radjaco

I have 1997 A8, 3.7 (European model). Recently an ABS and TC lights came on. Diagnosed with VAGCOM says the RIGHT ABS sensor malfunctioning. The lights used to come only when making sharp turns. After restarting they would not come on until I make the sharp turn. Logically could be 2 reasons: either wiring of the sensor or the sensor itself.
I checked the wiring and it looked fine, no damages or tears. I removed both sensors and cleaned them. It did not change anything - the lights came on and during sharp turns.
However, one interesting thing happened: when the car was on a rack and I turned the steering wheel to either direction the lights would not come on - only during driving. I guessed it might have been a bearing as the sensor reads impulses from it. but the bearing was fine like new,
I kept on testing the car driving around and only sharp turns to the right would trigger the lights to come on. Just mild turn to the right would not turn them on.
I begin to think that there may be the wheel alignment involved, So, here is my question: can the front wheel alignment pose a problem for the ABS sensor to function correctly? This is just a guess as only right wheel sensor malfunctions and only in sharp turns to the right. I would appreciate your feedback and suggestions.

jfrahm

IMO no, it's just a bad wire to the ABS sensor that fails under stress. Common issue.
On the FL I use A4 sensors spliced to the A8 harness as they are way cheaper, yours are different but there might be an inexpensive alternative also if you are concerned about cost.

radjaco

jfrahm, thanks a lot for your reply. Could you please tell me more about the A4 sensor and harness of A8? Does A4 sensor fit my model? Actually I noticed that practically only middle part of the wire can be damaged as the front and rear are quite static. I found this thread audipages A8 ABS Troubleshooting

Do you think that this is the problem? Please give me more details about the A4 sensor with A8 harness, how to fix it.
Thanks

radjaco

Or maybe this is the way to fix it.?

However, your suggestion sounds more reliable.
Thanks for more details.

radjaco

Please do not take amiss my second request regarding the big exclamation light on the dash screen which I cannot get rid off despite all my efforts to fix problems connected with brakes. So, a) the pads are practically new, b) I have cut the sensors on brake pads and shortened the dash wires to eliminate another yellow brake light which now does not show. c) ABS works and I feel it. d) Brake fluid reservoir is full and the filter in it does not seem to be sticking as it floats when I push it. e) connector to the fluid level sensor under the reservoir is tight and cleaned (I have not taken the sensor out yet although ordered the new one), f) Front rotors are new and recently replaced, g)Mine is FWD and has no rear sensors, g) Diagnostics does not through any codes on brakes or brake system.
So, how to get rid of this big red light beginning with 3 beeps once I start the car and stays on?

Thanks in advance

jfrahm

Yes you could try rewiring the ABS sensor as per your pic. If not look up replacing the ABS sensor with the correct A8 part which will have the wire and connector.If that is really expensive look at other Audis from a similar year to see if the sensor appears to be compatible and go from there. In my case (2001-2003) the A8/S8 sensor was $180 and the A4 sensor was $15, the wiring was different but easy to splice.