wineguy

Good afternoon,

I just purchased my first Porsche about a month ago. 2006 Cayenne, referred to as a 955 on here I believe. This site has been a great help. I purchased an aftermarket backup camera, head unit, Nav-tv Most HUr unit, and steering wheel controls. I was able to (more or less) successfully install everything, but am not getting any sound. Looking at the Fiber Optic cable that hooks into the MOST HUR unit, there's no light any more. I'm afraid I may have popped a fuse somewhere or pulled it and disconnected it. Where does it connect? It looks like it goes up towards the Instrument cluster, but I'd rather not take apart more of the car than I need to.

Thank you to anyone who can provide answers or a place I can find more of them.

deilenberger

The cable goes to the rear of the PCM (radio/nav/unit) - it is a directional loop. It is very easy to connect the wrong way, and when connected the wrong way it's not going to light up and work.

Did the MOST HUR give good directions on which cable to plug into which hole on the cable end? If these are reversed the loop is broken, no light will travel around it and nothing will work.

Adding a bit more..

EACH device on the loop has a transmitter and a receiver. Each cable must be connected at one end to a transmitter and the other end to a receiver. If both ends are connected to the same sort of port (transmitter or receiver) the light won't turn on and the computer bus won't work. The loop consists of the amplifier for the speakers (located in the rear storage compartment on the right side) the Bose woofer under the spare tire (if so equipped) the CD changer - also located in the rear storage compartment if so equipped, and the PCM. Several items are optional - and if not fitted a feed-through fitting is located where they would normally be - which just allows the light to go in one end and out the other - making the loop continuous.

One other thing that MAY need doing - is having the PCM coded so it knows that there is a new device on the loop. My old 2006 was pre-coded to think it had a CD changer even when it didn't. The Dension MOST bridge took the place of the CD changer in the PCM memory, and didn't require re-coding of the PCM. Earlier models may require the dealer to hook up a PIWIS and code the PCM to recognize it. That should be in the instructions that came with the MOST-HUR unit.

Good luck..

wineguy

Thanks. The directions weren't great. But I'm fairly certain that everything was done correctly on the PCM side, I'm thinking that something might have happened on the other end, and am wondering where the cable leads, are there any connectors that might have come loose between it and the amp (and is the amp in the back of the car)? Thanks again.

deilenberger

You may want to check the subwoofer connections. PITA to get to. And the amp is in the right side storage compartment in the car. If you have no CD-Changer back there - there is a turn-around connector also located back there. It is a royal PITA to get to these since the connectors are on the back side. A mirror is quite helpful.

deilenberger

BTW - I noticed you mentioned "head unit" - are we correct in assuming you've replaced the factory PCM?

wineguy

Yes. I replaced the factory PCM. Thanks for the information so far. My main question though, is still, after the fiber optic cable connects to the PCM or after market head unit, which direction does it go. I think that whatever happened, happened up front, and I want to take a look up there. Is it on the left or right side of the dashboard.