Power to the Trailer

[richp]

Hi,

Background: Old truck, new trailer. Never once thought to check if I was getting 12 volt power to the old trailer from the truck, since I had two solar panels on the roof. I never thought once to check on whether the batteries from the truck were sending power to the trailer. The new trailer has no solar panels, so I'm going to need the truck batteries talking to the trailer battery.

Situation/Problem: There is no 12 volt power to the trailer from the 7-pin plug. A forty amp fuse is in the proper place in the fuse box, and it tests OK for continuity. There is a 12.65 volt reading at the stud where the red/black wire (with a tag for trailer power) is attached on the side of the fuse box. There is no power at the outer plug on the 12+ connector. There is no power on the inner connection when the plug assembly is pulled apart.

Question: Is there an in-line fuse somewhere that I get to and check, or is this more likely a broken wire somewhere in the harness between the stud and the plug at the rear?

Thanks for any help you can provide.

[tpitt]

Try taking apart the plug on the pick up. I've had problems with the connecter there.

[richp]

Hi tpitt,

Thanks for the idea. Unfortunately, I already did that. There is no current at the inner set of contacts either.

I even inserted a probe through the insulation of the wire feeding the inner contact, to see if it was a bad connection with the contact itself. There is no current in the wire an inch or so before it enters the housing where it joins the contacts inside the plastic housing.

I'm guessing a broken wire somewhere in the wiring harness. But I sure am hoping someone would tell me there is an in-line fuse I can replace, and how to get to it.

I just realized this probably should be in the Towing section. If a moderator wants to move it, or wants me to re-post there, that's fine with me.

[richp]

Hi,

Out of time considerations because of a pending trip, I took it to the dealer today. And the answer is there are two black/red wires available for connection to Stud #1 on my truck.

The connected wire I had been looking at evidently stubs out under the dash. It's intended to be used only if an aftermarket brake controller is installed, instead of the factory controller that's on my truck.

The one that was not hooked up is the one that carries the 12 volts to the trailer. Yes, it's now apparent that this is the wire that everyone says needs to be connected for trailer use. But looking at another identical black/red wire connected to Stud #1 threw me off.

I have a great GM service department (Bob Jass Chevrolet, Elburn, IL). The tech there figured all this out in short order, and fixed it at no charge.