ABS Failure

PsYcHe · #1 13th March 2011, 03:35 PM

OK Guys,

My ABS has failed

Reporting Right rear sensor implausible signal. I've replaced the sensor, but it's still giving me errors.

I did (probably stupidly) click the 'output tests' button in VCDS, and now it's telling me the controller is faulty. It does respond to VCDS, and it does read the speed from the other 3 wheels.

Any ideas beyond a new ECU (and where is it? might want to have a look inside and see if I can spot a dry joint or test for cable continuity).

Conan_the_Librarian · #2 13th March 2011, 04:02 PM

Swap the sensor onto another wheel Richard and see if the fault goes with it. If not I would suspect wiring before control module.

PsYcHe · #3 13th March 2011, 04:06 PM

You'd think

.. But the sensor only fits one wheel on the D3!

I found the control unit (it's on the back of the ABS block in the engine bay), disconnected the cables from it and will re-check later to night if that's sorted it.

If not, then it'll need to go in to A4Audi as I haven't got time to fart around any more

Just_Ben · #4 14th March 2011, 05:11 PM

Try popping the sensor out and seeing if the reader ring is full of crud or rust. This can totally impare the signal. Or if the mount is coroded/bunged up the sensor sometimes doesn't sit fully home and the resultant larger air gap ruins signal too

PsYcHe · #5 18th March 2011, 06:53 PM

Turns out it's a failed wheel bearing.. That noise I thought was just the tyre worn out was the bearing being gubbed, and it had reached the point where it was so far out of position it was missing the sensor..

Pretty common mis-diagnosis apparently. Another great job by A4Audi

Car is much quieter now, and no longer sounds like a cheap 80's rave when it starts up

Architex_mA8tey · #6 19th March 2011, 01:40 PM

Quote:

Originally Posted by PsYcHe

Car is much quieter now, and no longer sounds like a cheap 80's rave when it starts up

Well only when you play your smash hits CD's

Glad you got it sorted ok
Sounds like you boys up there have a great Garage in A4 Audi

PsYcHe · #7 19th March 2011, 04:35 PM

Should maybe clarify the 'rave' comment..

So many systems in the D3 rely on the ABS that when it takes a turn, they all do. Adaptive Cruise, Headlight Control, Electric Parking Brake, ESP, and obviously the ABS.. Thing would beep and flash for a good minute or so on startup.

Good to know that it's a single failure as I just saw the huge number of pound signs the first time it happened.

A8L Chick · #8 19th March 2011, 08:42 PM

This is really interesting to know... because last time I plugged into VCDS, I had an "ABS Control Module Malfunction" fault show up, yet.... I have NO problems with the function of my ABS, works flawlessly

I have in the meantime just left it as-is.

I have been thinking that I have a wheel bearing gone for a while too-but the local garage said they seemed fine... so I put the noise down to tyres and just had the tracking done.

I am now going to have the wheel bearings done and report back whether this is also the cause for my "ABS Control Module Malfunction" Fault Code, because if it is, making this a well known common problem is going to save some peopl a shed load of cash..... I may be hoping for a little too much here-but it's sure as hell worth a shot.

Can you tell me how much your wheel bearing were-and were they OEM from Audi?

Bex

PsYcHe · #9 19th March 2011, 09:35 PM

AFAIK, proper Audi.. 86+VAT for the bearing, but 3 hours labour becuase of all the fiddly crap, and I think there was some diagnostic time in there.

JulianHicks · #10 14th March 2017, 03:10 PM

Quote:

Originally Posted by PsYcHe

Turns out it's a failed wheel bearing.. That noise I thought was just the tyre worn out was the bearing being gubbed, and it had reached the point where it was so far out of position it was missing the sensor..

Pretty common mis-diagnosis apparently. Another great job by A4Audi

Car is much quieter now, and no longer sounds like a cheap 80's rave when it starts up

Thanks PsYcHe, if you're still tuned in these days.

I had exactly the same issue; same wheel. ABS / ESP/ Parking Brake alarms and VCDS showed me that Right Rear ABS data was 'missing' from the ABS ECU. I put up with for them for two weeks until my trusted service guys could fit me in and suggested that they check the wheel bearing.

Bearing replaced; all DTCs and alarms cleared and gone ...

This is such a great forum ...

Julian