How to Test Wires of 2010 Ram 2500 to Hardwire Brake Controller

Question:

I am trying to add a brake controller to my truck and I have the universal wiring harness no one in town has the right plug and play adapter. Not a problem because I can just cut into the harness but I am not sure which wire goes where. The four wires in the factory harness are white with purple strip, black with blue strip and the other two thicker wires are yellow with red strip and solid green.

asked by: Rob

Expert Reply:

I can describe to you how to test each of your wires so that you can wire you brake controller to your 2010 Ram 2500, but I do not have the wire color information you are looking for.

You will need a circuit tester like part # PTW2993 to test the wires. The wire that has voltage all the time is the 12 volt power circuit and the black wire of the controller would get run to it. The wire that sees 12 volts when the brakes are applied is the stoplight circuit and is what the red wire of the controller gets run to.

Ground the tester to the constant 12-volt power wire, then probe the remaining two wires. The wire that lights the tester will be the ground (white) , the other will be the brake output circuit (blue).

expert reply by: Jameson C