Troubleshooting Trailer Wiring Blinker Brake Lights on a 1997 Ford F150 Towing a Haulmark Trailer

Question:

I have a Haulmark tandam trailer with 7 pin harness and the 97 Ford pick up has a 4 pole connector.Can you tell me how to wire a 7 pin up to the 4 pole? I cant get the left Brake/blinker,running light to work.

asked by: Randy

Expert Reply:

I attached an FAQ article on how wiring that should be very helpful for you to check out. But basically the problems you are experiencing sound like they are coming from the 4-way, since the trailer light functions are controlled by the 4-way.

I would recommend you use a circuit tester like out part # PTW2993 to test the 4-way by function first to make sure there is nothing wrong with the 4-way before you attempt to convert it to a 7-way.

If that all checks out when you convert to the 7-way you will just plug in the Adapter # 30717 and all of the 4-way functions should work well coming through the # 30717.

If at this point you are still experiencing problems with the tail light functions the problem is in the trailer. You will want to check your trailer wiring as the problem is there. You should check for wiring problems such as bad grounds, or loose and exposed wiring.

expert reply by: Jameson C