Installation of Brake Controller on 1990 Ford Bronco.  

You will have to hardwire your brake controller into the existing wiring of your Bronco. Your best bet would be to use our Brake Controller Installation Kit, part # ETBC7. The kit contains everything necessary for installing your brake controller, including the trailer connector, wire, and circuit breakers. The brake controller will have four wires exiting the rear. The black wire runs to the positive battery terminal, using the inline 20- or 30-amp circuit breaker included in the install kit. Your brake controller instructions will specify which breaker should be used. The white controller wire will attach to the negative battery terminal, and the red controller wire attaches to the brake stoplight switch located at the top of the brake pedal. You will want to use a circuit tester, like part # PTW2993 to test the wires exiting the stoplight switch. When you locate the wire that shows a signal only when the brake pedal is pressed, tap that red wire into that circuit. The blue brake output wire would run through the firewall, and then under the vehicle to the rear to attach to the 7-way connector. If you want to enable the 12-volt accessory power circuit on your trailer connector, you will need to run a wire from the trailer connector to the positive battery terminal via the 40-amp breaker included in the install kit. If your Bronco already has the 4-pole connector, it will plug directly into the adapter on the 7-way connector included in the install kit. If not, you can cut off the 4-pole on the adapter and wire it directly into the taillight circuits. The circuit tester I recommended above will come in handy here. Access the wiring behind the taillight assemblies, probe the wires as each lighting function is activated. Once the left turn circuit is activated, tap into that wire and attach to the appropriate pin on the 7-way. You will need to do the same for the right turn and running light circuit, as well. We have a Brake Controller Install Guide online that you might find helpful. I have included a link to this guide below.