How to Find Stop Light Switch Wire at Brake Pedal for Brake Controller on 2008 Dodge Ram 1500

Question:

How do you identify which of the 6 or 7 wires in the Brake Switch Harness is the one wire you need to tie into for the Brake Controller? The kit comes with a small circuit tester, but I am not sure how that will help since I can only access the harness by first unplugging it from the brake switch itself. Additionally, once wired in, is there a way to test the install without a trailer attached? If so, how? Not sure it matters but I am installing on a an 08 Dodge Ram 1500.

asked by: Scott

Expert Reply:

If you can become a contortionist, you'll be able to easily test the wires under the dash so you can find the one that is only active while the pedal is pressed. I have done this many times on several different vehicles. it's never once been easy. It just stinks, there's no way around this. There is one other trick though, a hook and loop circuit tester like the Hook Probe Circuit Tester part # PTW2993 makes it much easier. That said, I have some good resources at my disposal and from the best of my knowledge the wire that you need is white. This would then be attached to the red wire on a trailer brake controller like the Tekonsha Prodigy P3 Trailer Brake Controller part # 90195.

In regards to testing the controller, just probe the brake output pin inside the vehicle side connector with the pedal and override applied. That said, most controller are proportional so you really won't be able to see much voltage at the connector with the brake pedal.

expert reply by: Conner L