trailer light issues

[ThaMule]

here is what we are working with. 2003 gmc crew cab 2500hd duramax.

Problem is that my trailer has running lights but no blinkers or brake lights. Bulbs are good and the wiring on the trailer is good. So what the hell is going on?

I think the flasher unit has something to do with it because the trailer uses dual filaments and the lights on the truck uses seperate bulbs and the flasher unit keeps them seperate so they dont glow all the time.

What do yall think?

 

[lectric80]

Was the wiring originally installed from the factory? If not it will require a little box that combines the brake and turn source into a single point. If this box isn't working, on a factory installed system, it will not send any brake or turn signal information to the trailer. Unfortunately, I don't know where it is installed, or if it is something that is easy to change on the factory wiring.

 

[ThaMule]

Its all factory wiring. I also just found out that the trailer has its on fuses inside the fuse panel on the truck. It never crossed my mind that the trailer would have its own fuses on the truck. Im gonna go check that out here pretty quick

 

[sweetk30]

yep all the newer rigs have tons of fuses. all else fails check for a fuse first.

let us know how you make out.

 

[ThaMule]

Hey guys. Turns out it was both the turn signal fuses! thank god it was an easy fix and not a wiring harness problem!!