Frozen PCM 2.1 (Surprise, Surprise)

[McQuattro]

I've got a temperamental ***** for a PCM. It's the 3rd one that's been in this car, and it is JUST out of warranty.

The problem is: The PCM froze on the trip computer screen, stuck on one radio station, and NONE of the buttons work. However, the knob wheels work. So I can adjust the volume, but I can't turn the PCM off. I can scroll though the menu, but can't select anything.

I've been through the gambit of cutting power to the PCM in hopes to "reset" it. I've disconnected the battery. Disconnected the battery, and the fuse for the PCM. I've disconnected the battery, bridged the positive and negative cables, and removed the fuse. I've done all but take out the PCM and put it in solitary confinement far from the car and it's power source.

The last PCM was installed Oct. 2008, so it was already loaded with the newest software update for these PCM's.

Can the PIWIS get into the PCM and do a soft reset, or is the whole PCM going to have to be replaced again? (the dealer's only course of action)

Does anyone have a line on a company that rebuilds or refurbs these units? Or are there any alternatives to replacing the whole module?

The 997 GT3 Cup cars never have this problem.....

Thanks!

[355bhp]

If yours is an '05, give this a try: http://www.renntech.org/forums/index.php?s...mp;#entry155279

Edited October 22, 2009 by 355bhp

[porha]

Hi,I had a cayenne S 04 with PCM 2,and external hand set(numbers) was not working when was on phone mode.

I have PST2, and was trying to code external hand set for phone to present,before and later was no fault text,and than:no sound on any mode,rotary buttons not working,buttons was not working only ON/OFF,display worked.And on steering wheel was working mute button and note button.

I connected the car with computer and start looking for mistakes on settings and codings.First when I tryed to do the test on 'most component units list' the units was not recognized, only PCM MMI was found, and most required and most actual unit list was unequal.then I entered the devices that was never entered PCM gateway,navigation,cd changer,phone and made the unit lists equal, but when I did the MOST COMPONENT TEST again the lists was unequal again only devices was entered correct now.I was changing the settings all day and did the coding as it should be basic on car,every setting tryed for 5 times,all day the same.I then I tryed to do the lists match for 6th time, and some scratching came out from speakers,I turned off and on the radio and sound was working,buttons to,everything started to work,at least,phone and navi too.before didn't work.Now everything is working for one week and I hope it will stay that way.

No logic,,The PCM was not the first one,was changed in 2006,and no coding or bad coding was made with computer,maybe that was the problem,and when I connected the car everything colapsed.I don't know.

sorry for my english

[RFM]

Have you checked all the PCM related fuses? In the back of the PCM and in the left fuse holder (foot well)?

[AP 997S]

Wow . . . It does seem odd that you've had the same sort of problem on (3) PCM units. I would tend to look for the real source of the problem. Hard to believe that (3) PCMs fail in the 'same' manner. Was the problem the same on all (3)???????

Someone already mentioned the fact that early build 2005 997's have some 'uniqueness' regarding the PCM and it's software and the Bose Amp. It doesn't sound (no pun intended) that this issue is your problem. You might in fact put in a later build PCM that isn't compatible with the rest of your system. Just a thought!

If they were dealer installed and even if your car may be out of warranty there still might be some residual warranty on the actual PCM unit. If you bought them off eBay or some other 'questionable' source you might not be able to get the dealer to 'buy-in' on the problem.

Good luck and keep us all informed as to your ultimate fix.

[berty987]

Press 147 to do a soft reset of the PCM. If cycling the power isnt curing your problem you may need the PWIS unit to interrogate the device. Is the PCM original factory fit or an aftermarket install using a used or second hand part ?

The PCM is the timing device and main hub for all the most ring devices. If the PCM has a fault internally then it can get out of synch with the MOST devices causing conflicts. Its also important that the MOST ring has no breaks or damage / dirt at the juctions , this can cause the PCM to see devices dropping out of the MOST ring. The PWIS unit allows the technician to declare the MOST devices in the PCM , the PCM then looks for these devices. If they cannot be found you get an exclamation mark next to the device on the PCM MOST menu (press main and trip together to access this). The devices can sometimes not be recognised if the MOST optics are damaged or the devices are out of order on the MOST ring ie not corrected in the correct sequence.

[Zylex]

The 997 GT3 Cup cars never have this problem.....

probably because they don't have a pcm? :-P

only a fool would buy a cup version with a pcm (don't know if its even possible).

reducing weight is essentially for race-cars like the GT3 cup ;)

[phillipj]

I think that was supposed to be a joke... ;)

[Guest omulghicitoare]

I have EXACTLY the same problem !!! ((

My navigation PCM2 for porsche cayenne says... System error: phone not found .. Press Confirm

and NO BUTTON IS working except volume ((

any one have a fix for this please ???

Edited January 8, 2010 by omulghicitoare