Running Light Fuse Blowing

[TXMAX]

I bought a used 02 2500 HD and went to tow with it the first time and the running lights wouldn't come on. FInally, realized the fuse was blown. Replaced the fuse and it blew again. The truck has a Tekonsha (sp?) brake controler in it. Any idea what might be causing the fuse to blow besides just being grounded out? I never had this problem in my other '02 so I'm at a loss.

Thanks,

TXMAX

[seabee14]

Your running lights are not in the same circuits as the brake controller is. I would look at the 7-way connectors between TV and trailer or at the running light circuit on the trailer, maybe a clearance light or taillight wire is shorted to ground somewhere on the trailer. A volt/ohm meter is very useful for trouble shooting this kind of problem.
Good luck
Larry

[TXMAX]

Thanks. I know the trailer running lights are not on the same circuit as the truck's running lights (separately fused) but I had not heard that the brake lights and turn signal were not connected too.

[DmaxMaverick]

Originally posted by TXMAX:
Thanks. I know the trailer running lights are not on the same circuit as the truck's running lights (separately fused) but I had not heard that the brake lights and turn signal were not connected too. If your tow vehicle has amber signals (like the 2002 does), you have a relay that consolidates the signals into the brake circuit for the trailer. This is included in the trailering circuit in the truck.

The fuse for the truck's lights are in the cab. Fuses for the trailer wiring is under the hood. If you are continually blowing the fuse with the trailer hooked up, look to the trailer for problems. Some are grounded through the connector, some are not. It depends on how "custom" the trailer wiring is.

I have a friend (kinda' hard headed) that has 2 tow vehicles and 4 trailers of various types. One trailer he has had longer than all others, and the trucks. This trailer was wired to a previous truck, that he did himself, without a clue about standard wiring practices. Well, instead of correcting the original trailer wiring, he "adapted" each vehicle and trailer, as he aquired them, to match up with his old trailer. His reasoning is, "I know that one is right". He can't hook up and go anywhere without messing with trailer wires/lights/brakes for at least an hour.

At any rate, if you need to confirm your wiring circuit, there is a drawing of the plug in my sig. pic's with the poles labeled. Just click on the link in my sig. and select "Trailer Wiring".

[GMC-YA]

check around some of your local parts stores. I picked up a very handy tool for locating shorts to ground (or open). It consites of a small cylinder about the size of a d cell battry with 2 wires comeing out of it. You hook that up in place of the fuze and use a meter (supplied in the kit) and move it near the wires, when the needle jumps you found the problem. Iv'e even seen some of these that buzz or beep. price I think was about $20. It's the kind of thing that sits in my tool box takeing up space but when you need it your glad ya gotit!!

[TXMAX]

Gents,

THanks for the replies. The fuse was blown when I got the truck (I found out when the trailer lights didn't work). I'm going to find one of those nifty little cheaters for finding shorts and get after it.

Thanks again.