Troubleshot down to not get a 12v pwr or running lights pwr at the plug on truck. Turn signals and brake lights work just fine.

I've checked both underhood fuses and side panel fuses and for the life of me can't find any blown fuses. Any other ideas?

Truck is a 2004, GMC Sierra.

Thanks guys

 

Check the TRL Park fuse in the underhood fuse block with a test light. Make sure both sides light with the parking lights on. If both sides light then your chasing a broken wire.

 

Am I correct in thinking that all trucks were assembled with a wiring harness that is meant for trailer lights? And for those trucks that didn't come with a tow package all you would need is a small harness that plugs into the brake light/license plate light sockets?

 

From what I was told at the stealership and from my looking under my own truck, there is a seperat harness that goes from the rear of the truck to the fuse box in the engine bay. And the price was like 250 for the harness and the trailer light plug.

 

Ouch...that doesn't sound promising. I know for other vehicles that aren't meant for towing (such as my diesel VW), when I added a hitch to it all I had to buy was a $20 harness that tapped into the brake lights...I might see if I can't get something similar. I'm not spending $250 for a stupid harness!

 

I just about fell over when I had asked about that harness one time for getting the plug on the hitch because it is suppose to be all one (just cant get the plug alone according to the parts guy). And Reese I believe sells a tap-in harness that uses the plug under the bed. But they usually only come in the four flat plug.