master_328

Hi folks,
I have no more sound from by Burmester HiFi system (PCM is working ordinary), no picture from backup cam in display and I cannot turn on OEM rear seat entertainment system left & right of my 2010/2011 Cayenne 958 TT. No blown fuses. No fault codes with my launch obd codereader. After doing some research, there maybe a problem with MOST bus? I don`t really know where to start. I checked the rear side panel on the right side, there is no water from panoramic roof visible - which seems to be a common issue. Car is kept in garage all time. Any help is appreciated.

Daveheardt

Hey!

I am new to this forum (found it yesterday) and I am new to the Porsche ownership scene as a whole. So don't consider me an expert, just a "regular Joe".

From what I understand (mostly from reading workshop manuals) the PCM is responsible for handling pretty much everything you listed - sound, backup cam, rear seat entertainment. While the water drains do indeed seem to be a common problem, what you are describing is unlikely to be water related, in my opinion. If it was water or a fuse - the wiring would be shorted, leaving you with malfunctioning PCM, which ultimately would render error codes (one would expect). Since that's not the case and "PCM is working ordinary" as you say, I suggest you check the cable connectors on the PCM, the ribbon cables inside the PCM, and if you can - the transistors inside.

According to a VW Touareg owner friend, the cables don't always throw error codes when they don't connect well.

I hope this helps and it's an easy fix for you 🤞

master_328

Some more information from Porsche diagnosis (I`m sorry, it`s in german):

Dcdoc

I'm kind of in the same situation. Just uploaded a post about it.

I don't have rear set entertainment but I have the TV-Tuner which you should also have.

In my case, I also get the error 800D plus 8023 and 8024 regarding the Burmester rear and left.

Do you also get a message on your PCM that TV device not available? And every time it comes up, which is every 15-30s,you loose sound until the message disappears from the screen?

Cheers

master_328

I don`t get any message on my pcm. Everything looks standard. But there is absolutely no sound, no backup cam and the monitors of the RSE won`t start. I already removed TV Tuner and checked plugs & cables. Everything fine so far. I talked to a PCM repair guy today and he told me that the TV tuners usually don`t make problems. Referring to him, the gateway behind the PCM main unit should be checked. Didn`t remuve the head unit yet, because I`m waiting for a used working TV Tuner to be sure.

Dcdoc

I was about to take apart the panels to check if the TV-Tuner was the source of the problem.

I removed the PCM today as I´m in the process of updating the drive to an SSD and installing Carplay. The gateway is located in the PCM itself or is it another part?

Have you tried disconnecting the TV-Tuner/Rear end entertainment fuse?

master_328

I don`t know how this gateway looks like. I couldn't find in parts catalogue.

Yes, I tried disconnecting and also reseted the PCM 3.1

Dcdoc

I´ve reset everything plus today I went and re-updated the PCM to the latest version and still wasn't working

master_328

I just removed the pcm 3.1 head unit. Plugs + wires also seem to be fine. But I also cannot play a CD. It tells to load the CD and then the Radio/Tuner monitor is showed again.

Dcdoc

As soon as I´m able, currently, my car is in the Workshop, Im gonna check the cables that are going to PCM for continuity with a multimeter. You can try and do the same to see if the wires are good. That means, the wires are connected and not broken in between. Is not 100% as if they are shorting with another thing, they could have continuity, but at least it a quick test, just in case that would be the issue.

Dcdoc

Any news from your end? I haven't been able to do anything more on my end

master_328

No news yet. Had the car in porsche garage, they tried to use another tv-tuner and amplifier, but without success.

Dcdoc

Thanks for the feedback and sorry to hear no news.

My car is still getting fixed (Transmission), so I haven't been able to find anything else on my end. I should get it next week.

Have you checked how your battery is without the ignition on? What I´ve been researching about is parasitic voltage/current. I have the feeling there could be something wrong with the electrical wiring. I will also check for continuity on the PCM cables.

Check this video out in case you also want to try it

Dcdoc

What did the Porsche Zentrum said were the next steps? Did they mention it could be a faulty PCM?

Dcdoc

Can you link the Thread? I havent been able to find it.