Running Lights Not Working After Converting 7-Way to 4-Way on a 1991 Ford Bronco  

Question:

Expert Reply:

So if I understand correctly, the 1991 Ford Bronco you have has a 4-Way flat trailer connector. It used to have a 7-Way and you are trying to use the wires from the 7-Way to connect to the 4-Way connector. In order to find the correct wire for the running lights, use a circuit tester, like # PTW2993. Have someone sit in the vehicle and operate the lights while you test the wires. The one that carries a constant signal when the lights are on is the running light circuit.

On a 4-Way, the exposed pin is the ground, and the pin next to that is for the running lights. The next pin is the left turn and brake light, and the last pin is right turn and brake. The remaining wires from the old 7-Way will not be needed and you can tape them up and stow them out of the way.

One issue may be that the 7-Way had its own ground, but it is not attached to the 4-Way. Make sure that the ground from the 4-Way is attached to a clean bare metal surface on the vehicle frame.

Another issue can be the trailer wiring itself. Check to make sure that both the vehicle side and trailer side connectors are free of dirt and corrosion. The main ground from the trailer should be connected to a clean metal surface on the trailer frame. Finally, the trailer lights should also be connected to a clean ground.

I have included a link to our wiring FAQ article that may be helpful to you.

expert reply by: Michael H

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