-Howdy Folks-
Wondering if anyone can help me out. Looking for a website/ video that goes over how to wire in a 3rd brake light on a aftermarket cap.
Does anyone knows which wires can be tapped coming out of the tail light... I believe top and bottom lights/ wires are breaks, so I'd assume there...? Just hoping for a confirmation before tapping and potentially causing a problem.

Thank you

Driving a 2022+ Silverado LT Trail Boss.

 

If you have the trailering system, I found this online:

I can confirm that the CHMSL wire is Brown/Yellow. It runs from the BCM to the pass side under the glovebox and up the pass side pillar if anyone is looking for it! Thanks again for the schematic-it narrowed down the wire colors!

I think the third brake light wire would be in the connectors referenced in this install:
https://boostautoparts.com/blogs/che...2022-gm-trucks

Center High Mounted Stop Light is how you find information on this stuff. Took me a while when I was researching to figure that out. I know on my old F150 this was a pain in the neck with the built in trailer system. You didn't want to connect anywhere in the back on those or you would have issues with the vehicle thinking it had a trailer connected or strange things happening in the lighting system so it was recommended to tap into the center high mounted third brake light wire on my prior vehicle.

Tapping into the 3rd tail light wiring is what I had to do on that vehicle and from the article above it kind of sounds like this is the best practice on the GM vehicles. I also found this harness on Amazon:
In the questions I see people with 2022 vehicles say this works.

I would contact Putco though and there may be other options as well. It would be pretty easy to find the wire under the dash using a test probe, run a wire out to your third tail light and see if it works. My truck cap third tail light was an LED and the lights on the F150 were LED as well.

 

I'm having the same problem with my truck cap, and I have same make/model but year older. Just wanted to see if you found a solution or the wires needed. Thanks