Trailer Brake Lights Not Working After Installing Trailer Wiring Harness on a 1998 Chevy Astro  

Question:

Expert Reply:

It is possible that the taillight wiring on your 1998 Chevy Astro has more than one wire that carries the turn signal functions. If so, and you connected the wiring harness # HM41225 to those, then the brake light signal would not get to the 4-Way. You can double check the factory wires using a circuit tester such as # PTW2993 or a meter if you have one. Have someone sit in the vehicle and operate the brakes while you test the wires.

If everything is wired up correctly on the vehicle side AND the vehicle brake lights and turn signals are working, then the issue is on the trailer side, possibly a bad ground or a short. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light but can show up any time.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.

The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.

expert reply by: Michael H

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