Left Turn Signals Not Working When Hooking Up Utility Trailer To Truck


i just hooked up my utilty trailer to my truck. when i put my right signel on it works but when i put my left signel on even the signel on my truck wont blink. very puzzled

Expert Reply:

Sounds like it is a ground problem. I would start with checking the ground of the left tail light of your utility trailer to make sure it is making a good ground.

The tail light assembly is grounded to the trailer by either a separate ground wire to the frame or by the bolts of the tail light assembly being attached to the frame of the trailer. You will want to make sure the tail light assembly is fastened to the metal trailer frame securely and making a good ground. If it has the ground wire instead, make sure the wire is attached to clean metal on the trailer frame.

The next ground to check is the connector on the trailer. It should have a ground wire from the connector attached to a clean surface on the trailer frame.

The last ground to check is the connector on the tow vehicle. It should have a ground wire attached to a good clean ground on the vehicle.

I would also recommend to use a circuit tester like the part # 40376, and test the wire for the left turn signal going into both connectors and coming out to find out if the connectors are bad.

I am including a link to a FAQ page on trailer wiring.

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