Trailer Lights Stopped Working on a Trailer Towed by a 2003 Ford Windstar

Question:

The trailer lights worked for some time, but then they quit working all at once. I replaced the fuse, which was blown, but that did not repair the problem. I notice that there is no continuity on the ground white wire from one side of the controller to the other. Is this normal? Can I run a ground wire to bypass the controller? Thank-you.

asked by: Roger

Expert Reply:

Testing for continuity on the ground wire from the converter box or bypassing the ground wire on the converter box will not resolve this issue since the issue is probably one of three problems. There is either a short in the trailer wiring, a short in the converter box on the wiring harness or a short in the wiring on the vehicle.

The first step would be to disconnect the trailer and test for power at the 4-way trailer connector on your 2003 Ford Windstar using a circuit tester like part # PTW2993. You will want to activate the tail, turn and brake lights when testing for function on the 4-way connector. If there is power at the 4-way connector, then there is a short somewhere in the wiring on your trailer.

If there is no power or function at the connector, then you will want to test the wires going into the front side of the converter box by activating the tail, turn and brake light functions. If there is power going into the converter box, but not coming out, then there is a short in the converter box and it will need to be replaced.

If you do not have a signal on the wires going into the converter box, then there may be a problem with the wiring on the vehicle. If this is the case, then your taillights on your vehicle may not be working properly either and you will want to check for additional blown fuses.

If this troubleshooting does not work, just let me know what you come up with so I can help you further.

expert reply by: John H