Steps for Troubleshooting Trailer Lights

1. Start at the Tow Vehicle:
   • Ensure both the trailer and tow vehicle harness are securely plugged in.
2. Check Fuses:
   • Refer to the tow vehicle owner’s manual to locate the proper fuses for the trailer lights.
   • Inspect the fuses and replace them if needed.
3. Confirm Power:
   • Ensure the tow vehicle’s headlights are on to get the trailer clearance lights to illuminate.
   • Verify that there is power coming from the tow vehicle.
4. Check Ground Connection:
   • Ensure the white ground wire on the trailer plug is making a good connection to the trailer frame.
5. Further Troubleshooting:
   • If all trailer lights are still not working after confirming power and a good ground connection:
     • The trailer’s harness may be compromised and need replacement.
     • For very large trailers, check if the plug has been disconnected from the trailer’s main harness.