I own a 2005 Porsche Cayenne Turbo. Out of the blue the radio/nav system stopped working today. Screen goes from black to the 'Porsche' screen that is displayed when you first start the car, then black again, back to the 'Porsche screen'... Nothing works (radio, nav system, info/audio buttons etc.). I tried to see if any wires in back are loose or has bad connections - fine, unplugged just cd drive unit, still the same. Please any advise before replacing.

 

I have learned here if you hit 1 4 8 on the dial pad all at the same time it restarts the PCM. not saying that will fix it, but give it a try..

 

Tried - no reaction, even key is out, delay set to 15 sec it looks like after locking the doors it is still going from black to white Porsche start screen, tried 90 sec with key turned left, nothing.

 

I don't know how long you have owned it, but I believe your PCM is a 2.0 and from what I have seen they tend to need replaced. If you haven't had it too long ask your dealer to run the vin and give you the history. I learned alot about mine that way. I had to rebuild my CD rom, and I know others have had to replace the screen. If it goes to much beyond that, it may need replaced.

 

Did you try pulling your PCM fuses for a full reset? I believe it is fuses 8-12 on the passenger side fuse box which will disable everything in the Loop (sorry dont have the manual in front of me). I have an 06 with PCM 2.1 and the dealer replaced the PCM about a month ago, however they said they never actually identified a root cause to the problem and the same symptoms came back even after replacing the PCM. Through trial and error the Tech finally got it working, but it has over the past couple of weeks continued to due the same things you have described. Mine actually would turn itself on and blare the radio even with the key removed and car locked. I have pulled the fuses since then a couple of times and the system seems to work fine. I am still under CPO, and definitely glad after seeing the price of the new unit they installed. It was several thousand for the unit and that did not include labor.....

 

yes, unfortunately have done all those things, none of seemed to do anything to the unit, i just goo crazy how much i love my Porsche but when the things go bad for no reason, it is so sad.
Saturday came back with family was working fine, yesterday tried to turn on and boom surprise. Although i remember was maybe couple time before didn't pay attention when warranty was still on it would not turn on after couple min and car restart it came back to normal.

 

These little things are often fixed with a "reset" of the system.

Lock car
Wait 1 minute
Unlock car
Get in
Close door
Insert key (but do not turn it)
Wait 1 minute
Remove key and exit.
Lock car and wait
Unlock car and start.
Check system.

This worked for a funky radio issue I was having.


(From Scott C on rennlist)


...if it makes you feel any better I'm on my 3rd PCM unit. I'm "naked" not so hopefully it won't go south again while I own it!

 

simpleman325i's code work, although I also did what PutterMcGavin recommended:

My car radio wasn't working. It was glowing, like it was turned on, but no sound, nothing on the screen. Even with the keys out and doors locked, it was still glowing. I was afraid it was draining the battery.

I go into the car, key in the ignition, without turning it.
Wait a full minute.
Press 1 4 8 on the numeric pad, at the same time.
Magic...the radio makes some mechanical sound, like it was shutting down and then it goes from glow to pitch black.
I take the keys out of the ignition and lock the door.
I open the door and put the keys back into the ignition.
This time, I turn the key and start the car.
I press the radio switch, which hasn't worked the past 2 days.
The radio miraculously turns on!!!
I press the radio switch again and it turns off, like it should...

I leave my car, not worrying that the battery is going to die the next morning and not have to find a new stereo unit, at least for another day.

 

I tried to research about it. I have seen that there are a lot of problems with the pcm or stereo whatever you want to call it but mine seems slightly different , my head unit turns off for up to a month sometimes and then it turns on out of the blue and works great for a while then it'll flicker and turn off sometimes it'll come back on the next time I use the cayenne other times it'll work weeks down the road but I have noticed it works more often in the winter then it does in the summer which i found really odd my dash screen always works but flickers a little and the heat/ac acts weird as well it'll go high and low randomly everything started to happen at the same time , could it be a battery issue or something bigger or what?

 

I put one used replacement in mine for $500 used that lasted about 6 months. :-( Then used one of the big name internet stereo dealers to put together a replacement setup.. The MOST is a problem but there are some convertors out there. You will loose the Bose EQ system. I wasn't happy about that but after a few months I decided that system is adequate. not great but good enough. sigh

I did get a lot of new features that even Porsche hadn't thought of in 2005. A nav system I can update, internet, decent Bluetooth, file and music sharing.

 

​​​​​​Thanks man!

 

*Any help here guys would be appreciated...My PCM radio and ac/heat wont turn on.The car runs great has 12v. battery replaced..Fuses all good 148 press nothing,,new batt on keys and they don't operate locks nor hatch..Help! now car starts and will not move in drive or reverse...

 

really hard to troubleshoot a car you cannot see and check.
Will help if you have diagnostics solution like Durametric, that will give you codes to focus attention on areas of suspect.
Do you have that? Without codes, it is really shooting in the dark.

 

I appreciate that..any specific VAG tool part # (90% of duametric is ok for me)for this cayenne instead of putting more $ out for a durametric by chance?

 

I could not comment on diag tools other than Durametric. I have the Enthusiast and works perfect for me for all my Porsche cars needs. You can get used from forum, sometimes get a great price.
Check eBay. Do not know pricing on other products. Whatever you use, not having one is very hard to repair, and one ends up swapping a whole bunch of parts because they do not know the specific area of trouble.