H3 Trailer Light Woes

[5gn-h3t]

The trailer lights aren't working on my '08 Alpha. The trailer B+ fuse was blown. I replaced it and still have no power on the "Running Lights" position of the trailer plug.

Any ideas?

 

[f5moab]

I believe running lights are powered by Fuse 55 (10A). The B+ fuse supplies battery supply to the trailer. But, why are they blowing? Check the wiring back at the rear tire and rear bumper to make sure they have not been compromised. I know on 06 vehicles they had a problem with the trailer wiring harness coming into contact with the muffler and burning off insulation and shorting.

 

[5gn-h3t]

I checked fuse 55 and it was good. I bought the H3 in January and this is the first time I've attempted to connect a trailer. I assume this was an existing problem and did not occur when I connected the trailer. The replacement fuse did not blow. I have a small trailer and it does not use the B+ connection. I checked the harness but will give it a closer inspection tomorrow.

Thank you!

 

[f5moab]

 

[5gn-h3t]

Thanks for the wiring diagrams.

Fuse 55 has 14+ volts going to it and has not blown. The B+ fuse has not blown again. The harness looks pristine. :sigh:

Guess it's time to start digging.

 

[M22KLARS]

This is one of the many problems with my truck right now. Check your tail lights and make sure they are both working.

 

[5gn-h3t]

Tail lights on truck work fine.

Just read your thread. Let me know if you find anything. I'm going to dig deeper when I get the time.

 

[5gn-h3t]

I was under the truck looking for faults. I opened the rear gate and looked down. The problem became very obvious. The wires have rubbed through on the body seam.

Thanks to everyone for the help!

 

[Hummeron37s]

I know this is a older thread but I have been fighting the H3 with the trailer wiring for about a year. I finally dove in head first yesterday and spent about four hours trying to diagnose the problem. Today went out and again spent about four hours and reached up trying to get the harness down but couldn't. Went in for a quick break and read this and opened the rear door and BAM...brown wire was in half and red was barely holding on. Pulled the connector and soldered the wires, and put a tin if electrical tape to protect it. Finally I have running lights, taillights and the fuse don't blow..thanks

 

[3Hummers]

Hey HO37. Long time. Hope all is well with you and your family.

 

[alrock]

Cool, glad you got it solved. Brodie also mentioned he'd find corrosion in those wires by the rear bumper which would cause odd conditions.