to the point where that would no longer fix it, but cycling the ignition while the car was rolling would. I would have to do this every few days.

Now its gotten to the point where the lights are on when I start the car, and cycling the ignition with the car rolling will sometimes solve it for 1-2 minutes.

I've scanned with VCDS and get this code:
00285 - ABS Wheel Speed Sensor; Front Right (G45)
30-00 - Open or Short to Plus

I've tried 3 different wheel speed sensors on the passenger side of the vehicle and none of them have fixed the issue. I assume front right is the passenger (US) side?

Anyone have an idea as to what the problem could be?

[xhackerekx]

u need replace abs unit simple.

[onceover]

How did you deduce that if I may ask? I have a spare unit so it's not a big deal, but it would be nice to have confirmation before I tear it apart

[Fast4esT]

Have you checked the wiring from the sensor for a broken wire?

[onceover]

It goes right into the body of the car, impossible to check really

[agentsmith988]

Have you tried cleaning any of the harness contacts with electrical parts cleaner? I thought I had a failed abs module or sensor once and I ended up just having to spray down some contacts on a harness.

[onceover]

Contacts are pristine since theres rubber grommet that the wires go into the body where the connection is.

[csosnowski]

Bad EBCM, I have seen this before on several other vehicles. The wire trace from the connector to the board inside the module degrades and goes open circuit.

k0mpressed has a video floating around of him repairing one for a B5, but the process is similar.

You can get a new one from a wrecking yard and use Ross-tech's website to calculate the coding.

[onceover]

Awesome news. I have a spare kicking around in the garage from a S4 I parted out.

Now the question is, can I swap the electronics without having to pull the module out and re-bleed the system?

[itsmatt33]

same EXACT issue, its abs

[DiertyEuroSpec]

Awesome news. I have a spare kicking around in the garage from a S4 I parted out.

Now the question is, can I swap the electronics without having to pull the module out and re-bleed the system?

Yes you can just have to take out the 6 same screws that attach the electronic module and pistons to the body. No need to get into the fluid section of the unit. I also had this issue and seems very common on lower years mine is an 03, and they made a revision to the unit. Also you will probably have to re-code via VCDS.

[onceover]

Exact same code with the S4 module...

Anyone have a pinout for the ABS connector? I'd like to check all the wires leading to the passenger front sensor for continuity

[DiertyEuroSpec]

Did you recode the S4 module to your vehicle?

[ECS Tuning-Audi]

Does your speedo stop working when your ABS and ESP lights come on?

Jason

[onceover]

Did you recode the S4 module to your vehicle?

Attempted to. Can't get the coding to stick. The 00285 code comes up regardless though, and pops back immediately after clearing.

Does your speedo stop working when your ABS and ESP lights come on?

Jason

Speedo continues to work

[ECS Tuning-Audi]

Speedo continues to work

Hmm. Mine might be just a sensor then. When both my ABS and ESP lights come on my speedo drops to zero. And wont work again until I restart or key off and on while rolling.

::fingers crossed::

Jason

[onceover]

I've tried 3 different sensors without success. Front right is the passenger sensor, correct?

[ECS Tuning-Audi]

I'll have to double check. I know I got a sensor code but which one it was skips my mind at the moment.

Jason

[onceover]

Tried unplugging the drivers side sensor and got an open circuit code for the left front. This leads me to believe that both ABS modules are in fact good. Tried swapping two different sensors with the S4 module on the front right wheel and didn't make a difference.

Swapped the original module back in an recoded it without any trouble. Now the ABS and traction control light are on permanently. Cycling the key while rolling doesn't seem to fix it. Speedo still works.

[treysgreen]

I fought with this for a long time off and on. Tested each sensor, ABS module etc. Finally, I cleared the magnetic metal shaving from the brakedust from around the sensors and voila. Never came back. I have also heard that the slightest scratch on the ABS sensor ring can cause this. So check that. It looks like the picture below. You can take a flashlight and look in through the hole with the sensor out, or take the front wheel hub assembly off and check it out in whole.

[DiertyEuroSpec]

Attempted to. Can't get the coding to stick. The 00285 code comes up regardless though, and pops back immediately after clearing.



Speedo continues to work

This is your issue. When I replaced my ABS module the ABS and ESP lights did not go away until the module was re-coded for my car setup. Sorry buy you have to try harder and read about re-coding ABS. VCDS on Youtube has a video about it.

I know it didn't happen the first time I tried it either, you have to put some effort into it.

Edit: If you are coding the unit correctly than it chould in fact be the fact that the ABS ring is damaged or has shavings/brake dust/dirty. Let us know what becomes of this.

[pwest15]

Hmm. Mine might be just a sensor then. When both my ABS and ESP lights come on my speedo drops to zero. And wont work again until I restart or key off and on while rolling.

::fingers crossed::

Jason

This is the exact issue I have right now, or have had for months. I'm sending my module to get rebuilt and hopefully, that'll solve my issue

I fought with this for a long time off and on. Tested each sensor, ABS module etc. Finally, I cleared the magnetic metal shaving from the brakedust from around the sensors and voila. Never came back. I have also heard that the slightest scratch on the ABS sensor ring can cause this. So check that. It looks like the picture below. You can take a flashlight and look in through the hole with the sensor out, or take the front wheel hub assembly off and check it out in whole.

See when I cleaned all four of mine, the issue still came back which leads me to believe that there's a large combination of things that can go wrong to cause the same issue.

OP, I would clean the axle ring that Trey mentioned and see if that helps. Then perhaps invest in a new wheel speed sensor and finally, if none of those options work, you can find someone to rebuild your abs module or mail it to a bosch module rebuilder

EDIT: I take that back. In order to get the coding to"stick" you have to complete the coding sequence and not close vcds. You have to immediately recalibrate the yaw sensor I believe or G85 steering sensor iirc. It's been around a year since I recoded one of these but I remember running into the same issue as you. That one final step is what makes the car remember the recoded module for some reason as unintuitive as it sounds

[onceover]

Let me try to clear some things up.

-The code reads "open circuit" indicating that there is something physically wrong with the wiring
-I have tried 3 different sensors with 2 different modules - all read the same open circuit code
-I have disconnected the front left (other side) sensor with the S4 module that was not coded properly and it showed up as an open circuit in the fault codes - Dissapeared when reconnected
-The fault code remains the same whether the sensor is in the vicinity of the ABS ring or not
-The fault code remains the same when the sensor is completely disconnected
-I had no problem re-coding the original ABS module so I know what I'm doing - for whatever reason the S4 module will not cooperate
-The fault code will re-appear immediately after clearing with BOTH modules regardless of whether they are recoded or not

All of these things lead me to believe that it is a physical wiring issue within the wires leading from the sensor connector to the ABS module. I am going to try the S4 module in a friends car and see if it reads the same fault code - if the same code shows up I know that both modules are bad.

[onceover]

Did some diagnosis today. Still haven't solved the problem though.

-Pulled the axle and checked the ring - looked clean, cleaned it anyways, some minor scratches but doesn't look bad.
-There is continuity between the two sensor connector wires and the ABS module connector - good
-There is NO continuity between the sensor connector and ground or the positive battery terminal - good
-If I unplug the drivers side front sensor the passenger side code disappears - then when I plug the drivers side sensor back in the passenger side code re-appears. Wheel speed will not register on either front wheel when front left is unplugged.
-When all sensors are plugged in, wheel speed registers on all but front right in VCDS

[onceover]

Is theres any chance it could be a brake light switch or clock-spring/wheel angle sensor even if there isn't a code for it? I've got a B7 MFSW installed.

The steering angle in VCDS works perfectly fine. Are there any other measuring blocks I could check to see if there's any issues?

[onceover]

Got the module repaired and still have the same fault code.

I've literally tried to fix everything that could be causing this. Time to go light it on fire.

[diagnosticator]

Awesome news. I have a spare kicking around in the garage from a S4 I parted out.

Now the question is, can I swap the electronics without having to pull the module out and re-bleed the system?

Yes, you can swap the controller part without removing the hydraulics part. There is not much room for the torx tool that you need to use to remove the screws holding the controller to the hydraulics, but it will be relatively easy anyway. Make sure everything is clean before taking the ABS apart, including the harness connector. The new (used) controller will need to be recoded for engine, trans, and brake size after installation. When the login code is determined during re-coding, remember to use the values associated with the original vehicle installation, not the new installation.

[onceover]

John,

Thanks for the tips, but I've already done this. 4 times now...

A4 module after repair seems to work SLIGHTLY more often. When I start the car it will work for maybe 5 minutes, then throw the code again.

What the hell else is there to check? Could there be a ground somewhere that needs to be cleaned/tightened? I'm at my wits end on this and think I'll just sell the car.

[marklar182]

Going through the same issue, just sent my module out for repair. Fingers Crossed.

[customa4]

After all of the diagnosis my guess is something to do with wiring between the two units. It looks like you might have covered that already but it's the only thing that I could think of with all the testing you've done.

[Let it snow]

Perhaps the female electrical connections at the sensor or module are no longer making good contact.

[daverdfw]

I am fighting something very similar http://www.audizine.com/forum/showth...t-switch-issue

Not sure where else to look. I hope its not the ABS module.

[marklar182]

Going through the same issue, just sent my module out for repair. Fingers Crossed.

Module repaired, seemed to fix the issue. No more lights or codes.

[onceover]

Plot twist.

After driving the car for a few days with the repaired module I'm getting the following behaviour:
- Start car and lights are off - ABS functions perfectly
- Drive for approx 5 minutes and the lights turn on - no more ABS or traction control, speedo still works
- Cycling the key while the car is rolling will no longer make the lights go out for a while

Seems to me that this is now heat related somehow? Once something warms up contact is lost potentially. Could this be possible?
Where are the yaw sensors located? I feel like I remember there being a module under the center console, is there any chance this could be the culprit?

[daverdfw]

Module repaired, seemed to fix the issue. No more lights or codes.

Who did you use? I just sent mine off to cheap ABS yesterday.

[marklar182]

Who did you use? I just sent mine off to cheap ABS yesterday.

Same.

[onceover]

Any chance it could be a faulty cluster or a wire leading to the cluster? Looking at wiring diagrams it seems like the ABS module and cluster are connected somehow.

[diagnosticator]

I noted when you disconnect one side wheel speed sensor, the other side shows as disconnected. Can you swap the sensor connections in the ABS connector?

Is the PN of the S4 ABS controller the same as the original controller?

The ABS controller is connected to the instrument cluster via the Drive train CAN. The vehicle speed is sent to the cluster via CAN. You can view the status of the three CAN busses in VCDS, and the installed controllers on each buss.

If the PNs of the original and replacment S4 ABS controllers are the same, using the same procedure for recoding the original controller should work on the S4 cluster. The only difference is the login code determined for the two controllers, since the S4 has a different baseline equipment list used to determine the login.

[onceover]

I've tried a few times to get the S4 module to recode but couldn't get it to take my login code. Even when the module is incorrectly coded it throws the same DTC.

Tried de-pinning the wires for the front left and right speed sensors and swapping them and the same code appears. So it's not the sensor, ABS ring, or wiring.

Tried a spare clockspring - didn't help.

Tried a new brake light switch - didn't help

Tried a spare yaw sensor - didn't help.

Next I'll try replacing the rear wheel speed sensors. After that pretty much everything to do with the ABS has been replaced.

[diagnosticator]

I've tried a few times to get the S4 module to recode but couldn't get it to take my login code. Even when the module is incorrectly coded it throws the same DTC.

Tried de-pinning the wires for the front left and right speed sensors and swapping them and the same code appears. So it's not the sensor, ABS ring, or wiring.

Tried a spare clockspring - didn't help.

Tried a new brake light switch - didn't help

Tried a spare yaw sensor - didn't help.

Next I'll try replacing the rear wheel speed sensors. After that pretty much everything to do with the ABS has been replaced.

The login I determine for the S4 ABS controller is: 09295 If the donor S4 was manual transmission, and 09297 if tiptronic. If your A4 has FNR G60 345mm S4 front brakes, The coding of the controller is 04575. What is the current coding of the S4 ABS controller installed? If it is already 04575 then the coding does not need to be changed, but the basic settings would still need to be reset.

If the S4 ABS won't recode using any login or coding value, then it is most likely defective. Also likely defective if the same DTC can't be cleared.

What is the PN of the installed S4 ABS controller?