Connecting Trailer Wires Based on Function For Proper Lighting

Updated 03/23/2018 | Published 03/22/2018

Question:

I have all functions on the driver side flat 4 plug but have none on the right side. i connected yellow to red and brown to brown plus both white? to the frame on the left. Brown to black and green to green plus 2 white to the frame on the right. nothing works on the right. The two white on each side are one on the light fixture and one channeled through the trailer frame. do I need to attach all 4 white wires to the frame?

asked by: Mick R

Expert Reply:

I've attached a couple of articles to assist in your wiring. The color combinations you gave don't really make much sense which is not all that odd, but it does mean you will need to use a circuit tester like # PTW2993 to determine the functions of each wire. You will need to start with the trailer wiring connection to test functions and then match the wires on your trailer to the correct location. Only the ground wire will be connected to the trailer frame or you will short your wiring. There can be multiple ground wire connections as each light can have a separate ground connection to the trailer frame if you like. You will want to make sure the ground connections are bare metal to metal because a faulty ground even if it looks good to the eye can make a light not function correctly. I've attached a video to assist as well.

expert reply by: Jason S