No Power on 7 Pin Trailer Plug

[LOG]

I Posted a similar question on the Winnie Owners Forum.
I am posting the question on this Forum in the hope that some of the very knowlegable members on this Forum do not read the Winnie Owners Forum.

When the Motorhome brakes are applied, there is no power to the turn light/stop light pins on the 7 Pin Trailer Plug.

The Tow Fuse Panel does not have a fuse for stop lights, but has a fuse for the left turn signal and a fuse for the right turn signal. Both of these fuses tested good.

All lights work on the motorhome. Tail lights and turn signal lights work on the toad.

Winnebago Customer Service and Freightline Customer Service have not been able to help.

[Jim_HiTek]

Since you don't find a brake fuse, then I think that in that case, your turn signal lights should light up when you press on the brake pedal, both at the same time, indicating braking. If that's how your system works than, yeah, you should have voltage at both pin #5 & pin #6 at the same time when you press the brakes in the RV. (And one or the other pin when your turn signals are operating).

If you have separate filaments that only light when braking though, than the towing connector should have 12 Volts on pin #7 and pins #5 & #6 won't have voltage. If that's the case, but no voltage on pin 7, then you might have a remote fuse block somewhere. Those bulbs would be 1157 with dual filaments.

Of course check the wiring to the 7-pin as it's cable or wires hang down sometimes and can be torn out by road debris.

[LOG]

Jim, Thanks.

You are correct. The turn signal lights should have voltage at the stop light/turn light pins when the brake pedal is depressed. In my 7 pin connector, they are pins at the 3 and 9 O'Clock positions.

They do not have voltage. That is the problem.

So, what is wrong and how do I fix it?

[David 70]

Best is to start at the plug and see where the wires go. On the two I had on the Workhorse chassis the trailer plug was supplied and wired by Winnebago. On the exterior lighting installation diagram, it says "remove and reinstall after paint". The wiring was installed by Freightliner, but the taillights were done by Winnebago. Somewhere the wires are not connected and about all you can do is start testing starting at the back. Have they ever worked, or don't you know for sure? It's possible Winnebago cut into them for the rear lights if they never worked. Trace the wires from the taillights and see were theygo. Some of that stuff can get frustrating. Good Luck.

[LOG]

Update.
Freightliner finally, after a few phone calls, sent me the wiring diagram that shows the trailer wiring from the Turn Signal Switch to the Tow Harness PDM Module.
The wires for the 7 Pin Connector and the wires for the Coach Running Lights/Stop Lights and Turn lights are separate wires. There is one wire for the 7 pin connector Left Turn/Stop and one wire for the Right Turn/Stop Lights.
So, it most likely means it is either the Turn Signal Switch or the Brake light switch.
Mark (l1v3fr33ord1) told me, in a post some time ago, that that might be the problem.
I was not ready to change them until I found the Tow PDM Module to check the fuses. And, to obtain a wiring diagram to see if the Tow Wiring was separate from the Motohome.
I will update later.

[LOG]

I finally found the problem and it is repaired.
It turns out that it was a defective 7 Pin to 6 Pin wire harness.
The harness had checked Ok for continuity but would not pass thru 12 volt power.