FlyYellow

Hi,

My brake light no longer works on my tow hitch wiring. I purchased a simple 7 to 5 flat converter tester. The five wires are:

Ground
Tail Light
Left Turn
Right Turn
Reverse

Now I would imagine that if the brake pedal is pressed both the left & right turns should light up. They don't - nothing lights up. Am I missing something here??? Any advice?

I'm thinking that perhaps the trailer module controller may be screwed up. I know it used to work. Is there anyway to reset it?

ltc

Am I correct in assuming that the vehicle brake/directional and reverse lights work with and without the trailer plugged in?

Am I correct in assuming that the trailer lighting has been tested with a 12v supply?

Am I correct in assuming you have tested the 7 pin plug directly, without the 5 pin adapter?

Am I correct in assuming that you have verified the internal connections/wiring of the purchased adapter or tried a second/known good unit?

Am I correct in assuming you have tested the brake switch signal under the dash via the 4 pin connector?

Am I correct in assuming that you have checked all fuses in the Cayenne?

ltc

Do you have access to a PIWIS? That would interrogate the factory (Westfalia) tow bar control unit.

FlyYellow

Lewis - thanks all good questions... Here is what i got:

Am I correct in assuming that the vehicle brake/directional and reverse lights work with and without the trailer plugged in? YES

Am I correct in assuming that the trailer lighting has been tested with a 12v supply? YES

Am I correct in assuming you have tested the 7 pin plug directly, without the 5 pin adapter? Not sure on this one. There is no independent brake light in the wiring - i thought just left & right turn signals that double as the brake light. They independently work for turn signals, but when you push the brake pedal neither have any voltage.

Am I correct in assuming that you have verified the internal connections/wiring of the purchased adapter or tried a second/known good unit? I have two adapters. Neither work - although one is the 7 to 5 LED adapter for LED brake lights.

Am I correct in assuming you have tested the brake switch signal under the dash via the 4 pin connector?

No - have no idea what this is - tell me more. Is this the circuit or logic box that combines the brake signal to left/right turn signal wire? If so this may be my problem. How would you test it?

Am I correct in assuming that you have checked all fuses in the Cayenne? Yes did that!

Thanks so much for your help - much appreciated.

FlyYellow

ok i'm pretty sure it is the brake switch signal - is there a way to check that? And is there a way to reset it?

ltc

What type of brake controller is plugged into the under dash 4 pin connector?

Or, is this trailer surge brakes (Trailex or boat)?

What type of trailer and lighting configuration?

Has this setup ever worked before or is this a new setup?

RL member JFScheck has some excellent brake controller install/wiring pics and threads for controller installs. Try a search or send him a PM.

ltc

How long have you owned this P!g?

Do you know if the factory tow bar control unit ever worked?

Do you know if it has been coded for US vs. RoW ?

Are you allergic to shellfish?

ltc

Shorted trailer wiring?
Blown fuses?

Which fuses were blown?
What was the short between?

It is possible that you might need a new 1D6 tow bar control unit.
Very quick PIWIS diagnostic and replacement if that is the case.

ltc

There have been a couple of DIY threads here in the P!g Pen showing where the 1D6 lives (passenger side rear cargo compartment wall) and how to access it (PITA to remove trim panels).

There is a chance that even if you buy one (Suncoast, Sunset, etc), you may have to have it updated via PIWIS. Very quick and inexpensive.

Apart from that, you could try over on Loren's website