Trailer interior lights
I bought an enclosed car trailer a couple of years ago and the interior lights never worked. The previous owner said they didnít work for him and gave me wiring schematics. I didnít spend alot of time on it but last week I took the trailer for a professional service on axles and brakes; they fixed the problem in about 3 minutes.
The fellow raised the hood ON MY TRUCK and removed the fusebox cover on the driverís side. He then reached into the wire loom nearby and pulled out a length of red wire that had a connector on the end. That wire went on the middle post of the fuse box. He put a fuse in the circuit and VOILA... lights in the trailer.
I somehow overlooked that if it was in the ownerís manual.
My truck is a 2008 2500 HD w/ the towing package. I hope this helps someone.
Yep, the infamous "what's this red wire for" wire.
Also used to charge an on-board battery if one is installed.
Sometimes wrapped up in the Glove box too....
Usually they have to add a fuse, too...
Originally Posted by SurrealOne
On my 2012, there are three of those "red wires" and two fuses required...aftermarket brake controller wiring, trailer 12VDC power wiring, and roof-mounted beacon wiring...and then the fuses to power the two studs these get hooked to.
The 90's trucks have the fuses preinstalled... back when GM cared.