Troubleshooting Trailer Lights that All Come On When Key Is Turned On

Updated 05/18/2015 | Published 05/16/2015

Question:

1995 Ford Bronco- Headlights off- Turn key to start truck- All Trailer lights come on, tail, side markers, etc.. Tail Lights, Brake Lights, Turn Signal/Stop Lights All work as they are supposed to while driving. Thats the good thing. Headlight switch on/off does not change anything, always on. This causes lights to be on day and night. Trailer lights only turn off when truck key is turned to off. Pollak 7-Way Trailer Tow Connector Plug Configuration 1- RED- Left Turn and Stop 2- White- Ground 3- Blue- Electric Brakes- Not Used- I have Surge Brakes 4- Green- Right Turn and Stop 5- Black- Battery- Not Used 6- Brown- Running Lamps 7- Yellow- Backup Lamps- Not used I have wired the following Running Lights- Orange Truck to Brown Plug Left Turn/Stop Lights- Yellow Truck to Red Plug Right Turn/Stop Lights- Green Truck to Green Plug Ground- White Truck to White Plug The Orange wire on the truck is hot only with key on. This makes sense why my lights are always on. Then which wire do I connect to the Brown Plug wire, Running Lights to on the truck? Where does the Orange Truck wire connect? Can you help determine why all my come on when key is turned? Thanks for your help...........

asked by: Blair F

Expert Reply:

The issue you are having is the circuit you chose to power the running lights circuit of your trailer 7-way. If that circuit sees voltage when the key is turned on and your trailer is connected then all of the trailer lights will illuminate when the key is turned on.

You need to find a circuit that only sees voltage when the running lights/head lights are on to run to the brown wire. The running light circuit of your truck should work well.

I attached a couple help articles on trailer wiring for you to check out as well.

expert reply by: Jameson C