Trailer Backup Lights (TRL B/U Fuse) No Power

[BigDogYJ]

Here's an interesting one...
I finally got around to adding reverse lights in my bumper and decided to wire them up and just use the Trailer Backup lights circuit to trigger my relay. So I get all the wiring in place soldered, heatshrinked, etc. I'm happy its all done, I go to test it and nada. checked for voltage at the relay, 12v battery good, ground good. No 12V from Trailer Reverse lights wire. no problem check fuse. Fuse is good. But there's no 12v power to the fuse slot at all (TRL B/U). Pulled up the fuse box, there's the light green wire coming from that slot going into the harness that runs under the truck but that fuse slot is just dead.

Did some quick searching online and a couple other folks experienced the same issue (no 12v power at the fuse box) but never had any resolution. Anyone else have issues with the trailer backup lights circuit? Can anyone check to see if their truck has power at that fuse? My wife 04 Yukon 1500 is 200 miles away otherwise I'd check it (but figured I'd ask). I ended up splicing into the actual truck reverse lights since those work fine, but just curious why I don't have power at that fuse, seems odd. I was looking through the wiring diagram and it seems it is controlled via the TRUCK B/U fuse as well as the NSBU switch on the trans. I didnt go down to the switch yet to check but I guess I can check that next.

Anyways just curious.

 

[MrMarty51]

Take a wire from one of the key on live circuits and run a wire from that circuit over to the dead BU lamp circuit , remove the dead wire and have a compatible end on the wire, plug it into the mr dead wire slot. Problem solved.

 

[Will L.]

I recall something about it getting hooked in when the buyer pays for “towing package option” like there was a wire we had to connect before delivery to the original purchaser. Been to long to remember details, but pretty sure it is just making a connection somewhere. We would do that, add the “Tee” harness at the rear to models that didn’t have it and bolt on a hitch kit.

 

[BigDogYJ]

Take a wire from one of the key on live circuits and run a wire from that circuit over to the dead BU lamp circuit , remove the dead wire and have a compatible end on the wire, plug it into the mr dead wire slot. Problem solved.

I tried that but still no dice. According to the wiring diagram it also goes through the NSBU switch. I never got under there to check it. Just t spliced into the regular backup lights and tied it to the trailer backup lights via a relay fed from the trailer aux power circuit (stud 2). Its working now but not how i hoped. When i have more time I’ll trace it back to the NSBU switch to see what i find.
Thanks for the input.

 

[BigDogYJ]

I recall something about it getting hooked in when the buyer pays for “towing package option” like there was a wire we had to connect before delivery to the original purchaser. Been to long to remember details, but pretty sure it is just making a connection somewhere. We would do that, add the “Tee” harness at the rear to models that didn’t have it and bolt on a hitch kit.

I do recall something like this but I’ve got a light green wire at the fuse box, and at the trailer harness at the back. . Figured that would be good. Oh well

I’ll check the wire from the both sides to the NSBU to see if anything comes of that. Probably won’t get to that now. Trying to tie up a few other projects before we head out for Tennessee.