No reverse lights

cody_s

Original poster
Member
Dec 6, 2011
625
Atlanta, GA
So I have two auxiliary reverse lights on the back of my roof rack, as well as the factory reverse lights in the bumper. When I installed the aux lights, I wired in a switch so I could turn the reverse lights on as work lights when the truck wasn't in reverse. This setup has worked fine for quite sometime. However one of the wires on the back of the switch was apparently loose, and ended up touching the other connection on the switch, so that even when the switch was shut off, the reverse lights would stay on. I fixed this, and got the switch to function again, but now when I put the truck in reverse, the lights do not come on, only when I flip the switch. I thought maybe I blew the back up light fuse, so I replaced that (Fuse number 27 under the hood if I remember correctly), but they still aren't working. Any thoughts on what could be going on?

PS, I also noticed the little green indicators above the headlight and foglight switches don't turn on when the headlights and/or fogs are on. Not sure if this is related or not.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
I don't recall where you got the backup power signal from. If it was the trailer backup light connection, try underhood fuse #4.

I'm a business trip without my Helm manuals, but the PDFs from this site imply that TBC5 fuse is involved. Rear fuse #32. I think that's because the BCM has to be involved in the vehicle-mounted backup lights so they can be flashed for the security arming function.

The headlight switch indicators are run from the BCM, but I think they're on a dimmable lamp bus, which would imply TBC3 or TBC4 fuses (rear #4 and #40) are involved.
 

cody_s

Original poster
Member
Dec 6, 2011
625
Atlanta, GA
the roadie said:
I don't recall where you got the backup power signal from. If it was the trailer backup light connection, try underhood fuse #4.

I'm a business trip without my Helm manuals, but the PDFs from this site imply that TBC5 fuse is involved. Rear fuse #32. I think that's because the BCM has to be involved in the vehicle-mounted backup lights so they can be flashed for the security arming function.

The headlight switch indicators are run from the BCM, but I think they're on a dimmable lamp bus, which would imply TBC3 or TBC4 fuses (rear #4 and #40) are involved.

Thanks, looks like those TBC fuses solved the problem. And as far as where I got the signal from, I just connected them to the wire going to one of the factory reverse lights.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
You'll only blow the TBC fuse again. Looks like you can't add a lot of current load to the existing backup light circuit. So you'll have to add a relay to the circuit to get your aux light current from another fused source, but allow the existing backup light circuit to control the relay.
 

cody_s

Original poster
Member
Dec 6, 2011
625
Atlanta, GA
the roadie said:
You'll only blow the TBC fuse again. Looks like you can't add a lot of current load to the existing backup light circuit. So you'll have to add a relay to the circuit to get your aux light current from another fused source, but allow the existing backup light circuit to control the relay.

Hm, I was thinking the only reason it blew was because of a short when the two wires were touching behind the switch. They had been working for a few months before then, and the fuse didn't blow until after the wire touching incident. But running a relay probably is the best solution. I'll see what I can come up with. Thanks for the help, you're a light saver. (See what I did there?)
 

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