jrlecroy

I recently have aquired a "gremlin" in my 2005 CS with Nav.(now out of waranty) The stereo and navigation only work if it is hot day. In early am the system display shows "System Error: Amplifier, Navigation not found". Once the car sits in the sun for awhile, life is good again for my Peppa. Dealer kept the car for a week and ran some diagnostics. They wanted to replace the PCM (for about $2200) and proceed from there...suggesting that it might not fix the problem.They also said that I would have to replace my navigation system to upgrade to the new PCM (another fist full of $$). I declined their generous offer. I have looked through most of the posts here that relate to this problem and would like to check the fiber optic connections at the head unit, nav., and the amplifier but have not found any info about accessing the connections at the head unit. Any help with removing panels to access these points of connection would be appreciated! Other thoughts on debugging also appreciated...

jrlecroy

Update: I have been able to remove the head unit and I can see the laser signal from the back of it shooting into the outgoing optic fiber on the MOST loop. I also was able to remove enough of the rear panel assembly to access the amplifier. When I remove the fiber optic connector I can also see the laser light coming out of the incoming line to the amplifier. When I then pull the connector from the back of the Nav DVD player under the passenger seat however, there is no laser signal seen in the cable running from the amplifier into the DVD. I am assuming that I either have a problem with the amp/or power to the amp, or a break in the line between the amp and Nav unit. Does anyone know how to test and see if I have a loss of power to the amp when it is not working?
PS. Had to stop problem shooting since it is now hot outside again and everything is working fine!

porsche52

Ok, if this car came into the shop that I work at, I would do the following.
Perform MOST diagnostic ring test with PIWIS tester when fault is present (cold ambient temp). The results of this test should tell me what control unit (PCM, NAV, SAT, AMP, CD etc.) is causing the BUS to fail. The control unit in question will either be electrically or optically faulty. We have a fiber optic "jumper" plug that we plug in, in place of the suspect faulty control unit. If the system comes back to life and operates as designed with the jumper installed, then bingo, you verfiyed the problem. Replace that item. Do not throw parts at this problem, it is a very easy system to diagnos for Qualified techniticians. Sounds like the Amp is bad, they have been known to fail. Like I said, it would take 10min. for a good tech to veryify this with the PIWIS tester when the problem is present. Feel free to PM me for more MOST system details.

ltc

^ + 1

jrlecroy

Thanks! I'll do just that...then I'll contact my service center to see if they did that.

jrlecroy

I think that I have isolated the problem in the amp for sure. It was in "error" mode last night and I stuck a blow drier on the back of the amp for less than 5 mins and all of a sudden I had music again! I guess the cheapest fix would be to install a hair dryer connected to a temp sensing switch! $25 vs $1300?
Found an amp on Ebay from an 09 CS..anyone know if it will fit my 05?

ltc

Very strange.

There is a temp sensor in the amplifier which shuts OFF the amplifier if the internal temp gets too high (this was initially designed in to protect the fiber optic transceiver (FOT) against outgassing/fogging on the plastic lenses....80degC was the initial warning point), but I don't recall any minimum temperature shutdown.

My best guess would be a cold solder joint (not unheard of given the pitch of some of the SMT parts and the mechanical stress placed on the PCB during assembly and use) and simple thermal expansion (via the hair dryer) re-establishes a connection.

The amplifier is fairly easy to disassemble..you only need a single Torx screwdriver so if you are electrically inclined, you could do a quick visual on the solder joints (although they are under a thin layer of conformal coating)....you could also try a 'tap' test with the amplifier connected but in this "opened" state to try and narrow down the search.
Inside you will find 2 circuit boards, one analog (power amplifiers) and one digital (microcontroller and DSP)....my first place to look would be the digital board.

rob020880

I am having the same problem, I even have an extended warranty but porsche says anything to do with the pcm is not covered. I also have the 05 s.

Any chance this might be a simple fuse issue?

Where is the amplifier located anyway? I want to try your blowdryer idea.

jrlecroy

Amp is located in the rear right wheel well-it takes a bit of work to remove the interior panels to access it. I found some helpfull posts here on removal of those. You can see it and try the hair dryer simply by removing the access panel on the right rear section of your "trunk" and looking up into the space. You will see the bottom of the amp and connectors on the rear. Point the dryer up there towards the back of the amp for a couple of mins and see if you get any results. Note: I did this because I had obvious problems with the system in cooler temps only. When it warmed up enough I had tunes!

volkaksoy

Hi, I brought a second hand Cayenne S 2004 last year and it was summer and didn't have any problem. Just after two months I also started to have problems when the car was cold. After I drive the car for half an hour and stop the car, then start again. The problem was gone.

Since a year its was like this. At winter I took the car to Porsche service put they couldn't understand and verify the problem.

All the sound system was failing and the phone wasn't appering on the board but it was still working. I used it but since the sound system was dead, no handfree.

This situation continued until last week. Last week it also gave an error as "Navigation, Amplifier, Phone, Cd Changer etc. error"

Today I took to a radio service. The guy bypassed the amplifier and the system turned back. So certainly there is a problem on the amplifier but the nav is still dead. He said lets try to find an amplifier an solve the sound, then maybe a hard reset can solve the nav or changing the amp will solve it.

I also remember that I was facing sometimes problem with sound when I was listening music, all system seams working, no error but no sound and I was checking if I mute the system but no, then it was turning back.

I'll also take out the amplifier and see if there is any thing I could visually see on it.

PTEC

An amp from a 2009 won't work but up to 2008 should work.

EnigmaWmn

I've had that error come up once. Restarting the car took care of it and it hasn't been back.


YET!

ltc

You're fine...you are on Larry's "good list".

Eventually Porsche may figure out that local RDS transmissions can send commands to things like...oh, I don't know....amplifiers.

EnigmaWmn

That makes me wonder. Whose s-t list have I been on, with all of the previous repairs?

ltc

That was probably the evil Dr W's list...