Where is the brake wire located and what color is it for hooking up third brake light on truck cap . Can you tap into trailer hitch wires, if so, what color wire?

Thanks,
-Dan

 

Not sure but get a cheap test light and test the four wire trailer light plug for the right one.

 

There's a plug under the bed, near the spare tire that I think is for that purpose.

 

Trailer wiring (7-way) Red and brown are your left and right turn/stop signals. So if you use either of those your extra brake light will blink with whichever of the wires you use.

ARE makes truck caps with third brake lights, send them an email for instructions. I gave mine away with the truck when I sold it last month otherwise I would add it here.

If you don't have a third brake light feed to use you may need to add a relay.

I realize that this item below is not what you need, but there are similar items to accomplish your goal.

I am using this relay to "not" have my brake light activate directionals I am adding to the side of my 5th wheel.

2" Heavy Duty Relay Style 2 to 3 Tail Light Converter

2" Heavy Duty Relay Style 2 to 3 Tail Light Converter - eBay (item 180440046079 end time Dec-26-10 10:05:44 PST)

 

Earlier model trucks had a single blunt cut wire that came out of the main loom towards the rear. It was taped to the loom and had a bit of heat shrink on the end. It was usually labeled "CHMSL" or something similar. It was put there purposely for aftermarket third brake lights.

I'd be surprised if the newer trucks didn't have the same thing.

 

And CHMSL is the acronym for "center high mounted stop light"