Installing a 4-Way Flat Trailer Connector on a 1971 Holsclaw C1700 Boat Trailer

Question:

Just purchased 1971 subject trailer. It has a 4 square plug and my vehicle Ford explorer is a 4 flat. Is there any adapter or do I need to cut off square and connect flat? If so is 1971 wiring same as currently is today? thanks

asked by: John B

Expert Reply:

The best thing to do is to remove the 4-Way square on the trailer and replace it with a 4-Way flat to match the connector on your Ford Explorer. A 4-Way flat and 4-Way square are not wired the same and chances are the colors will not match up either. You will need to trace the wires back to determine the function of each and wire in a new 4-Way flat according to the description below.

First you will need a 4-Way, like the 4-Pole Trailer End Connector, # 18004. Match the functions of the trailer wiring with the wires on the 4-Way as follows.

White = ground
Brown = running lights
Yellow = left turn and brake
Green = right turn and brake

This is a more standard way to wire the trailer. It will also help with troubleshooting problems should they occur in the future. I have included a link below that shows a typical wiring diagram and the functions of various connectors.

expert reply by: Michael H