ABS & PSM Lights on with 02' 996 C4S

[petes]

Hi

I was driving into work this morning and the PSM and then about 1 sec later the ABS light came on. They both went off when I turned off the ignition and then came on again a little later. I read in other posts that this might be a brake light switch or a MAF, or perhaps somehing else. I'll check the brake lights as suggested later but wanted to ask ...

a ) Do I need to do the brake light check when the PSM/ABS lights are on, or at any time - i.e. do I need to wait for the lights to come on again before I can know if checking the lights is telling me anything

b ) If it is the brake light problem, is this only the lights coming on, or is PSM/ABS actually off

c ) If they do this "lights coming on, but resetting every time", is it actually a PSM problem - i.e. will PSM actually not be working

d ) Does this brake light problem as occur on a 02 C4S?

Thanks

Peter

Edited October 7, 2008 by petes

[Loren]

a. It does not matter - you are checking the brake light switch.

b. They are likely off if their lights are on.

c. Not in my experience.

d. It can occur on any 9x6 series car.

[milleruspp]

a. It does not matter - you are checking the brake light switch.

b. They are likely off if their lights are on.

c. Not in my experience.

d. It can occur on any 9x6 series car.

Loren -

I read this post and I am having a similar problem. I asked the dealer to look into it and was told that sometimes dust gets into the ABS sensors and to try and "hard brake" to see if it could be dislodged. They said that if that didn't work, I would need a $3,500. computer replacement. Needless to say, the "hard braking" didn't do a thing. Could my problem be as bad as the dealer indicated or are they just churning for dollars?

[Loren]

a. It does not matter - you are checking the brake light switch.

b. They are likely off if their lights are on.

c. Not in my experience.

d. It can occur on any 9x6 series car.

Loren -

I read this post and I am having a similar problem. I asked the dealer to look into it and was told that sometimes dust gets into the ABS sensors and to try and "hard brake" to see if it could be dislodged. They said that if that didn't work, I would need a $3,500. computer replacement. Needless to say, the "hard braking" didn't do a thing. Could my problem be as bad as the dealer indicated or are they just churning for dollars?

The dust line was just that a line. The ABS sensors are magnetic sensors.

Find someone with the Durametric software, a PST2 or PIWIS tester and have them check for fault codes and run the diagnostic test on the ABS/PSM system.

It would be unusual for it to be the controller - 9 time out of 10 it is a bad brake switch or even a bad MAF.

[dubmekanik]

a. It does not matter - you are checking the brake light switch.

b. They are likely off if their lights are on.

c. Not in my experience.

d. It can occur on any 9x6 series car.

Loren -

I read this post and I am having a similar problem. I asked the dealer to look into it and was told that sometimes dust gets into the ABS sensors and to try and "hard brake" to see if it could be dislodged. They said that if that didn't work, I would need a $3,500. computer replacement. Needless to say, the "hard braking" didn't do a thing. Could my problem be as bad as the dealer indicated or are they just churning for dollars?

The dust line was just that a line. The ABS sensors are magnetic sensors.

Find someone with the Durametric software, a PST2 or PIWIS tester and have them check for fault codes and run the diagnostic test on the ABS/PSM system.

It would be unusual for it to be the controller - 9 time out of 10 it is a bad brake switch or even a bad MAF.

Is it possible for the ABS/PSM module to pick up on a faulty maf, and the DME show no faults?

[Loren]

a. It does not matter - you are checking the brake light switch.

b. They are likely off if their lights are on.

c. Not in my experience.

d. It can occur on any 9x6 series car.

Loren -

I read this post and I am having a similar problem. I asked the dealer to look into it and was told that sometimes dust gets into the ABS sensors and to try and "hard brake" to see if it could be dislodged. They said that if that didn't work, I would need a $3,500. computer replacement. Needless to say, the "hard braking" didn't do a thing. Could my problem be as bad as the dealer indicated or are they just churning for dollars?

The dust line was just that a line. The ABS sensors are magnetic sensors.

Find someone with the Durametric software, a PST2 or PIWIS tester and have them check for fault codes and run the diagnostic test on the ABS/PSM system.

It would be unusual for it to be the controller - 9 time out of 10 it is a bad brake switch or even a bad MAF.

Is it possible for the ABS/PSM module to pick up on a faulty maf, and the DME show no faults?

Not that I have seen.

Have you checked your brake lights?

[judgejon]

a. It does not matter - you are checking the brake light switch.

b. They are likely off if their lights are on.

c. Not in my experience.

d. It can occur on any 9x6 series car.

Loren -

I read this post and I am having a similar problem. I asked the dealer to look into it and was told that sometimes dust gets into the ABS sensors and to try and "hard brake" to see if it could be dislodged. They said that if that didn't work, I would need a $3,500. computer replacement. Needless to say, the "hard braking" didn't do a thing. Could my problem be as bad as the dealer indicated or are they just churning for dollars?

The dust line was just that a line. The ABS sensors are magnetic sensors.

Find someone with the Durametric software, a PST2 or PIWIS tester and have them check for fault codes and run the diagnostic test on the ABS/PSM system.

It would be unusual for it to be the controller - 9 time out of 10 it is a bad brake switch or even a bad MAF.

Is it possible for the ABS/PSM module to pick up on a faulty maf, and the DME show no faults?

03 C4S. the psm and abs started coming on and I ended up replacing the alternator. and the battery...

[milleruspp]

Loren -

You are awesome! I replaced the brake light switch and my problems are solved. It was a $13.00 part that took about 15 minutes to replace. Thanks so much for your assistance. :renntech:

[allan911]

My 2002 C4 just started having a similar problem. Every time I switch on the headlights, the ABS & PSM warning lights come on. I turn off headlights, re-start and the warning lights disappear and never come on (until I switch on headlights).

I assume it is a light problem, not a PSM/ABS problem.

[G60KG]

Hi

I was driving into work this morning and the PSM and then about 1 sec later the ABS light came on. They both went off when I turned off the ignition and then came on again a little later. I read in other posts that this might be a brake light switch or a MAF, or perhaps somehing else. I'll check the brake lights as suggested later but wanted to ask ...

a ) Do I need to do the brake light check when the PSM/ABS lights are on, or at any time - i.e. do I need to wait for the lights to come on again before I can know if checking the lights is telling me anything

b ) If it is the brake light problem, is this only the lights coming on, or is PSM/ABS actually off

c ) If they do this "lights coming on, but resetting every time", is it actually a PSM problem - i.e. will PSM actually not be working

d ) Does this brake light problem as occur on a 02 C4S?

Thanks

Peter

I had this on my C4S. Luckily it was the brake light switch which cost me around £10 from the main dealer and took me a couple of minutes to replace. If I were you I would try this first as its such a cheap and easy potential fix.

[dsnow]

Here is a link. Had the same issue on my 02 C4S. Easy fix.

Thanks

soutahc4s

[allan911]

My problem turned out to be a bad bulb. the two filament tail ight bulbs, one of them had one filament burned out. I replaced that bulb and voila, problem fixed!

[Makulu]

My problem turned out to be a bad bulb. the two filament tail ight bulbs, one of them had one filament burned out. I replaced that bulb and voila, problem fixed!

Same thing bit me ... But now I have and extra maf and brake switch at least