Brake Controller Recommendation and Installation on a 2003 GMC Sierra with or without Factory 7-Way


I have a 2003 GMC Sierra Pick-up and a 2005 RVison Trail Quest travel trailer. The trailer has Dexter Axles installed on it. Will this Dexter Brake controller work with my two axle travel trailer? The description doesnt say how many axles it will work with. Also, will I need any other wiring to hook it up? If it works together or does it come with everything ill need?


Expert Reply:

I did a little research and found that the Dexter Predator, # 58-8, is for 2 to 4 brakes. So if each wheel on your two axle trailer has a brake assembly, or just two of them, this brake controller will work.

Brake controllers are not vehicle or trailer specific, so you will be able to use the best one for your application. I recommend going with a proportional controller because they offer the best and safest braking, and will reduce wear on both the trailer and tow vehicle brakes. I have included a link to a brake controller FAQ page below.

For a proportional controller, I recommend the Tekonsha Prodigy P2, # 90885. It is the newest version of the popular and highly rated Prodigy series. It is easy to use and easy to mount. I have included a link to the installation details below.

As far as installation, there are two possible options. If your truck has a factory 7-Way trailer connector, you will just need part # 90885 and wiring adapter # 3015-P. One end of the wiring plugs into the back of the brake controller, the other end plugs into a port under the dash. The port is located to the left of the brake pedal. Remove the cover and plug in the wiring harness to the second port from the left on the top row. After mounting the brake controller installation will be complete.

If your truck does not have a factory 7-Way, You will still need # 90885 and wiring adapter # 3015-P, and install it as described above. But, there are a few more connections that need to be made to activate the brake controller and trailer wiring.

You would also need to add Replacement Multi-Tow 7-Way and 4-Way Trailer Connectors, # 30955. One end plugs into a port located above the spare tire and the other end mounts at the rear of the truck. I have included a video that shows this installation below.

Under the hood, there are a couple of connections that will need to be made. Locate the power distribution box on the driver side and remove both the lid and lower cover. You will find a blue and red wire near the back of the box. You will need to wire the red and blue wires so your brake controller will work.

First, place the red wire over the closest positive post (back left if facing the truck from the front) on the fuse block. A 20 or 30 amp fuse (see the brake controller instructions for which size to use) is needed in the empty slot nearest the positive post to power the brake controller.

Next, clip off the connector on the blue wire and connect it to a wire that you will need to run to the electric brake wire coming off the back side of your 7-Way plug in the rear of the truck (you would need to tap into the blue wire of the 7-Way you installed so instead of it being connected via the plug, it would be hardwired).

If you also need power run to the 7-Way connector, you can run a wire underneath the hood to the other auxiliary power post near the fuse block. You would then install a 40 amp fuse in the slot closest to this power post. I recommend using the jacketed 2 wire, # 10-2-1. You could use one of the wires for power to the 7-Way (hardwire into the black wire on the back of the 7-Way) and the other to route from the blue wire back to the 7-Way blue wire.

If the second auxiliary power post is already in use, you could also just run the power wire to the positive battery terminal and install a 40 amp circuit breaker, part # PK54540, if needed. If you used the white wire from the # 10-2-1 for your blue wire under the hood, you could use the black wire to run your power lead. I have included a link below that shows images and more instructions for wiring your Sierra.

expert reply by:
Michael H

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