Wiring in a New 7-Way Trailer Connector on a Boat Trailer with Unknown Wire Functions

Question:

I need a new trailer plug not sure what kind it has a 7 pin on it now but I can not find one that matches. I have 2 yellow and 4 brown plus 2 green and white for ground. I have figured out the turn signals , running , and brake lights. I have 2 brown and 1yellow , 1green wire left can’t find a plug that matches. I loose them in the frame half way back on the trailer.

asked by: Sam

Expert Reply:

Since there isn't exactly a standard for trailer wiring color those wires could be for all sorts of stuff. But since you have found the turn signals, running lights, and brake lights then that will narrow it down.

A 7-Way trailer connector will also have a circuit for 12 volt power, a circuit for electric brakes, and a circuit for reverse lights. If the trailer does not have any of those items then you won't have to do anything with the wires.

To make things easier on yourself I recommend installing a junction box, # HS381-9000. You will also need wire # DW04914-1 to go from the junction box to the lights and other circuits as needed. This wire is sold by the foot. I also recommend heat shrink butt connectors # DW05744-5 and # DW05745-5 since you have a boat trailer and need to seal out moisture.

Another possibility is that someone wired in that 7-Way because they wanted to run a bunch of ground wires back to the main trailer connector. So if all of those additional wires were attached to the ground pin (7 o'clock position on back of trailer side 7-Way where the wires attach) that would be the case.