Trailer Left Side Brake, Turn Signal, and Running Lights Not Working

Published 08/27/2015

Question:

I called earlier today. My issue is I have a 7 blade connector in truck and 7 blade connector from trailer. My left lights arent working properly. I opened the connector on trailer and found that there were only 5 wires inside. Not knowing much about wiring I am confused. I tested the 7 connector from truck and every blade works and performs correct. My wiring If you are looking at trailer connector the top right blade is green. Top left is black. Second Blade on left one below black is a yellow/brown wire. The blade below this is white wire. The center is yellow wire. Top right blade is green. I have a battery for the brake but trailer no breaks. Now my right blink and running lights work they have green and brown going into them I have attached ground to body. My left tail lights do not work properly they have the yellow/brown wire attached to them. Please help my confusion is how does the left tail light get signal. it doesnt have to be hooked up to the blade that controls the left blinker that is own 7 connector on truck.

asked by: Paul

Expert Reply:

Since everything is working on the truck side the issue must be on the trailer side. I have included a picture that shows the pin functions of both a vehicle and trailer side 7-Way. You will need to check the configuration on the trailer side to determine if it matches up to what the truck side has.

In the pictures though you have to ignore the colors and focus only on the functions. On the vehicle side if you are looking at the pins the left turn signal and brake lights are in the 9 o'clock position so on the trailer side it would be in the 3 o'clock position.

There is only one running light circuit for all of the running lights on the trailer. It is possible that something is not wired to the right pin on the trailer side connector or the wiring to the left side is damaged and needs to be replaced.

expert reply by: Michael H