Cross Post: "PSM Off" and "ABS" light's on - what to do?!

About a 1.5 weeks ago I went for a ride in my '03 986S and my "PSM off" light and the "ABS" light both came on together at the same time. I did not touch the "PSM" dash board switch to turn it off, but double checked the switch and nothing happened with the lights remaining on. I then pulled over about 5 minutes later and rebooted the car. The light went away for the next 2 hours of driving. During that time I turned PSM off and on without any issues or lights remaining on. Anyhow, so last night I took it out for a spin to check on the issue. I started the car, let it warm up and no lights. However, about a minute later when I dropped the E brake the lights came on again. I rebooted, lights were off and then they came on about 5 minutes later and stayed on for the remainder of my 30 minute drive. The car drove fine and there were no diferences in the handling. Any suggestions, comments, experience with the problem and/ or questions? Thanks, CSbox03s

I had the same problem with my 00 C4. It turned out to be MAF sensor.

since the PSM uses the ABS system and sensors to operate it is likely you have an ABS system problem only. Since it is intermittent it is likely to be a bad sensor or sensor connection. Possibly the sensor is dirty or blocked by debris. Try cleaning your wheels, brakes and hub area on all four corners. Might help, might not. Try getting the codes pulled with a reader, might help.

Thanks for the input. I assumed it was an ABS issue since when the lights are off the PSM works fine. I am in the process of getting the codes pulled in the next week or so. I will post my findings.

Had the same issue, MAF sensor fixed mine.

Did any of you have the check engine light on in addition to the "PSM off" and "ABS" light.

Mine acted the same way and it turned out that I needed a new battery.

had check engine, psm & abs. MAF fixed the problem.

I had this in the past too. Sounded like the craziest thing to me that I'd get those lights and it'd be related to MAF sensor. I cleaned the sensor and they went away a couple of starts after cleaning it. Andy

Both a bad brake light switch or a bad MAF can cause both lights. Brake lights are easy enough to check.

AudiOn19s . . . That is what I am thinking. I threw an OBD II reader on the car to see if there are codes for the MAF and no codes were thrown. I will check the lights and try to clean out the MAF before I get the car checked out next week. All . . . Thanks for the input. Extremely helpful and good to know this isn't a code for "car about to self destruct." Thanks again.

Sorry, I decided to choose logic to answer the problem. Looks like it is probably the MAF, what was Porsche thinking? Making it impossible to diagnose the car from the warning lights alone so you HAVE to go to the dealer? Crazy

I think that if the MAF is not working then the engine can not be controlled by the computer so... the PSM turns off since it won't be able to control engine speed properly. Just a guess.

Did you check your tire pressure? I had an air leak on one of my tires which triggered the ABS light to come on (I don't have PSM); tire pressure difference on front tires was 15 psi.

an02boxster . . . I was thinking along the same lines. Anyways, sounds like I have a list of things to do this weekend! I will take the time to investigate all the suggestions by everyone summarized below and will post results. In order of least to highest difficulty: - Check brake lights (weekend car, so haven't checked yet) - Check tire pressure - Check Battery - Check and Clean ABS sensors - Clean MAF sensor I will add as people give input. Thanks again, CSbox03s

I have the same problem since May. Durametric shows P1109, P0103 and ABS/PSM fault code 5525 (incorrect data transfer with DME). I tried the followings and lights still come on once a while. 1. Changed MAF sensor, 2. Cleaned throttle body 3. New tires, 4. Disconnected battery for 5 min 5. Cleared codes 6. Checked all ABS sensor connections There is no pattern when the lights come on. Thinking cleaning the ABS sensors, can it be cleaned? What cleaner? thx MTB

The ABS sensors are magnetic pickups at the wheel hubs sitting next to a round part with radial cuts around it. Not much to clean there. I did have a pattern of comming on. It was at about 4k rpm in any gear but first. Cleaning the MAF did no good Replacing it fixed it right away.

Here is where I stand with my list . . oh and I added another item: In order of least to highest difficulty: - Check brake lights . . . all working - Check tire pressure . . . .fine - Check Battery . . . . . . . . fine - Check and Clean ABS sensors . . . . played with them, light came on when started car. Rebooted, and now there off. I took the car for a short ride and no lights, but going on a longer drive tomorrow. So we'll see. - Fuses . . . . . . . . . . . . . . .fine - Clean MAF sensor . . . . pending above - Buy a DURAMETRIC this weekend!!! . . . this will make things much less stressful to diagnose! Also, check out my original post on the 986 forums, judd944 through a link for a thread where they had the same problem. A lot of good info. http://forums.rennlist.com/rennforum...ght=PSM&page=2 Thanks, CSbox03s

My battery checked fine but voltage dropped just a tad too low when the ABS pumpmotor cycled. Only other clue was that the starter cranked the engine a bit slow. Didn't take note of this latter issue until I installed a new battery.

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Your buying a Durametric this weekend? Call me tomorrow.

My symptom was the same. The ABS and PSM lights would sometimes come on whenever I released the brakes. I had someone check the brake lights and they were not working when the ABS and PSM lights were on. I then shut the car off and restarted, which reset the system. The brake lights worked for several applications and when the ABS and PSM lights came back on, the brake lights quit working. I replaced the brake switch. It fixed my problem for about 12 bucks. The switch is mounted to a bracket under the dash near the pivot for the brake pedal.

Soooooo . . . after bk12 told me about iii911ooo's thread . . . The first time when I had someone checking out my brake lights to see if they worked, the "PSM off" and "ABS" dash lights were off. Recall, if I rebooted the car the lights went off, until I pressed the brake a random number of times. Well that time the dash lights were off. So, after bk12 mentioning the information from iii911ooo's thread I went back to repeat the same as the above ensuring the dash lights were on. This time I depressed the brake pedal numerous times unti the lights came on. It maybe took ~10 times of depressing the brake, where as the first time I only depressed the brakes 3 or 4 times. Sure enough the lights on the dash came on and the brake lights flickered a bit and went out with the brake depressed. I depressed the brake again and the lights did the same thing, flickered then went out with the brake depressed. To double check, I rebooted the car. The dash lights were off until I depressed the brakes ~10 times again. The dash lights were on again and the brake lights did the same, flickered and then went out. At this point a preliminary diagnosis is the brake light switch not functioning. I will try to change it out tomorrow evening. I will post what happens. Oh, and I guess I can call Rennlist my Durametric until I get one. Thanks, CSbox03s

Problem solved . . . . .Bought a new brake light swtich. Went to go replace it and checked out procudure in shop manual. The first thing it says is to try resetting the plunger in the relay prior to replacing the switch. This is done by depressing the brake, pushing in the plunger and turning it 90 degrees. Apparently this "plunger", which is self setting, can get stuck and needs to be reset. It worked! Drove about 60 miles the next day without any lights coming on. Now I have an extra brake light switch. Thanks to all for the help, CSbox03s

Can you post the part # for the brake light switch? thx

MTB . . . .I apologize for the delay in posting the part number for the brake light switch! Here it is: 996 613 113 02 By the way, drove for about 2.5 hours with no lights on the dash. Thanks again, CSbox03s

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2.5 hours...glad to see you are getting out to keep the rig from dryrotting