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No audio, nav, telephone, cdc after empty battery?

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Hello everyone! 🙂


I'm not sure what is happening here...


The car was parked for a while, and the battery had been flat for some time. Now, I have replaced the battery with a new one, and during a test drive, I noticed an error in the PCM and no sound from the radio. Mute/Unmute/VolUp. Nothing.

The PCM reports: "System error: CD changer, telephone, navigation not available."

The car has all these modules and a BOSE system/amplifier.


Disconnected the battery again, waited, and tried again. No change. I checked the fuses, and the front right #4 and #36 (5A) were blown.

When I replaced them, they blew again. Telephone module? Unplugged the module under the passenger seat, put the fuse in: OK.

The module is broken, or so I thought. I bought MOST fiber bridges and inserted one in place of the telephone module.


Unfortunately, no changes. PCM same error, no navigation, CDC, and audio.

Then I suspected that the amplifier was causing problems (the PCM shows no amplifier, not even via MAIN+TRIP menu).

I bridged the amp too. PCM same error. CDC and navigation do not work.


I tried to trace the fiber connections. PCM -> AMP -> CDC -> NAV/DVD -> TEL should be the loop. The AMP connector lights up red (from PCM), and if I bridge it, the next one in the loop should light up red, but no plug turns red that I could find. Not the CDC, TEL, or NAV.

I have bridged all devices piece by piece but cannot find a plug that would continue in theory after the amp.

But with my phone lamp could I light my way through the connectors...?


The PCM, for some reason, does not complain about the amp.


Nothing changed in the car, except the new battery and the telephone module that was blowing fuses.


Does the PCM error need to be cleared to test the NAV and CDC?


I don't know where else I can look, apart from having the error cleared at the shop. Thank you very much!


Porsche Cayenne Turbo, 2005.

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