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Towing Electrics

STS

New member
Hi, I've just bought a 2006 Cayenne. One of the main reasons for going for a big SUV was the capability to tow my track day car on a trailer to events. The reason for buying the Cayenne - well, it's a Porsche and I've always wanted to own a Porsche!

I've plugged in my lights board and there's some strange behaviour going on:
  • Only the offside tail light works.
  • When I press then brake pedal both brakes lights AND both indicators come on (the indicators are lit solid, not flashing).
I know the light board is OK (tested on another vehicle) and I have checked the 13-7 pin adapter is wired correctly.

Any help/thoughts on why it's behaving like this would be very much appreciated.

Thank you!

Simon.

 
I used to get dodgy lights on my last Cayenne with the electric tow bar option. It had an electric adaptor to fit our old Ifor Williams trailer. As it was used infrequently I assumed it was a case of dirty or rusty connections so a good clean up and wiggle used to fix it.
 
I plugged in my code reader yesterday and looked at the AHK module live data. When the lights are switched on, the right taillight is shown as 'on', however the left it shown as 'not used'.

I can also see that when I press the brake pedal, the module sets (or detects?) both indicators 'on'.

To my way of thinking, 'not used' isn't a fault. It sounds more like a configuration option to me. Do the AHK modules need coding?

Is there a chance I am over thinking it and it's a simple cabling issue (such as a short)?

Thanks.
 
I think you are overthinking it. You dont say if you tested with the board attached if so then Not used simply means that it hasnt detected anything on that circuit. Would be worth trying with the board detached

I can think of a no of issues
1. The adapter isnt wired quite right or has a short in it. Not always possible to tell untill ypu put a load on it. the Porsche one is only £14 so that might be an option. Its not beyond the bounds that Porsche have rigged it so that you have to use their adapter
2. The board isnt wired quite right but will work still work on older style electrics.
3. If the board os old fasioned non led then the mix may not work

can you find someone with another trailer and try that?
I have seen multiple examples where a trailer works fine on one car but not on another and it is usually down to wiring or corrosion.

 
Thanks Steve.

"I think you are overthinking it." Hopefully! :)

The board was attached during all testing. This is the first time I've dealt with a car with a towing control module, but I found out that the module won't send power to the socket if it doesn't detect a board.

The board is approx 1 year old and 'off the shelf' rather than something I have made. It's made by 'Ring' and has bulbs. Theoretically, therefore, it should be correct but point '2' noted. I don't have access to another board unfortunately.

I have continuity checked the 13-7 adapter - it seems fine, and no shorts. I will double check it whilst sourcing a Porsche unit. For that money, it's well worth trying.

Cheers!

Simon.
 
I had some similar peculiar effects using a bike rack light board. I knew my Cayenne electrics were ok because every thing was fine when attached to my caravan.
Turned out it was something dodgy in 13 - 7 pin adapter I was having to use with the light board. Had the board rewired to a 13 pin plug and all was ok.
So recommendation is don't use an adapter, get a proper1 3 pin plug.
 
I was thinking along the same lines after buying the official Porsche adapter and seeing no difference. So I bought a 13 pin Sealey tester and that shows the same results as when I use my light board.

It is looking like a Cayenne wiring or AHK problem unfortunately. It would have been great if it had turned out to be the lightboard or adapter, but it's not looking that way at the moment.

Cheers! Simon.
 

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