How to Wire Up Electric Trailer Brakesby Contributor
Helpful information on how to wire up electric trailer brakes.
First, try your luck with any/all manuals for your vehicle and/or trailer. You should be able to find what you are looking for there. However, if you don't have the manuals, or that information isn't provided, then this information may help you. The color of the wires is what they will usually be, but occassionally the color scheme will be different.
TRAILER FEED (Blue wire) is the wire that allows power for the controller to the 6-way or 7-way trailer connector at the back of the vehicle. If you are lucky (and have the factory tow package already installed) you may already have this wire running from under the dash to the rear of the vehicle. If not, the wire needs to be run under the vehicle and through the firewall (to the Brake Control mounting location.) If there is not already pre-existing holes for such wires, then a hole must be drilled. Use a power drill and steel drill bits. Before drilling, make sure you know where the bit will end up once it's through the firewall. I usually make a small pilot hole and then increase the bit size until the hole is big enough for the wire. A stepped bit would be great to use. Protect the drilled hole edges from rust with paint or a similar material. Install a rubber grommet into the hole to protect the wire from chaffing (VERY IMPORTANT!) Caulk the gap between the inner diameter of the rubber grommet and the power wire if necessary to prevent water from running down the wire.
GROUND WIRE (white wire) This wire connects from the brake controller to any reliable ground location.
BRAKE SWITCH (red) This is usually found near the top of the brake pedal. There are wires extending from the switch and using a circuit tester, you can find the wire that has power when the brake pedal is pressed. You can find a decent circuit tester on Amazon.com for around $20, or just shop around for what you want. Tap the wire using a scotch lock (or scotchlok.) You can find the exact one that you need and information on how to use it at your local hardware store. It is fairly simple to use.
BATTERY POWER (black) This connection supllies power to the brake controller. Your factory tow package (if you have one) might already have this wire running from under the dash to the battery with some kind of circuit protection. If not, a wire must be run through the firewall and connected directly to the battery with an in line circuit breaker. In Step 2 there are instructions for drilling through the firewall.