Connecting a Brake Controller to a 2012 Toyota Tundra Factory Wiring Harness with Green Wire

Updated 06/30/2014 | Published 06/27/2014

Question:

Wire harness included in glove box for 2012 Toyota tundra has 5 wires . Brake controller has 4 wires .what do I do with the green wire from the Toyota harness it has no wire to be connected to on the brake controller harness. Do I just wire nut it off?

asked by: Dave R

Expert Reply:

You have to be careful not to connect the Toyota harness to the brake controller color for color because there is no standard for wiring color and function.

On the brake controller, the white wire is ground, black is 12 volt power in, red is input from the brake switch, and blue is output to the trailer brakes.

Based on the information I have on the 2 possible Toyota harness configurations, the green wire is not used in either one. So you could just cap it off and stow it out of the way.

In the harness has a black wire with red tracer then the functions of the Toyota harness are: black with red is 12 volt power, green with white is input from brake light switch, brown is ground, red is output to trailer brakes.

If it has a flat black wire then the functions are black for 12 volt power, green with yellow for input from the brake switch, white with black for ground, red for output to trailer brakes.

expert reply by: Michael H