Grounding Problem on RV Towed by 2004 GMC Sierra

Question:

i plugged in a old rv into this 7way on the pickup and now the lights are doing wierd things-have checked all of the fuses and they are all good in the truck-with the headlights on the signal lights alternate and the breake lights are verry dim with the headlights off things seem to work???

asked by: Lon K

Expert Reply:

The fact that everything pretty much works fine until the headlights are switched on tells the story.

What you are experiencing is the classic symptoms of an insufficient ground connection. When the headlights are switched on, the wiring system of the trailer is drawing full amperage, which is when a problem will manifest itself.

Make sure that the ground connection on the RV is securely connected to clean metal on the trailer frame. You can find this connection by tracing the white wire back towards the trailer from the trailer connector.

You will also want to ensure that the lamp fixtures themselves are correctly grounded to the trailer frame, either by ground lead, or by their direct connection to the trailer frame.

I have linked you to our Wiring FAQ page, which has more information about diagnosing and repairing a weak ground connection. To see the FAQ, click on the link I have provided.

expert reply by: Mike L