How to Determine the Wire Functions to Install a 7-Way Trailer Connector on a 2002 Dodge Ram

Question:

What color wires go to what color plug attachment. My schematic reads RED wire to RED label on plug etc. All color wirtes matched to coresponding colors on plug. Right or Wrong.

asked by: Ed B

Expert Reply:

You can pretty much never go by color, only function, when wiring anything, especially on a trailer or vehicle. The colors that are the most common on a 7-Way are white for ground, brown for running lights, purple for reverse lights, black for 12-volt power, green for right turn and brake lights, blue for trailer brakes, yellow for left turn and brake lights.

To make sure you get a 7-Way wired correctly on a vehicle, you have to go by function by testing each wire with a circuit tester like # PTW2993 if needed and following the diagram in the FAQ I have linked for you. You can also use a car battery, attach each wire to the positive terminal, one at a time, and determine the functions that way.

On a trailer side you will have to trace each wire back from the connector to determine function.

expert reply by: Michael H