Brake Controller Installation on a 2002 GMC Sierra Pickup, Possible Wire Colors and Functions

Updated 06/22/2010 | Published 06/19/2010

Products Featured in This Question

Tekonsha Voyager Trailer Brake Controller - 1 to 4 Axles - Proportional

(756)

$78.01

Hook Probe Circuit Tester

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$13.68

Question:

i have a2002 gmc truck it has a fractory plug in pig tail to wire up the voyhger brake controil could you tell me which wire hook up to what[ brake co,dark blue,white,red,black ,pig tail dark blue,red, lt.blue,black,br,] thanks

asked by: david g

Expert Reply:

You might have a port on your truck, driver side, to the left of the emergency brake pedal in a power distribution box. If so, you can just plug in wiring adapter # 3025-S and match the colors on the other end to the brake controller. To complete installation and to activate the tow package (if it has not been done already) there are some connections that need to be made under the hood. I have included an FAQ explaining the process below.

Wire colors are not an exact science, even on vehicles by the same manufacturer. The best way to find the functions of the wires is to use a circuit tester like # PTW2993.

Using the circuit tester, probe the wires on the truck until you find the one that carries a constant signal. This wire attaches to the black wire on the brake controller. It might be the red wire.

Next, find the wire on the truck that carries a signal ONLY when the brake pedal is pressed. Connect this wire to the red wire on the brake controller. It might be the light blue wire.

Next, take the 12-volt power wire you found in the first step and touch it to the dark blue wire on the harness. Test the trailer connector at the back of the vehicle for the 12-volt signal on the electric brake output pin on the 7-Way. If facing the plug, it is the bottom right blade. If you do not get a signal, try the process again with the brown wire on the truck. But first check to see if the brown wire has any signal with the key on and/or the vehicle lights on. If it does have a signal at any time, it is not the wire you are looking for and you should not try to run power through it. When you find the correct wire, attach it to the blue wire on the brake controller.

Last is the ground wire. This is most likely the black wire on the truck harness. It will attach to the white wire on the brake controller. The remaining wire on the truck harness is not used.

I have included an FAQ article on brake controller installation on 1999-2006 GMC trucks that should help below.