Brake Lights Not Working on Trailer Towed By 1996 Ford Aerostar

Question:

have a 4 wire harness on a 96 ford aerostar every light works but no brake lights at alll

asked by: Dave G

Expert Reply:

If you are using an aftermarket connecter, when the trailer connector was installed a tail light converter might not have been used. If this is the case, you will not be getting the signal for the brake lamps. This would explain the issue you are having. If this is an OEM trailer connector, typically the towing circuits are protected by fuses located in the engine compartment. Check the fuses and replace if needed.

Trailer tail lights have the brake lamp and the turn signal combined onto the same circuit. Your Aerostar uses separate circuits for the brake lamp and the turn signals. A tail light converter like part # 119178KIT will combine the brake lamp and directional signals onto one circuit, so the wiring will be compatible with the trailer.

The inputs on the converter will need to be hardwired. The yellow wire will tap into the left turn circuit, the green wire into the right turn, the brown wire into the running light circuit and the red wire into the brake light circuit. The circuit tester included with the converter will be helpful in determining which wire controls which function.

I have linked to the install instructions for the converter, as well as a video that will show how to use the tester if you are not familiar with the process.

expert reply by: Mike L