Do All Wires on 4 to 7-Way Trailer Connector Adapter Need to be Connected for Trailer Lights to Work

Question:

Hi I have a 2003 ford ranger FX4 level 2 it came with a reciver and a flat 4 way plug, but I have always needed something more. So I went down to the local discount store ant bought a seven way plug that has a four way flat on the side. Well its already pre wired and you just plug it in to the pre existing 4 flat to make it work. Well the four flat works and the sEven doesnt. The only wires that are not hooked up are the purple blue and red one. Do they all have to be hooked up to get the basic brake lights and turn signals out of the seven?

asked by: Dustin

Expert Reply:

If the 7-way connector you purchased is not defective, once it is plugged into your functioning 4 way you should have brake/directionals and running lights. The remaining wires on the 7-way are for the brake output feed used for trailers with electric brakes, a 12-volt power feed, and an auxiliary feed that it typically used for reverse lights on the trailer.
I would recommend using a circuit tester like part # PTW2993 on the 7-way connector on the vehicle. The pin in the 3:00 position carries the right directional/brake light signal, the pin at 9:00 carries the left directional/brake signal, and the pin at 11:00 carries the running lights. Test each pin as its function is activated. If you are getting a signal at those pins, then the problem exists either with the connector on the trailer, or with the wiring on the trailer.
If you find that the connector you purchased is defective, we offer them. The part # is 37185.

expert reply by: Mike L