Installation of the Wiring Harness Brake Controller Functions on a 2003 Chevy Trailblazer

Question:

My 2003 Chevy Trailblazer has the tow package trailer brake harness. The light blue wire is connected to a brown with black stripe wire. Do I connect both wires to the red wire on the controller or should cut off the brown/black wire.

asked by: Les

Expert Reply:

First, I suggest you use a circuit tester kit such as #PTW2992 to confirm the function of each vehicle wire before connecting them to the pigtail leads for the brake controller.

Find the one wire that has 12V power all the time, one that has power only when you press the brake pedal, and two that carry no voltage when tested.

Remove the quick connector plug on the brake controller # HM47295 and splice the 4 wires to the function wires under the dash. The 4 wires on the brake controller are as follows:

White wire – ground
Blue wire – brake controller output to your trailer connector
Black wire – 12V power input to operate the controller
Red wire – brake signal input wire from brake light switch

If you don't have the factory 7-way, the wiring won't be there, and you will need to use the universal installation kit for trailer brake controller # ETBC7 and hardwire.

Use the circuit tester # PTW2992 to match up the vehicle wires by function to the appropriate wires on the controller's pigtail harness.

The vehicle wire with 12V power at all times connects to the controller black wire. The vehicle wire with power only when you press the brake goes to the red wire. White ground wires connect together. The vehicle wire that runs to the 7-Ways's pin at the 5-o-clock position connects to the controller's blue output wire. See photo to the right.

I have included a circuit tester video and installation instructions for you as well.