cayenne pcm wont turn on with key turned

[Cyttse]

On 2017/1/7 at 8:01 AM, troyporsche said:

 

Yes the jet washe is working but the wiper just not moved.

 

 

I just thought maybe that was due to the xenon ballast?

 

I just changed the ballast and the starter then after all the pcm and wiper were not working. 

 

I bought the ballast from xenonland. Well I did order by the factory part number but endup they sent me the part 970.618.143.02 instead and they told me that was the latest part number. My mechanic told me they couldnt find the xenon unit and the pcm in the computer now...

On 2017/1/7 at 4:44 PM, lewisweller said:

Cytte refer to my previous post you must be 110% sure the battery is in top shape or you are chasing your own a*s around in a circle. 

 

Use a battery maintainer for a night and check it in the morning, or just replace the battery if it doesn't check out. 

 

You know when I had a no start situation I strip out my starter and found it to be fine, but I stripped it completely down cleaned up everything, bench tested and put it back togther. I subsequently found the alternator was jammed causing the no start. But anyway the point I'm making is after I got it all Fixed the car started so much better because I had simply cleaned up the starter motor internals, brushes and all cable connections reducing the resistances. 

 

This car is the worst for anything remotely voltage drop related. As the winter has come more and more people have posted with weird stuff happening and quite a few just needed a new battery (but not all). 

 

Cytte is it possible your worn but working starter was affected by your possibly failing battery? Maybe just a new battery and a starter clean up would have been a Fix as opposed to a new starter which will run on the failing battery because it's new and has less internal resistance? Alot of maybes I know but you gotta think outside the box a little when faced with these conundrums. 

 

Maybe your pcm is fudged and I'm talking nonsense. 

 

Thanks for your reply.

 

I had my new batt replaced in just 3months ago thats why I didnt think about that was related to the batt before. 

My starter seems working badly before as it needed more than 5 times to make it start. The new one seems working well now.

 

 

Anyway I ll try to measure the the voltage again tonight and see. Or I ll disconnect the batt for awhile.

 

 

 

Disconnected the batt for a night but no luck.

 

Will try put on a new batt or what next week. Annoying.

[Cyttse]

I finally figured out why the PCM and the wiper not working, it is the headlamp ballast!


I bought the ballast from Xenonland.

 

https://xenonland.com/productv/40573/hella-xenon-ballast-control-unit-for-porsche-cayenne-2007-2010.html

 

 

 

 

They gave me the part 97061814302 and insist thats compatible to my cayenne though I believe the part should be 955631194xx.

 

 

 

I unplugged the ballast and everything back to normal including the pcm and the wiper.

When I plugged that in, the headlamp worked but some of the electronics control unit were lost and could not be read from the diagnosis.

[ekstroemtj]

I dont get it really. What has a wiper and the PCM to do with a failing headlight Ballast :-(

[Cyttse]

No idea. Thats from what I observed.

 

Now I took off the new ballast and everything back to normal.

[troyporsche]

the ballast in my cs works fine. its weird that the ballast can effect the pcm and wipers. i replaced the battery still no joy. when the bonnet is open i get no warning on the cluster i wonder if the bonnet switch is broken and thats why the front wiper not working?

[Cyttse]

Sometimes the bonnet switch do affect the wiper, when the computer think the bonnet isnt completely locked it will stop the wiper motor from working.

 

There should be some breach of the circuit for making the pcm not working properly.