Troubleshooting Trailer Running Light Circuit Not Working Using 4-Way to 7-Way Adapter

Question:

I conected this adapter on my tundra and the turn and hazard lights work on my trailer but regular lights wont what can i check to make them work thank you

asked by: Erick G

Expert Reply:

Sounds like the running light circuit of your trailer wiring is currently not working which is the circuit on the brown wire. This may be the adapter's fault but typically it's corrosion on trailer wiring pins that causes this type of problem so take sandpaper to the pins on the 4-way of your tow vehicle and the pins of the trailer's 7-way.

If that doesn't work make sure the running light circuit along the trailer wiring is intact without any cuts or exposed wires and make sure the grounds of the running light assemblies are connected properly. Also check the tow vehicle for any trailer wiring fuses and fix as needed.

expert reply by: Jameson C