Brake Controller Installation: Starting from Scratch

Custom Fit Brake Controller

Before Installation You Will Need:

  1. Brake Controller
  2. 7-Way Installation Kit (#ETBC7)
  3. 4-Pole Trailer Connector (if not already installed)

Information About 7-Way and 6-Way Installation Kits

The 7-way Trailer Connector Has a Total of Seven Wires:

The Colors of the Remaining Four Wires:

The ETBC7 and ETBC6 Installation Kits:

All the parts necessary to connect a brake controller to your vehicle are included

The 7-way installation kit pictured with all included parts

The 7-Way Installation Kit Parts

  1. 7-way trailer connector, which includes a 4-pole adapter
  2. The mounting bracket secures to the vehicle's bumper or other appropriate mounting location and harbors the trailer connector.
    • Mounting hardware, such as self-tapping screws, is included to mount the bracket to the vehicle and the trailer connector to the bracket.
  3. The gray duplex cable houses two wires that will become the 12 volt hot lead and brake wire.
    • The duplex cable runs from the trailer connector to the front of the vehicle.
  4. The black loom is a hard plastic tube that covers the 12 volt hot lead and brake wire connections at the trailer connector, protecting the connections and giving your installation a professional appearance.
  5. Circuit breakers act as midway connections for the 12 volt hot lead and the brake controller power supply (introduced later) before they reach the vehicle's battery.
  6. Butt connectors help to make connections between wires.
  7. Ring terminals attach to the end of wires and hook around battery posts and circuit breakers.
  8. Zip ties help to bind loose wires together and prevent them from interfering with vehicle components such as brake and gas pedals.

Brake Controller Installations Steps

The duplex cable has been run towards the firewall at the front of the vehicle.

Installing and Wiring the 7-Way Trailer Connector

  1. Find a suitable location to mount the 7-way connector.
    • A typical location is on the bottom of the bumper.
    • Using the self-tapping screws, secure the mounting bracket into the bumper and the trailer connector into the bracket.
  2. Plug the 4-pole adapter coming out of the 7-way connector into the vehicle's 4-pole trailer connector.
  3. Ground the 7-way connector by screwing the white wire into the frame of the vehicle.
  4. Make a small cut in the rubber sheath of the duplex cable and slightly separate the two wires inside.
    • Use a butt connector to connect the black wire in the duplex cable to the 12 volt hot lead (black wire on the 7-way connector).
    • Then do the same for the white wire in the duplex cable and the brake wire (blue wire on the 7-way connector).
    • Next, route the duplex cable under the vehicle all the way up to the engine compartment under the hood, being careful to avoid hot areas or those that may pinch the cable.
    • Before you proceed further, the brake controller needs to be mounted.
      • We will return to the duplex cable shortly.

Brake controller sitting flush on the lower right side of the dash

Mounting the Brake Controller

  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 situation.
  2. Using the screws provided, install the mounting bracket into the dash.
    • Make sure you avoid drilling through components on the other side of the dash.
  3. Secure the brake controller into the mounting bracket.
  4. The four wires on the brake controller will be connected shortly.

The 12 volt hot lead and trailer feed have been separated before running through the firewall.

Wiring the 7-Way Trailer Connector and Brake Controller

1. Return to the duplex cable under the hood, where the brake wire (now white) needs to be separated from the 12 volt hot lead (black).

Circuit breakers mounted in the engine compartment

2. Using a butt connector, connect the blue wire coming out of the brake controller to the brake wire (white wire of the duplex cable) that was routed through the firewall.

3. Find a safe location under the hood or on the firewall to mount two circuit breakers: one 20-amp (or 30-amp; see brake controller instructions) and one 40-amp.

4. The black wire coming out of the brake controller is the brake controller power supply.

View of wires attached to positive and negative posts on battery

Brake switch wires located above the brake pedal

5. The white wire coming out of the brake controller is the ground wire.

6. Inside the cab, we only have one connection remaining.

7. With the brake controller mounted and connected, zip tie any loose, excess wires underneath the dash and under the vehicle.

brake control wiring diagram

Questions and Comments about this article

Dave Lambert 01/28/2020

Thanks for the helpful article. Questions:1. The brake controller is wired directly to the battery in the diagram. I could postulate safety reasons for this i.e. not to lose brakes if the engine quits or needed to apply brakes with the truck off but Is it acceptable to wire to an accessory with appropriate relay switch position. Seems like you would have a good potential to drain the battery if you left the controller on with the vehicle off.2. You used circuit breakers in this application. Is there a reason that circuit breakers were used in lieu of cheaper / simpler fuses. Again I could postulate that maybe you would hope that the breaker would reset if the fault cleared and still retain brakes.....? But you would still lose the brakes for some period of time whether the breaker tripped or the fuse blew...….64941

Reply from Jacob H 02/04/2020

If the break controller is operating properly, it would take a very long time for it to have any affect on the battery. Using a breaker is so that instead of having to replace the fuse when ever it blows, the breaker will trip and reset. You shouldn't have any issues with fuses or breakers if everything is wired correctly. If the breaker is not resetting then it will need to be replaced just like a blown fuse. 55387

Trent 01/30/2020

Which color wire on my break pedal wires is the power to the brake. 2003 gmc Sonoma ext 3 door no tow package.65059

Reply from Jason S 02/03/2020

I tried looking up your particular model for color. The closest vehicle I could find the color diagram for which I believe has the same wiring harness is the Chevy S10. On that model the wire color you'd be looking for is white. To confirm this or to diagnose your vehicle's brake wire, you will want to use a circuit tester like # PTW2992 to test the wire for power. You should only see power when the brake pedal is pressed and no power on the wire when the brake pedal is not.55244

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