Troubleshooting Trailer Wiring that Dims When Headlights Come On

Question:

I tried to wire my trailers using the existing 4 wire on the Ranger and seems that the electrical load is to great, One the truck brake is applied, the running lights on the trailer dim and some of my running lights on the truck come on. The brake light no front of running lights on the truck are dim one the brake is applied in the truck. I assume, I need a converter and use the existing 4 wire connecter on the truck for the input interface to the converter? Grounding seem to be good. I use my trailer with my Ford F250 and Nissan Xterra with no problems. Never had this issue before with trailer lights. Any recommendations of parts or possible power-lights trailer converter.

asked by: Darrell P

Expert Reply:

Normally if the lights dim on trailer wiring after activating the head lights or running lights of the vehicle that means you need a better ground for the trailer's wiring. Typically cleaning up where the ground wires attach to the truck frame will take care of this. Other option is run a jumper wire from the grounds of each light back to the main ground wire of the trailer harness as well.

Sounds like you have trailer wiring installed on your 2011 Ford Ranger already but the Curt harness part # 56014 is an easy install and would work better if you attempted to hardwire to the vehicle's taillight circuits. This probably would clean up the random circuits on your truck activating as well.

expert reply by: Jameson C