7 Pin To 4 Pin Trailer Wiring Diagram. Wiring your four-pin trailer can be a challenge when you first do it, but it's a simple do-it-yourself task. Please see the Trailer Wiring Diagram and Connector Application Chart below.
It gets complicated when you have trailers with more cables, and in this case, you need an adapter to make the connections. If you follow our trailer wiring. Seven-pin connectors are rarely used on trailers for local use.
If you follow our trailer wiring.
I traced the wiring back to the engine compartment and found a blue wire.
It gets complicated when you have trailers with more cables, and in this case, you need an adapter to make the connections. We store it in the barn in Maine over I found a diagram on the web (see attached), but can't tell if the diagram is from the front or rear of the connector - ie. On my set up, the weight of the wiring harness is enough to make it droop downwards just enough that it starts to become disconnected.