Determining the Functions of 6 Wires for a Trailer Connector

Question:

I have 6 wires total...black, white, green, yellow, black, and red. After doing some research I come up with black constant hot at 1 oclock, green right signal @ 3 oclock, yellow left signal at 9 oclock, white ground at 7 oclock, and brown at 11 oclock, I dont know where red goes or if I am even correct? please advise.

asked by: Ben

Expert Reply:

The wire functions and pin locations that you mentioned are typical for standard trailer wiring on a vehicle side 7-way trailer connector, but I recommend testing each of the pins or wires with a circuit tester like part # PTW2993 to verify the function of each wire. If you are talking about the vehicle side trailer wiring, you will want to keep in mind that not all vehicle manufacturers follow the standard trailer wiring color code, so testing the wires would be the best way to determine their function.

If you already verified the functions and they operate as mentioned, then the red wire would likely be for reverse lights or an auxiliary power circuit and would attach to the center pin on a 7-way trailer connector. To determine its function, you will want to test the wire.

If the red wire does not have constant power or power with the backup lights on, then another possibility is that the red wire is for electric trailer brakes. Vehicle manufacturers typically use a blue wire for electric trailer brakes, but they do not always follow standard color codes. This wire will be difficult to test if you do not already have a brake controller installed. If you have a brake controller, then you will simply want to push the manual override to see if you have power on the red wire. If the red wire has power with a brake controller, then it would attach to the 5 oclock pin on the 7-way trailer connector.

expert reply by: John H