PSM and ABS Warning lights on

[TJH]

I replaced the battery in my 2001 996 C4 at the weekend, drove it for two miles, next time I started the engine the PSM ans ABS warning lights came on.

Was it a result of the battery replacement, if so what do i need to reset the warning lights or is it something else casuing these light to come on ......... ?

[Loren]

:welcome:

What you are seeing is normal after disconnecting the battery.

In most cases they will go out again in a few miles and a few re-starts.

If they do not, then check your brake lights - a bad brake light switch can cause the same problem.

[TJH]

thanks

[georgios]

Hi,

I was away for 6 weeks and just started driving my 996 4S and the same thing happened. Twice actually and both times when I hit the brakes rather hard. I am glad it may only be the brake light switch. Just had my clutch, RMS and IMS replaced and had nightmares of additional huge costs. By the way....still have a minor oil leak and I am contemplating if its worth going back in there to change the RMS?!

[jasmus1]

That's interesting. I recently had work done consisting of a new RMS, IMS and clutch. Lately, when I am cruising down the road both my PSM Off and ABS warning lights come on. The warnings stay until I turn the car off. They come on when I drive it again, but only after driving for a while and not always. Could there be a relationship between this and the work that was done? It seems curious to me that I would have the same problems as georgios and it looks like we had the same work done.

[rb101]

For some reason, when the MAF goes bad and you go above a certain RPM, the PSM and ABS lights can go on.

[mobil1nsx]

Had same thing happen to my C4S.....2 weeks on vacation, came back car sounded like didnt want to start....started drove couple miles and stopped for gas...car sounded like didnt want to start but did. Got the lights mentioned above plus Engine light(fixed) and Drive to dealer warning..... drove it home, charged battery for couple hours...tested voltage off @ 12.6 and running at 13.8.....I tyipcally leave all my cars on 2 am battery tenders since dont drive them but every few weeks due to travel.

Hooked up DMetric, had abunch of misfire codes on various cylinders and cleared fault codes

Optimas/Die Hards/Bosch, tried them all...seems with infrequent driving and on battery tenders my batteries just dont last...must cook a cell or something in them.

I yanked out the old battery and put in a fresh new one.

Drove car around all day, not codes or warning lights...no starting issues....so assume another battery bites the dust...or was about to.

Lastly, in addition to the warning light similiarity posted above, I couldnt help notice the RMS/IMS notes.....yep same with me.....

This 02 C4S probably holds the record for RMS replacements....always a quarter size spot no matter how many times under warranty (New Warranty & aftermarket warranty) they replace it.....only good thing is they did the clutch for me buying the parts at 40K ish miles....

[jasmus1]

My warning lights vanished. Not sure why. Maybe the good karma I've been spreading around is helping. Well, maybe not, because now I have a new set of car problems (leaking coolant) that I will need to post to get info about.

[allan911]

I have a 2002 Carrera 4. when I turn the headlights on the PSM and ABS warning lights come on. I haven't checked to see if any tail or brake lights are not working, but it sounds like that may be the problem. When I turn the lights off and re-start my car, the warning lights disappear and never come back on.

[Loren]

I have a 2002 Carrera 4. when I turn the headlights on the PSM and ABS warning lights come on. I haven't checked to see if any tail or brake lights are not working, but it sounds like that may be the problem. When I turn the lights off and re-start my car, the warning lights disappear and never come back on.

Also check your battery - an old or weak battery can cause all kinds of strange electrical faults.

[allan911]

Loren, It was a bad tail light/brake light. I actually had two lights out, the small bulb and the two filament bulb (had one filament burnt out). It was the two filament bulb that was the problem. once I replaced it, the ABS and PCM warnings do not come on. WOO HOO! a $5 fix! (can't say that very often)

Mark