Hey eveyrone, I bought a used camper shell and wanted to wire up the 12v white and tan wire running underneath the truck (used for the third brake light) to the brake light assembly itself. Thing is, instead of a red/black wire coming from the light assembly, or even a solid white and one solid black set of wires, I have one solid black and one white/black wire. which one is the correct wire to attach it to? If anyone has wired this before, please let me know, i just dont want to damage the light assembly.

 

We need the year of your truck...

 

As long as it's not a led light you will do no damage hooking it up backwards. You can use a meter to figure out what is ground and witch is power. If you have the trailer package you can tap into the harness going to that also.