Replacing a 4-Way Connector on Trailer with 7 Wires

Updated 11/11/2014 | Published 11/10/2014

Question:

So I am replacing a flat 4-way connector attached to my boat trailer for trailer lights. I bought a standard 4-way connector to replace it and I am in the midst of splicing the matching wires. I noticed that the old connector has 7 wires leading to the 4 prongs. 1 yellow, 1 yellow/black, 1 green, 1 green/black, 1 brownish white, 1 white/black, and 1 white. I know for sure that the white is ground, yellow and green are signals/brakes. The brownish white should be running lights. This leaves me with 3 leftover wires, all black striped. What are these wires for? If I just connect the 4 wires that match the colors for the new connector, everything works except for the running tail lights. Even the marker lights turn on, but not the tail lights. Im lost and do not want to rip my trailer apart to figure this out. I imagine that those black striped wires have to go somewhere. Not sure where.

asked by: Cory B

Expert Reply:

From the information that you have given, I suspect that you have some additional ground wires on your trailer.

Without being there to actually see the trailer, my best recommendation would be to wire the connector as follows:
Green to Green for Right Turn
Yellow to Yellow for Left Turn
Yellow/Black and Green/Black to Brown for Running Lights
White, White/Black, and Brownish White to White for Ground

If the lighting on your trailer still isn't working as it should, I recommend providing power to each individual wire with a car battery to determine it's function and then wire accordingly.

expert reply by: Leah S