Back Up Lights not working

[emann_01]

thread title explains itself but here is the troubleshooting I have done...

- If I send +12V from the light side of the fuse, the lights come on...this proves wiring from fuse box to lights are good and bulbs are ok

- Fuse is fine...self explanatory

- when shifted to reverse, +12V does not come to the signal "side" of the fuse

- back up sensors still work when shifted to reverse so the I assume the switch in the column is still working

I think there is a BCM (body control module?) that is somewhere in this circuit. Where is it and how can I check it? Maybe a relay somewhere that I can check? If so, where?

Any help I can get with this I really really really appreciate!

Thanks in advance!

Eric

 

[emann_01]

a little help......anyone?

 

[08grey]

Check if there is signal at the trailer connection in the back. If there is take it from there for a simple fix.

 

[emann_01]

no signal at the trailer hookup. apparently the trailer signals piggy back off the vehicles signals?

Also, just found out that the trailer brake controller wires are not working (I did find the wires under in the engine back and bolted them down on the post) and now the rear licesnse plate lights are not working??

any help...anyone please???

 

[08grey]

Pins get corroded and break in the plug. Remove the plugs from the rear junction box and inspect.

 

[felixgun]

I had this issue with my avalanche but it was bc of an HID kit I put in. The control module was burnt out due to a fault of my own by splicing in a 35W ballast for an HID kit into my reverse lights. According to the shop it was at, the original incandescent bulb draws 7-8 amps whereas my HID kit was drawing ~40 amps. The setup worked great and I saw no issues from when I installed it in mid-2011 to mid-2014... until it burnt out. This is all what the body shop said. I had 7k worth of repairs on the vehicle from hitting a deer (or actually the deer hitting me) coincidentally around the same time and had other issues with the vehicle which made me just get rid of the vehicle all together. The body shop said I could've replaced the control module and all the wiring leading up to the reverse lights to fix the issue, but it was all speculation as it was never done.

 

[joshcarl]

Here's the schematic for the backup lamps circuit for a 2007 Yukon (you didn't specify the Y/M/M). i hope this helps!

 

[emann_01]

I had this issue with my avalanche but it was bc of an HID kit I put in. The control module was burnt out due to a fault of my own by splicing in a 35W ballast for an HID kit into my reverse lights. According to the shop it was at, the original incandescent bulb draws 7-8 amps whereas my HID kit was drawing ~40 amps. The setup worked great and I saw no issues from when I installed it in mid-2011 to mid-2014... until it burnt out. This is all what the body shop said. I had 7k worth of repairs on the vehicle from hitting a deer (or actually the deer hitting me) coincidentally around the same time and had other issues with the vehicle which made me just get rid of the vehicle all together. The body shop said I could've replaced the control module and all the wiring leading up to the reverse lights to fix the issue, but it was all speculation as it was never done.

Any idea where this control module is located?

 

[joshcarl]

i'm betting that it's the backup lamps relay in the underhood fuse box.

 

[felixgun]

Any idea where this control module is located?

I'm referring to the BCM. They recommended I get a new BCM and get it re-flashed at the dealer and all new wiring. Which is quite expensive after parts/labor. I didn't want to do all that and STILL have the issue, and since I had other electrical issues aside from the reverse lights, I said **** it and got a new vehicle instead.

 

[emann_01]

i'm betting that it's the backup lamps relay in the underhood fuse box.

Yeah I think this might have something to do with with but unfortunately I dont think its a replacable relay...is this right? I will have to replace the entire underhood circuit board?

Also, could any of this be causing the issues with the license plate lights and the trailer brake wires?

 

[joshcarl]

i found this thread: http://www.gmtruckclub.com/forum/threads/reverse-lights-on-constantly.130727/

it looks like you might need to replace the whole fuse box. maybe you can find someone local that will let you swap them out to test the theory.

 

[emann_01]

i found this thread: http://www.gmtruckclub.com/forum/threads/reverse-lights-on-constantly.130727/

it looks like you might need to replace the whole fuse box. maybe you can find someone local that will let you swap them out to test the theory.

Yeah, I read that exact same thread and thats what led me to think I need the entire cicuit board....

I went ahead and purchased one from gmpartsdirect...should be here Friday. Hopefully this fixes the issues!

I will give an update once I swap them out.

 

[emann_01]

So I swapped out the whole fuse box and problem solved! Reverse lights are working and trailer brake controller is hooked up and functioning.

I still have to get the license plate lamps to work but I think that is a bulb issue.

 

[joshcarl]

good to hear. post up if you need another schematic.

 

[Shimmy23]

To clarify, you replace the fuse box?

GM 19210438

 

[zimcocomp]

i'm betting that it's the backup lamps relay in the underhood fuse box.

I HAVE A SIMILAR PROBLEM ON MY 2013 TAHOE ssv, But where is that relay? I looked in the fuse box and found relating fuses, but not a relay relating to backup lights.

 

[Fless]

I HAVE A SIMILAR PROBLEM ON MY 2013 TAHOE ssv, But where is that relay? I looked in the fuse box and found relating fuses, but not a relay relating to backup lights.

The member you quoted hasn't been on here since 2017, so I wouldn't expect an answer from that party.

You might want to post in a new thread.

 

[petethepug]

I did a quick breeze of all the posts. Do we know what model year truck this is?

Are you running any LED bulbs in the truck?