Recommended Brake Controller And Wiring For 2004 Chevrolet Blazer

Question:

I have a 2004 Chevy Blazer 4 door 4 wheel drive with what I assume is a factor trailer wiring harness. It has a blue, light green, white, dark green, yellow, and brown wire. I am wanting to wire a 4 way with white, brown, yellow, and dark green wires, and a 7 way with a purple, white, dark green, and yellow wires together to the factory trailer wiring harness, so I can use either harness at one time. How should I wire these together in order to have a working 4 way plug and 7 way plug? I am working on a trailer and would like to have right turn, left turn, back-up, running, and license plate lights. Also I am considering adding a electronic brake controller system, what things would I need to add that to the my vehicle?

asked by: Matthew N

Expert Reply:

The brake controller I recommend is the P3, part # 90195. This is a proportional brake controller that applies the brakes with the same intensity as the brakes on the vehicle.

It sounds like you have a 7-way trailer connector already installed. You will need to look at the back of the 7-way you said you have on your Blazer. If it has an adapter that looks like the photo I have attached then you can simply unplug the 7-way on your Blazer and use part # HM40975. The # HM40975 has a 4-way and 7-way connector.

If you do not have a connector like the attached photo, and your 7-way is hardwired, you will need to cut the wires at the back of your 7-way and splice in a harness like part # PK11998, and then use # HM40975. Use a circuit tester like part # PTW2993 to identify the wires by function at the back of your existing 7-way.

You can use a circuit tester like part # 3808 to identify each of the wires by function. You can have someone sit in the driver seat and run through the functions while you test the wires. I have attached a drawing that shows how wiring is run for a brake controller you can check out. You will also need to make sure you have a 40-amp circuit breaker like part # PK54540 inline with the Black power wire from the trailer connector to the positive battery. You will also need a 30-amp circuit breaker like part # PK54530 installed inline on the Black wire from the brake controller to the positive battery post.