Troubleshooting Running Light Circuit Not Functioning on Trailer Wiring
Updated 02/14/2017 | Published 02/13/2017 >
Question:
I bought a tester that plugs into the trailer plug on the vehicle and it shows that the issue is on the vehicle. would it be likely that its just the connector thats bad? This is on a 2002 gmc envoy so its got a few years of weather hitting it... didnt know if that could be possible just for that one feature to not work.. all grounds are good as well. the trailer is brand new as well. thanks for your help.
asked by: Adam
Expert Reply:
Typically it's just corrosion on the connector that causes one of the pins to not function. Have you tried cleaning the pins of the connector to see if that allows the circuit to function? Is the pin bend possibly?
Have you tested for voltage on that pin behind the connector feeding into it? If there is voltage there then the problem is in the connector most likely. If not, then the problem would be a bad fuse most likely under the hood of the vehicle.
Product Page this Question was Asked From
Featured Help Information
Miscellaneous Media
Continue Researching
- Q&A: Trailer Running Lights Do Not Work but Brake Lights and Turn Signals Do Work
- Q&A: How to Test Brake Controller without Trailer Connected
- Article: Trailer Wiring Diagrams
- Article: Brake Controller Installation: Starting from Scratch
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Q&A: Trailer Lights Left Side Turn Signal and Brake Lights Not Working
- Article: Troubleshooting 4 and 5-Way Wiring Installations
- Q&A: Troubleshooting Blown Vehicle Fuses Every Time Trailer is Connected
- Q&A: How to Hook Light Bar Up to Work with High Beams on Vehicle
- Article: Holiday 2025 | RVers’ Favorite Gear & Road Picks
- Q&A: Working Running Lights, But No Turn Signals or Brake Lights On Trailer
- Article: Testing Trailer Brake Magnets for Proper Function
- Q&A: Troubleshooting No Running Lights on Trailer but Turn Signals and Brake Lights Work


