Troubleshooting Trailer Lights Not Working with Curt 4-Way to 7-Way Adapter w/ Test Lamps

Question:

I have a 7 pin tester and my trailer lights are not working. When I plug in the tester, I see the 12 V and TM light up. I am unclear as to what that means or what needs to be addressed.

asked by: Kykel

Expert Reply:

If the 12V and TM lamps are illuminating on the Curt 4-Way to 7-Way Adapter # C57674 this indicates that the 12V circuit and trailer running lights circuits are active/powered on the vehicle. The 12V circuit is likely active at all times, while the running lights should only be powered when you have those lights activated on the vehicle.

You didn't specify which trailer lights weren't working when hooked up, but based on the test lamps I assume it's the left and right hand turn/brake signals. If this is the case I first recommend checking any towing related fuses under the hood. These can be located using the Explorer's owner's manual under the "Fuses" section.

If the fuses are okay make sure you have the Curt adapter properly grounded. The white wire from the harness should be securely attached to a clean, bare piece of metal that's free of any paint, debris, or corrosion.

If this doesn't resolve the issue please let me know and we can continue troubleshooting.

expert reply by: Chris R