Troubleshooting Trailer Running Lamp Not Functioning on Trailer Towed by 2018 Ram 3500

Question:

I have a ram 3500 2018 I have brake lights I have turning lights on my trailer when hooked up to my pick up but no running lights

asked by: Frank

Expert Reply:

The first thing you'll want to do is turn on the truck's running lights, and use a circuit tester like # PTW2993 on the pin in the 11:00 position in the 7-way trailer connector. If that pin is showing power, the problem is in the trailer wiring. The BROWN wire typically carries the running lamp circuit on trailers, but occasionally it could be green. From the trailer connector, trace that circuit rearward all the way to the taillights. Look for loose connections or cracked or worn wire insulation that would allow the copper wire to short out on the trailer wiring.

If you do NOT get a signal on that pin, you have a blown or missing 20amp fuse in location # F29. If the fuse is blown, you'll want to be sure to find and repair the short that caused the fuse to blow, otherwise you'll keep blowing fuses.

expert reply by: Mike L