ABS warning still on

[KeithS]

I've had the ABS warning lights come on with the 3 warning beeps for some time now. So far I've tried the following:

- VW garage told me it needed a new ABS control unit. I have fitted a new one, the warning lights did not go away.

- I read the fault codes and got two: rear O/S ABS sensor fault and O/C brake light switch.

- Today fitted a new ABS sensor. Read the codes again; got one with rear O/S sensor intermittent connection (could have been caused by fitting the sensor?). Reset the codes.

- Still got the warning lights on. Took the car for a spin, stopped, read codes again - nothing - but still the warning lights are coming on.

Anyone any ideas? I talked to the people who sent me the replacement ECU, they said send it back and they will test it, which I guess is the next thing to try?

[snapdragon]

Did you replace the brake light switch?

[KeithS]

Did you replace the brake light switch?

Not yet... the one I got turned out to be the wrong sort.

[FLIPKEY]

yep had that problem, brake switch replaced all ok now. one thing to check does the abs light only come on after you have braked ?.

[KeithS]

yep had that problem, brake switch replaced all ok now. one thing to check does the abs light only come on after you have braked ?.

No - it comes on when you turn the ignition on, then stays on.

I'm a bit puzzled as one the original fault codes was an open circuit brake light switch, now why would that cause an ABS error?

[KeithS]

OK had the brake light switch off and tested it and its working fine. So I can only assume that the ABS control unit I replaced is also faulty? Or could there be another reason?

[stuarta]

I had the same thing , also the ESP light would come on , I know you have checked your brake switch , but do both of the brake lights work?

I tested my brake switch and it seemed ok , but as they were only £8 I fitted a new one and replaced my brake light bulbs and they problems went away , that was 20k ago

[kenney]

Hi Was just wondering if the replacement abs control unit has the same coding as your old one? And you can check the signals from the wheel sensors in measured value blocks to make sure these are ok.

[KeithS]

Hi Was just wondering if the replacement abs control unit has the same coding as your old one? And you can check the signals from the wheel sensors in measured value blocks to make sure these are ok.

The ABS replacement unit is the same part number as the original, is that what you mean by coding?

How do you check the signals from the sensors? Is that something you can do with vag-com?

[kenney]

No the part number may be the same but the coding can be differant,you can check the sensor signals in measured value blocks for the break system iam sorry iam not familiar with vag-com so i dont know which channel you need, perhaps Crasher gan help you there

[Crasher]

Can you describe the problem as it is now and the fault codes you are getting now? Can you post the VAG-COM screen for the ABS?

[KeithS]

No the part number may be the same but the coding can be differant,you can check the sensor signals in measured value blocks for the break system iam sorry iam not familiar with vag-com so i dont know which channel you need, perhaps Crasher gan help you there

I'm not sure if I understand... you mean you need to set some code in the control unit? I was under the impression you could just replace the existing control unit with one of the same type.

Appreciate any help as the MOT is due at the end of January and its not going to pass with the warning light on!

[KeithS]

Can you describe the problem as it is now and the fault codes you are getting now? Can you post the VAG-COM screen for the ABS?

Hi Crasher,

I don't have vag-com alas, I have a VAG405 from Autel which is a handheld fault code reader.

What happened went like this:

- started getting the ABS light / red warning light coming on, initially intermittently, typically after braking.

- took it to my local garage who could not seem to find any errors

- the warning lights then came on permanently every time the ignition was switched on

- took it to the VW garage who wanted £1043 to change the abs control module

- I replaced the abs control unit with one from ecu testing. Warning lights did not go away.

- checked it on the VAG405, it reported a rear o/s abs sensor problem and open circuit brake light switch.

- replaced the rear o/s sensor and have checked the brake light switch which is working OK (its the 2 pin type).

- cleared the error codes, but the warning lights still won't go away.

thanks for any help!

[Crasher]

So the light is on but there are no codes?

[KeithS]

So the light is on but there are no codes?

Yes, that's correct - tried taking it out for a run, turning off & on the ignition and re-checking but no codes reported now. The lights come on and stay on though.

As a measure of last resort I could try sending the ABS control unit back and seeing if the ecu testing people have any idea?

[Crasher]

That is odd, the light should not be on if there are no codes. Try sending the unit to http://www.bba-reman.com , they are the best people for this work.

[KeithS]

If there's anyone who has vag-com in 30 miles or so of the Reading area that could try reading the fault codes for me please PM me - I am not totally convinced the handheld code reader I've got is OK. Thanks.

[kenney]

Hi again Although the control light is on,does the abs function when you brake ?

[KeithS]

Hi again Although the control light is on,does the abs function when you brake ?

I don't think so. According to the manual, if the ABS light is on then ABS is disabled.

Unfortunately despite having perfectly workable brakes I am told that this is grounds for a MOT failure...

[kenney]

No faults,new control unit,i was thinking,before you remove and send the unit,see if the abs functions, the way it should, there (might) just be something with the control light itself without it affecting the abs function

[KeithS]

OK another ABS control unit fixed the problem. Seems like the one that ECU testing supplied was faulty.

[ROBBIE MALLOWS]

I have just had my audi a3 2006 1.9 tdi in to audi to have the esp warning light fault diagnosed at the cost of £120.00 and have been informed the abs control unit needs replacing at the cost of £1,211.37. I have read about numerous complaints of the same unit on golfs, seats, and skodas. This must be a substandard unit and should be replaced as a recall. Audi refuse to help or admit the fault is with them. Any suggestions?

[Crasher]

If VAG Germany replaced all the faulty Mk60 ABS pumps on the Golf 5/A3 etc platform that had failed due to a G201 fault code under warranty, even with the cooperation of the parts manufacturer both VAG and Siemens would go bust, there are literally tens of millions of them out there.

[KeithS]

If the problem appeared in cars less than 3 years old then VW/Audi may have more incentive in doing a recall, however it seems to only occur on older cars. The problem is the Bosch ABS controller which has a chip in it with bond wires connecting it. Over time the wires come loose and so the unit fails.

VW/Audi must know about this problem, its been around many years now - mine was on a 1998 passat.

[Crasher]

It is not Bosch, it is Siemens, the Bosch controller fault was different and must easier to fix.

[KeithS]

There's another problem then? Jeez they don't seem to learn quality control lessons...

[Crasher]

It is not just VAG that are suffering from these issues and they don’t control the quality, it is the manufacturer of the part. The same problem is afflicting Ford, Mazda, Vauxhall/Opel, BMW, Mercedes and some others that use both designs of pump made by Bosch and Siemens.