ABS and PSM warning lights on

[Scouser]

Washed the car today and took it for a ride. About an hour into the drive, the ABS and PSM warning ights came on. Pulled over, turned car off, removed key. Then started her back up again. All fine. 5 minutes later same thing. Now the lights are on all the time. Anybody got any ideas on this?

One thing, I have a feeling my brake discs need to be replaced as they are getting thin, deep groove around the edge. The pads are fine though. Lots of meet on them yet. If the discs get too thin could this cause these warning lights to come on?

Or maybe could I have caused an electrical fault when I washed the car. I did give the wheels a real good going over with the power hose.

Also, while on the subject, is it advisable to change the pads with the disks even if the pads are good?

Cheers

[Loren]

The ABS and PSM share the same speed sensors on each wheel. A PST2 would tell you which sensor is likely triggering the fault - but you might just check and or clean the electrical connection on each wheel sensor. Be sure and do any plugging and unplugging with the ignition off.

IMHO - if you are getting new rotors then change the pads. The problem is your old pads have worn to fit the old grooved rotors so they would not be making full contact on a new rotor - as least not until they had worn enough.

[Scouser]

Thanks Loren.

As it happens, I started up the car this morning and took it for a ride. The lights don't come on now. My guess is a little water got in the ABS eletricals and it's now dried out.

I think I will take the wheels off and clean up the connections. But do you have a diagram of where exactly these ABS sensors and their connections are?

Many thanks in advance,

[Loren]

Front speed sensor (item 3)

Rear speed sensor (item 5)

[Scouser]

Many thanks again Loren.

[SLang]

Scouser - just wondering what suspension you have. My 996 with the H&R coilovers has a tendency to lift a front wheel off the ground going in/out of driveways. The other day I stopped 1/2 way out of a driveway, with a front wheel off the ground. After traffic cleared, I went, and the initial lack of rotation on the front right, combined with the instant rotation of the other three wheels was enough to fire off my PSM and ABS lights as well. They went off a short time later. I guess the system fired them off because it thought the sensor on that one wheel had failed.

[Scouser]

SLang, you may have a good point there.

The first time the ABS/PSM lights went on was while I was driving down a hill that was absolutely full of pot-holes. I hit one and the lights came on. Then I pulled over for petrol and turned the car off. When I restarted it the lights were off but then they came back on very shortly after I left the petrol station. Now that I think of it, the petrol station did have an off driveway onto the main highway and I had to trun immediate sharp right to join traffic (we drive on the left remember). I didn't link them together until your post. So I think you may have something there.

I have M030 kit to Euro spec. I am not sure the difference to the H&R coilovers but my car sits fairly low and it is extremely rigid.

Edited March 7, 2005 by Scouser

[SLang]

The H&R's severely limit the amount of downward travel in the suspension. The M030's may also do this via more limited shock travel than the standard suspension. I'm guessing that this is more likely to be what happened to you rather than water getting into the sealed system and firing off the lights.

The ABS/PSM systems don't appear to appreciate getting different wheel spin rates for even very short periods of time.

[Scouser]

Alas the warning lights came on again just driving down a good highway at about 60mph. So I am leaning towards a faulty connection. Time to get the wheels off.

[SLang]

Scouser, any update on this?