porschedog

Two nights ago on the way home from the office, in a light drizzle and 64 degree temps, as I rounded a corner my ABS and PSM indicators lit up. Used PSM button to attempt to override (on/off) - no reaction. Drove home, no big deal. Turned off the car. Counted to 5, restarted. No lights, and now when I press PSM button it goes off, then back on when I press the button exactly as it is supposed to do.
I then took a "spirited" drive involving trail braking around the neighborhood during and after which the indicators stayed off.
Alternator looks like it is charging, battery is showing 12.7 volts and brake fluid is 100% full.

I am suspected this is not a big deal and "just happened" I'm driving the GT3 to the office and will take the 996 out for a longer loop on Saturday.

Any thoughts on this?

DBJoe996

Your car didn't like the weather so it protested! No clue...anomaly? If it doesn't repeat then you would just be chasing ghosts.

Mark I

One of the first suspects is the brake switch failure, which begins as sporadic episodes as you describe, then goes out completely.

Dennis C

porschedog

Thanks for the input; switches & sensors are on my suspects list. Tires are new fwiw.

DBJoe996

I remember reading about some other ABS/PSM problem, and it turned out to be a flaky/faulty brake light bulb. So might want to put that on the list of things to check as well.

Gretch

As hokey as this sounds, I had a bad MAF which triggered the PSM system to go off, especially when I put the car through a quick throttle action. I used a code reader and got enough code data to confirm a bad MAF.

Replaced the MAF and all good.

Jfrik

I had the same issue, including the fault going away for a period of time. Mine turned out to be the steering angle sensor.

Durametric found the fault right away, might be worth having it checked. Best of luck, I hope it is nothing, or at most the brake pedal sensor.

Dr_Strangelove

I've had this happen for both the steering wheel angle sensor being triggered when I bought the car with a bad alignment, and a wheel speed sensor that was not fully plugged back in after a service. When I was researching this issue for myself I found that the PSM/ABS warning light combo indicates a whole laundry list of faults. I'm hoping yours is something easy like mine.

FWIW - If it's your brake switch, (a common cause,) you will notice a direct correlation between your foot on the brake and the lights on the dash. If it's intermittent this could be annoying to pay attention to. My wheel speed sensor fault illuminated with ignition of the car, it was instant and constant. My steering wheel angle sensor fault took 5 minutes, but then was constant and didn't clear until I turned the car off.

Good luck!

porschedog

More great suggestions - thanks! I plugged in the code reader too, just because, but no codes showed. I'll check MAF and bulbs and do some research on the steering wheel angle.

Rennlist is an amazing community.

charlieaf92

This happened to me on the drive home from buying the car. It was early morning and slightly rainy - the car had sat in the hotel parking lot overnight - and I decided to open it up a little. The lights came on around 119mph so I backed off, pulled over, restarted the car, and they've never come back on. I'm thinking it was some kind of misread due to moisture on the sensors.

human911

porschedog

I was a bit under the 119 mph mark, lol

Checking brake switch ASAP

porschedog

This story has a Happy Ending

After replacing MAF sensor (fixed it for 3 months), then the brake vacuum sensor thingy ($120 down the drain - zero effect), I Finally did the $20 brake switch replacement.
The original brake switch was definitely not quite right, as the spring seemed to have compressed a bit and stayed that way.

ABS & PSM lights are off.

wyovino

Glad you found the cause. It's not easy with these cars. I had the ABS/PSM lights when I forgot to reconnect my MAF after removing and replacing my airbox.