Troubleshooting Trailer Ground Issue on a 1995 Ford F-250
Question:
When I turn on my clearance lights the trailer clearance lights come on and work properly. If I leave the clearance lights on and turn on any of my left or right signals all lights on my trailer blink and load down. If I shut off my clearance lights and turn on my left or right signal and brake lights they work properly on the trailer. I checked all of the wiring and seems proper and the trailer lights work fine with two of my other vehicles. Any suggestions
asked by: Mark
Expert Reply:
What you are describing sounds very much like a ground issue. The trailer lighting functions work properly until the running lights are used. When the running/clearance lights are activated, full amperage is drawn through the system which is when a problem like this will show itself.
Typically, the problem is usually found either at the point where the ground wire from the trailer connector grounds to the trailer frame, or at the physical connection between the lamp and the trailer frame. Since you do not have this problem when using the trailer with other vehicles, the trailer is pretty much ruled out.
This makes me suspicious of the trailer connector on your truck. Closely examine the trailer connector on the truck. Check the pins for any damage or corrosion. If you can see any green corrosion on the connector pins, there is a chance that the corrosion has spread to the interior of the connector and is preventing a good connection. You will also want the check the ground connection from the trailer connector on the vehicle. Look for a white wire coming out of the back of the connector that should be grounded to the vehicle frame. Make sure this connection is tightly connected, and is not corroded.
If these areas check out, please get back with me, and we will explore some other possibilities.
