ABS warning still on

**KeithS** · 22-12-2007,04:59 PM

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** · 22-12-2007,05:59 PM

Did you replace the brake light switch?

**KeithS** · 22-12-2007,06:09 PM

Originally Posted by snapdragon

Did you replace the brake light switch?

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

**FLIPKEY** · 23-12-2007,12:21 PM

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** · 23-12-2007,01:33 PM

Originally Posted by 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 ?.

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** · 24-12-2007,12:18 PM

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** · 24-12-2007,12:53 PM

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** · 24-12-2007,01:16 PM

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** · 24-12-2007,02:59 PM

Originally Posted by 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.

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** · 24-12-2007,04:07 PM

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