Weak Trailer Brakes on 5th Wheel Trailer Towed by 2008 Chevy Silverado with Factory Brake Controller  

Question:

Expert Reply:

The problem could be the trailer brakes but it could also be the factory brake controller on your 2008 Chevy Silverado. Factory brake controllers are notorious for not working as well as aftermarket controllers and that could be the issue.

If you want you can test the brake magnets by following the help article I have linked for you. You can also check to make sure the self adjusting brakes are self-adjusting. When you spin a wheel you should hear a slight but constant dragging of the pad material on the drum. If you don't hear that then either the brakes are not adjusting out or the shoes need to be replaced because they have worn down enough.

If you want to install an aftermarket controller I recommend the P2 # 90885. To install it you will bypass the factory controller by using the tow package wire bundle under the dash, to the left of the steering column, held together with a white tag.

These wires are located above your left shin as you are seated in the driver's seat. The wires can be identified by a white label and the color of the wires. The wire colors are (1) Red/Black wire, (1) White wire, (1) Light Blue/White wire and (1) Dark Blue wire, and possibly (1) Orange wire.

Connect the brake control to these wires as follows:
GM Wire to Brake Control Wire Function
Red/Black to Black Battery Power
White to White Ground
Light Blue/White to Red Brake Light Signal
Dark Blue N/A Brake Control Output to Trailer
Orange N/A Center High Mount Stop Lamp (CHMSL)

Using enough 12-gauge wire to reach the rear of the truck, such as # 12-1-1 sold by the foot, connect one end to the Blue wire on the aftermarket brake control. I recommend at least 25 feet of wire. Run the other end of the wire in conduit or loom to the 7-way trailer connector. At the 7-way trailer connector you will have to remove some tape and pull back the plastic loom to access the factory-installed Blue wire. Cut the factory Blue wire approximately 4 to 6 inches from the trailer connector.

Connect remaining end of wire from aftermarket brake control to the Blue wire going to the trailer connector. After connection is made, heat shrink, reinstall plastic loom and re-tape loom.

To complete the installation, two wires under the hood have to be connected. One is the power supply wire to the aftermarket brake control. The other is the battery charge line to the 7-way connector. These wires are both Red/Black with eyelets connected to them. They are coiled up under the hood and must be connected to the under-hood fuse box. The brake control power wire is located between the fuse box and the left (driver's side) fender. The battery charge wire is located under the master cylinder/brake booster assembly.

The battery charge wire will go on the smaller Black stud, and an M6X1.0 metric nut is required to attach the wire to the stud. Larger posts require an M8 nut. The brake control wire will go on the larger Silver stud along with the existing Red wire. The existing Red wire is the power wire for the factory brake control and does not need to be removed.

Important: Raising the Gray handle above the studs more than 3/8 of an inch will result in the fuse box becoming disconnected from the electrical connector. If disconnection occurs, you may have to consult your local GM dealership for repairs.

expert reply by: Michael H

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