Brake Controller Wiring Functions and Where They Need to Install

Question:

Hi I do not have a factory harness and must wire using the pigtail. I read the Tekonsha P3 manual you provided the link to. It states: Option 1: Use Pigtail Wiring Harness included. This harness can be installed by following the Generic Wiring Guide. But the Generic Wiring Guide is not a part of this manual. Do you have a link to it? I want to see where the 20A breaker you say is necessary for this type of installation fits into the picture.

asked by: Bob

Helpful Expert Reply:

The generic wiring guide in question just tells you the functions of the wires: white is ground, black is 12-volt power in (this is the wire that gets the circuit breaker), red is input from the brake switch, and blue is output to the trailer brakes.

The white ground wire needs to be attached to the negative battery terminal. No other location is sufficient enough. The black wire attaches to the positive battery terminal via the circuit breaker although I recommend a 30-amp breaker, # PK54530, instead of a 20 because you never know if you will tow a trailer with more brake assemblies in the future.

To find the right brake switch wire you will need a circuit tester such as # PTW2993. Test the brake switch wires until you find the one that only has power when the brake pedal is pressed. If it has power with the headlights or turn signals on then it is not the correct wire.

The blue wire is output to the trailer brakes and will go to the back of a 7-Way trailer connector in the 7 o'clock position.

If you can tell me what vehicle you have I can probably give you more specific details about the installation.

expert reply by: Michael H