How to Hook Up 3rd Brake Lamp on Aftermarket Roll Bar

Updated 06/25/2021 | Published 06/24/2021

Question:

I installed a roll bar in my bed of my 2020 Silverado. The bar blocks the factory third brake light, so the manufacturer installed a third brake light in the bar. Came with wiring, but I cant find where it hooks up. Could someone please tell me? Thank You

asked by: Herbert D

Expert Reply:

A company that installs truck bed camper shells would know more about this, but I'd be happy to provide what help I can.

A T-Connector like # C55384 wouldn't work because the brake lamp signal is carried on the same circuit as the turn signals which would cause the 3rd brake lamp to blink with the turn signal. You'll have better luck finding the circuit that feeds the CHMSL or 3rd brake lamp.

The easiest way to do this is to gently remove the existing 3rd brake lamp and use a circuit tester like # 40376 and test the wires until you find the wire that only shows voltage when the brake pedal is pressed. You'll probably need a helper for this. Once you locate the correct wire, tap the wire for the roll bar 3rd brake lamp into it. You'll need to find a grommet under the carpet that would allow you to pass the wire out of the cab and up to the roll bar.

expert reply by: Mike L