Troubleshooting Boat Trailer When Running Lights Quit Working

Question:

my lights have worked for years, but now, the running lights dont work. do you know what this might be. toyota 4 runner with the grey wire to release the brakes on the trailer

asked by: Mark G

Expert Reply:

When the lights have been working for a period of time and then stop working it is usually an issue with the ground wire. A loose or damaged or corroded ground will cause any number of issues.

I recommend first physically checking the wires on the vehicle and the trailer and see if there are any signs or crimped, loose, or damaged wires. Then check the trailer harness on the vehicle and trailer. Look for any signs or corrosion or damaged pins.

If they all look like they are in good shape I recommend using a circuit tester like part # PTW2993.

With the trailer unhooked, have someone run through the functions while you check the 4Runner's trailer connector pins. If they all check out you can then hook up the trailer and check the wires coming from the trailer connector while someone runs through the functions. On the trailer look for any signs of corrosion, loose or damaged wires and fix as needed.

I have attached links to a couple of helpful articles you can check out.

expert reply by: Jeffrey L