PSM Issues

[955_turbo]

Hi all,

While I've been lurking here for a while I thought it time to post something and see if anyone here has a solution to my PSM issue I've been having.

The problem is that after about 30-40 minutes of highway speed (100-110km/h) on cruise control all of a sudden cruise control turns off, I loose all throttle and the dash beeps and displays PSM Shutdown Consult Dealer immediately (or similar words). At this point you must pull over as there is no throttle, stop and the engine is running rough and full throttle gives you a 200 rpm increase and that's it. Ok, turn it off, restart the car and all is well again with the CEL on. Once the issue starts it's a continuous problem in that I've had it re occur 1km up the road or it doesn't happen again for 30 minutes or an hour.

The problem is that after the 4th start the CEL goes off and the error is cleared so the dealer sees nothing when I get it back to him and of course says that there is no problem and tries to charge me a diagnostic fee. Ok, Durametric to the rescue as I purchased it to keep and eye on things.

Here's what I retrieved. Motronic: P1508 and PSM: 1314.

I called the dealer on Monday and they are still looking into but I thought someone here might be able to give me heads up on the problems or if anyone has had or heard of similar.

Cheers,

Simon.

[Loren]

P1508 Torque Comparison Function Monitor - Signal Implausible

Possible cause of fault

- MAF sensor faulty or at fault detection threshold

- DME control module faulty

Fault Code 1314 - DME Control Module

Possible cause of fault

Signal from DME does not correspond to expected signal (please read out fault memory).

Signal from DME does not appear on CAN drive (no signal/communication).

[955_turbo]

Thanks Loren.

P1508 Torque Comparison Function Monitor - Signal Implausible

Possible cause of fault

- MAF sensor faulty or at fault detection threshold

- DME control module faulty

Fault Code 1314 - DME Control Module

Possible cause of fault

Signal from DME does not correspond to expected signal (please read out fault memory).

Signal from DME does not appear on CAN drive (no signal/communication).

[bgist]

I'm wondering if there was any follow-up on this particular problem. I'm having exactly the same problem with my 04 Cayenne S - but the dealer(s) have told me that its not throwing any fault codes, and without a fault code, they have no idea where to go.

I can't imagine that I have experienced a full engine shutdown, and had the PSM light (and the 4wd warning) lights flashing a dozen times without throwing a single code, but multiple dealers have told me this, and I have no ODBII/PWIS to corroborate their story.

I'm just worried about an upcoming Christmas driving trip I have planned .. I can't think of a better way to spend the holidays with my family than on the side of the road, waiting for roadside assist to arrive.

[wvicary]

It's very hard to fault trace these problems without being guided by fault codes. The systems are so inter-linked that the intermittent failure of one system often affects many. Have you had the basic checked like battery and charging systems?

[jcb]

I have the same problem in my 2002 996TT.

1508 and 103....

Cleaned and replaced the MAF (have a spare).

Event: happened on track...with the instructor driving...abs got triggered...

Dirty/bad abs sensor???

And a loose intake tube/etc???

Thanks guys!

Jeff

[DUTCH VanAtlanta]

My 2010 Transsyberia is throwing an intermittent "PSM FAILURE" message in the multifunction display. The first time the dealer said there was a stored fault code related to the Yaw Sensor, and they replaced it. It did it again this weekend, after a leisurely trip to Costco. It disappeared after a restart and a short drive.

It's scheduled to go in for the third time on air suspension issues. I wonder what they'll find this time.

[the head]

Reviving this thread since it's happening to me as well. Only on cruise, but it also only happens on the DME that I have an aftermarket tune on. Error codes on Durametric are P1508 for the DME and PSM error codes are 1314 (DME Control) and 668 (Vehicle Terminal Voltage 30).

It only triggers going uphill when the transmission doesn't kick down - which makes for some drama on a bridge or the like. Last time I was able to throw it into neutral, cycle the key, and get it to restart while rolling to keep from getting run into. After reading the thread, I'm curious if anyone else was running another tune other than stock.

[bgist]

I thought I'd offer my $0.02 as well.

This has led to the following parts having been replaced (under CPO warranty):

PRC:

955-618-025-03 (Control Unit Trans) 348.63

955-624-601-01 (Servo Motor) 435.29

(3x each)

DMG code: 39780400002

Plus a number of times that I've been to the dealer (under CPO warranty) and they say there is no fault, and nothing wrong. (10+ times, 3 dealerships). This has been going on consistantly since I purchased the car in 2008.

The warranty expired last month, and its started again. Literally less than 30 days after the warranty expired. Wish me luck.