Where to Connect the Brake Light Switch Wire on a 1986 Ford F-150 When Installing Brake Controller

Updated 05/02/2017 | Published 04/30/2017

Question:

First I understand all the wiring and where everything goes. A supplemental sheet was included with the controller. It states inch Ford added a wire on late model Trucks etc...starting in 1998 on some vehicle. The wire is red with a green stripe and is only hot when the brake pedal is depressed. When the brake pedal is not depressed this wire goes directly to ground. Additional instructions tell not to use this wire, it will destroy the unit. etc. when using the Manual Control....On 1998 thru 2005 model connect to the light green wire from the stoplight switch. I have a 1986 Ford F150 had to wire from scratch. All wiring is correct however when I check the brake light switch...hot wire in and when depressed pedal power going out the other wire only two wires. After reading the note I checked the circuit. Once released it goes to ground. Everything works correctly with the truck- turn, stop, park lamps. Where do I connect the red wire from the controller to ensure no damage occurs to the unit.

asked by: David

Expert Reply:

On a typical brake controller installation, you will connect the brake light switch red wire coming from the brake controller to the cold side of the brake light switch.

The wire will then get a signal when the brake pedal is being pressed to let the brake controller know when to apply trailer brakes. Using a circuit tester like # PTW2993 can help you find the correct wire at the brake light switch that needs to be tapped into when connecting to the brake controller.

The attached diagram will show the typical wiring for a brake controller being wired from scratch on your vehicle.

Being that your vehicle is a 1986 model F-150, you will not have any issue connecting the brake controller light switch wire from the brake controller to the stop light switch.

expert reply by: Jared P