Why is my trailer wiring not working?

Many trailer problems are due to a poor grounding connection, which is usually the white wire coming out of the trailer plug. If the ground is poor, lights may work intermittently or not at all. Even if the wiring to the plug is adequate, make sure that the ground connections to the trailer frame are good.

Why do my trailer lights work with one vehicle but not another?

Expert Reply: It could be a somewhat weak ground on the trailer that allows the lights to work with one vehicle but not with another. What you can try doing is running a ground wire from each of the light assemblies back to the main ground of the trailer.

Why do all my trailer lights work except running lights?

If there is no signal on the wire here, then it is likely the wire is damaged somewhere along the trailer. Try tracing the wire as much as possible from the junction box to the taillights. If you are able to find the damage, replacing the damaged section of wire will complete your trailer’s running light circuit again.

Do all trailer lights need to be grounded?

Helpful Expert Reply: Each lamp needs to be grounded either through its mounting studs being in direct contact with the trailer frame or by having a jumper wire ran from the lamp to the trailer frame. Ground the trailer connector at the front of the trailer, which will use the trailer frame as a ground wire.

Why is only one side of my trailer lights working?

Alligator clips at the wire ends make continuity connections quick and easy. If the lights on one side still aren’t working, you may have a break in the wire. To test for a broken wire, check the color of the wire going to the socket and then find that wire on the connector in front.

How do I make my trailer ground better?

The best way to secure a ground to a trailer or any metal surface is to do exactly what you described. You will want to make sure you have a ring terminal like part # DW05702-1 attached to the ground wire first. Then drill a hole in the surface you want to attach the ground to.