What To Do With Extra Green Illumination Wire On Toyota Brake Controller Wring Harness

Updated 07/17/2020 | Published 09/28/2011

Products Featured in This Question

Tekonsha Prodigy P2 Trailer Brake Controller - 1 to 4 Axles - Proportional

(2763)

$159.00

Hook Probe Circuit Tester

(60)

$12.27

Question:

per your color guide chart, my toyota wiring harness has an extra green wire, that you say is for illumination. what do I do with it?

asked by: Martin R

Expert Reply:

On a Toyota, the green wire you describe is for an illumination circuit and is not needed. You can confirm this if you wish by using a circuit tester like the part # PTW2993, on the green wire. This wire should only show voltage when the vehicle headlights are switched on. This wire can be taped up and stowed out of the way.

The wire colors on a Toyota factory brake controller harness are usually the black (12v power), the red (trailer brakes), the white with black tracer (ground) and the green with yellow tracer (stoplight).

The brake controller wiring connections should be like this.

The black wire on the factory harness goes to the black wire on the brake controller.
The red wire on the factory harness goes to the blue on the brake controller.
The white with black tracer wire goes to the white wire on the brake controller.
The green with yellow tracer wire goes to the red wire on the brake controller.

Vehicle manufacturers change wiring configurations regularly, so use the circuit tester to verify all connections.

I am including a link to a FAQ page on brake controllers that features additional information that you might find helpful.

expert reply by: Jeff D

George A.

7/12/2020

That green wrote is forthe traler lights. They don't work without it only brake lights work when hooked up this way. So where does the green wire need to go?

Chris R.

7/17/2020

The trailer light circuit shouldn't go through the brake controller wiring at all, so it wouldn't be connected in this application. Just to be clear, you are referring to the factory wiring beneath the dash?