Troubleshooting Enclosed Trailer Dome Lights That Are Not Working  

Question:

Helpful Expert Reply:

If the dome lights are wired to the 7 way connector on the back your 2017 Ram 1500, then start by taking a circuit tester # PTW2979 to check if you have 12v at the 12v output wire on your truck's 7 way trailer connector (this is the pin in the 1 O'clock position). If you do not have 12v here, then look in the truck's fuse box and see if there is a blown fuse or a bad connection somewhere along the wire. Worst case scenario you could rewire that 12v circuit using 10 Gauge Primary Wire # 10-1-1 (sold per foot) and an In-Line Circuit Breaker - 20 Amp # 9506P.

Once that all checks out good and you have power at the 7 way then you can move to the trailer wiring and light fixture itself. Pull the dome light fixture off the trailer and check for 12V at the wiring. If you do not have 12V here, then there is a bad connection somewhere along the trailer and you may have to rewire that lighting circuit. If you have 12V and the dome light is still not illuminating then the light fixture or bulb is likely bad and will need replaced. You could replace with Optronics LED RV Interior Double Dome Light with Switch # RVILL34. If you have a separate switch controlling the lights then that could be bad. I have attached a wiring diagram for the 7 way connector on your truck.

If you have a separate battery power the lights then you will want to use the same diagnostic process from above, but instead of checking at the 7 way you will just check for power from the battery all the way to the lights, including switches and any fuses etc.

expert reply by: Andrew N

1

7 Way Diagram
(click to enlarge)