How to Connect a Trailer-Side 7-Way Blade Connector # A7WCB to a Trailer With 5 Wires

Question:

I have a trailer with 5 wires,Brown, red, yellow, green and whiter. I want to hook these wires into a 7 way blade connector. HELP please on how and where to connect theser wires in this plug. Hooking this up to a 2010 f-150

asked by: Mike L

Expert Reply:

We offer a trailer-side 7-way blade connector that can be attached to the 5 wires on your trailer, part # A7WCB from Optronics. The linked video illustrates how this part installs. Since your trailer has only 5 wires some of these pins will not be used.

I have attached a photo showing both sides of a trailer connector with notations for a typical wiring configuration by function and color. Although these pin assignments are typical there is no guarantee that your trailer is wired the same way. So in order to know for certain which pins to use for each wire you should test the wires on your trailer to confirm the function carried on each one before connecting to the 7-way. As noted in the photo, usually the functions on the various wire colors are as follows:

white = ground
green = right turn
yellow = left turn
brown = running lights

The red wire could be used for any number of functions depending on how the trailer is equipped and wired.
If the trailer has electric brakes the red wire might be connected to the brake circuit. If it has reverse lights it could be for that circuit. If the trailer has an on-board battery the red wire could be for a 12V feed for charging the battery. You can confirm the function on each wire by testing each with a 12V battery to see what function is activated. You want to wire your trailer connector by function since color is not always a consistent indicator.

To test you will want to connect the white wire to the battery negative post and then one by one connect each of the others to the positive post to see what each one does. Once the functions are confirmed you can use the photo of the connector to attach your trailer-side connector.