I have been having problems with my PDAS and ABS lights recently, no having them come on as soon as the car is started. I have tested as much as I can with a multi meter and have found that the accelerometers and the ABS solenoids don have any power. All cables have continuity to the ABS ECU so something is at fault and telling the ECU not to put power on to them.

I am wondering now if it could be a fault accumulator or ABS pump? the brake booster pump does come on every 5-10 minutes so i take it I have a small leak somewhere. If it isnt holding pressure could this cause these symptoms?

Cheers
Darryn

 

The valves and accelerometers have different operating voltages sourced by pump mounted relays and from within the C4 ABS/PDAS controller, you seem to have a lot involved. Not pushing my solution, but these kinds of problems are why I developed the ABS Test Sets for the C2 and C4. You energize and exercise everything from the ABS controller connector. You C4 guys do have some extra gyrations involving the pressure accumulator and switches to consider as well. Please PM me if you would like more info on the C4 ABS Test Set.

Michael, (cajonfan)

 

Hi Darryn

I think I have a very similar fault

Did you get it resolved?

Thanks in advance
Phil

 

Yes, always seems simple when you eventually find it. I found my problem to be a speed sensor not plugged in properly. I only found it by doing a continuity test between the ecu outputs and the sensors. I have a spare brand new un used sensor if you do need it. I bought it thinking it needed replacing but obviously didn't. Hope this helps mate.

 

Thanks Darryl - and sorry for me very slow reply
I'll investigate accordingly
Phil