How to Wire a Trailer and Vehicle Side 7-Way Trailer Connector

Updated 10/14/2013 | Published 10/11/2013

Question:

i am trying to get the marker /clearance light to work on a cattle trailer i think it may be the connector to the truck but the colors are throwing me off how should i connect them to plug into truck , the colors are as fallows red, black,green,blue,yellow,brown and what is really confusing is the there is no white wire the plug is a 7way blade what is the best way to wire it to get all light working

asked by: Todd S

Expert Reply:

You cannot go by wire color in most cases because there is no real standard. We have blue for trailer brakes, yellow for left turn/brake lights, brown for running lights, green for right turn/brakes, black for 12 volt power, white for ground, and purple for reverse or AUX power at the center.

Since your lights are not working something must not be in the right spot. What you can do is touch each wire to the positive terminal of a separate 12 volt battery and see what lights up. Then you can wire the trailer side connector accordingly. Follow the diagrams I have included. They are labeled vehicle side and trailer side so you will not confuse the 2.

expert reply by: Michael H