Brake Controller Installation on a 2008 GMC Sierra and Chevy Silverado

Custom Fit Brake Controller

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When you install a brake controller on a 2008 GMC Sierra or Chevy Silverado, you will have additional wires under the hood which make the installation slightly different from a typical installation. The following will take you through step-by-step through this installation process.

Before installation begins, you will need 3 components:

1. Brake controller
2. Brake controller adapter - Draw-Tite 20127 , Valley V30520 or Tekonsha 7894
   • NOTE: Adapters are only required for brake controllers with a quick disconnect feature. Brake controllers with wires attached do not need an adapter.
3. 7-way replacement adapter (unless already installed from the factory)

Installing the 7-Way Replacement Socket (PK11916)

If your vehicle already has a 7-way trailer connector, skip ahead to "Connecting the Brake Controller Adapter (20127) to the Factory-Installed Tow Package"

1. Begin at the rear of the vehicle, behind the bumper. Unplug the round 7-pole factory-installed plug that leads to the outside of the bumper.

2. Move around to the outside of the bumper. Remove the square knockout panel, located to the left of the license plate.

3. With the square knockout panel removed, slide the 7-way replacement socket (PK11916) into the knockout hole. Line up the notches on the replacement socket with the notches in the knockout hole. Then rotate the replacement socket clockwise, locking it in place.

4. Return to the area behind the bumper. Insert the round 7-pole factory-installed plug (removed in step 1) into the 7-way replacement socket (installed in step 3).

NOTE: It's always a good idea to use dielectric grease to help seal electrical connections. Water intrusion of the 7-way connector can cause shorts and corrosion in the wiring. In particular, shorting of the brake controller blue power wire may set off warning codes in the brake controller. Dielectric grease will keep moisture from compromising these connections.

Connecting the Brake Controller Adapter (20127) to the Factory-Installed Tow Package

For brake controllers without the quick disconnect feature, no adapter is necessary. If your brake controller has wires already attached to the back, skip ahead to "Mounting the Brake Controller (Draw-Tite Activator III - 5520)"

1. Below the steering column, there is a bundle of wires tied together with white tape, located left of the brake pedal. This bundle of wires is the tow package for the brake controller. Carefully cut the white tape binding the wires, and pull the wires down from underneath the steering column.

2. Connect the four wires on the brake controller adapter (20127) to the tow package wires. Follow the table below to connect the tow package wires and adapter wires using butt connectors.

NOTE: DO NOT connect the tow package orange wire to any adapter wire. Use of the orange wire may result in inadequate, pulsating and/or no braking. Simply tie up the orange wire with any other unused tow package wires.

Tow Package	Brake Controller Adapter
Red	Black
Dark Blue	Blue
Light Blue	Red
White	White

3. Using electrical tape, bind the wires together.

Mounting the Brake Controller (Draw-Tite Activator III - 5520)

1. Choose an appropriate mounting location for the brake controller mounting bracket. A typical location is the lower right side of the dash, which allows easy access to the brake controller in the event of an emergency braking.

2. Using the screws provided, mount the mounting bracket into the dash. Make sure to avoid drilling through various components on the other side of the dash.

3. Using the screws provided, secure the brake controller into the mounting bracket.

4. Plug the adapter (20127) into the back of the brake controller (5520).

5. With the brake controller mounted and connected, zip tie any loose, excess wires underneath the dash. Do not allow the wires to interfere with the brake and gas pedals, and keep them away from areas of excessive heat.

Finalizing Connections for the Brake Controller

1. Under the hood, remove the cover for the power distribution box, located on the driver's side.

2. The ring terminal for brake controller power is located directly to the right of the power distribution box. It is taped to a wire harness between the driver-side front fender and the power distribution box. Cut the tape to release it from the harness. Then run the wire to the front of the power distribution box and hook the ring on the left post (M6 stud).

3. The ring terminal for the 12-volt power lead for the 7-way trailer connector is located to the left of the power distribution box. It is taped to a wire harness under the power brake booster. Cut the tape to release it from the harness. Then run the wire to the front of the power distribution box and hook the ring on the right post (M8 stud).

4. Tighten the ring terminals onto the posts using nuts (not provided).

5. Activate the brake controller power post by inserting an automotive style 30-amp fuse into the correct slot in the power distribution box.

6. Activate the 12-volt power lead post by inserting an automotive style 40-amp fuse into the correct slot in the power distribution box.

NOTE: Most vehicles are already equipped with the fuses listed in steps 5 and 6. However, if your vehicle does not have one or both fuses, you will need to insert your own fuses.

7. Place the cover back onto the power distribution box, and close the hood.