Ways to Find Stop Light Circuit on Truck for Brake Controller Install

Question:

hi i have a trailer with electric brakes that works well when towed with our pick up trucks and now we want to wire our semi truck with air brakes to tow the same trailer we understand that the brake lihgt are tied into the signals and need to install diode but we are not sure where the diodes need to be placed

asked by: Doug

Expert Reply:

Sounds like you are looking for a way to isolate the stoplight circuit for the installation of a brake controller in your semi-truck. The part # 118158 that you referenced would isolate the brake signal.

Or if there is wiring at the stoplight switch on the brake pedal of the truck you can test the wires that lead to it with a circuit tester like part # PTW2993 to find the circuit that only sees voltage when the brakes are applied.

I attached a help article on installing brake controllers for you to check out as well

expert reply by: Jameson C