How to Find Stoplight Circuit for Installing Brake Controller

Question:

I have an 2012 NPR Izuzu Installed brake controller but the brake pedal switch is hot until depressed. I am assuming it is working through the grounds. Where do I find the hot wire to activate the brake controller - Red wire on Drawtite

asked by: Neil D

Expert Reply:

You'll need to test the wires that lead to the stoplight switch till you find one that has voltage only when the brakes are applied. Beyond that we do not know which wire you need to use. The red wire of your controller is the correct wire to use once you find this circuit though.

For a circuit tester we have the part # 3808.

expert reply by: Jameson C