Replacing 4-Way Wishbone Connector on Trailer with 7-Way

Published 12/05/2018

Products Featured in This Question

35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground

(849)

$21.95

Trailer Wiring Junction Box

(822)

$33.80

Question:

Ive been looking all over the internet to try to figure out how to wire the broken 4-way plug that has 5 wires into a new 7-way plug so I can hook it directly into my truck. Saw this discussion below, but Im not gonna by yet another $20 contraption just to get these wires in the right place. Have already tried several configurations, but the running lights and the passenger tail light still dont work. This SHOULD be a pretty simple thing, and Im not afraid to run a little jumper wire or something. ??? thank

asked by: Joy

Expert Reply:

It sounds like what you have now on your trailer is a 4-Way wishbone harness that uses a running light wire on each side of the trailer. This is why there are 5 wires going to the connector instead of 4. A wishbone harness makes it a bit easier to wire a trailer since it eliminates the need to run a jumper wire between the two sides.

I am not sure how you are currently connecting the wires from the broken 4-Way to your new 7-Way plug but both of the running light wires on the trailer (typically brown in color but it may be different on your trailer) will connect to the pin at the 11 o'clock position inside the 7-Way. I have attached a diagram to assist.

The left turn/stop wire from the trailer will then go to the 9 o'clock position inside the 7-Way and the right turn/stop wire will go to the 3 o'clock pin. The ground wire will connect to the 7 o'clock pin position.

This will allow you to hook your trailer up to your tow vehicle that is equipped with a 7-Way to activate the trailer's basic signal lights.

For a cleaner setup you can certainly use a junction box like part # 38656 that you mentioned to wire together all the trailer leads but it is not required.

expert reply by: Chris R