2003 Ram 2500 7 Pin Trailer Wiring Diagram. I drew this crude diagram to help explain. You can test the white wires with an ohm meter, white on the flat four to the thick white wire should have continuity with one of the.
The previous owner backed into a telephone pole and da. There is a wire tucked under the dash - it will be behind the kick panel on the lower left. It gets complicated when you have trailers with more cables, and in this case, you need an adapter to make the connections.
Wiring your four-pin trailer can be a challenge when you first do it, but it's a simple do-it-yourself task.
There is a long thread on this forum that has all the part numbers, it is all about trailer hitches.
You should be able to easily find a Curt harness that plugs into that pig tail and give you the required wiring plug for your trailer. I drew this crude diagram to help explain. Offroaders Staff Editor Trailer & Towing.