Tail running lights...
I have a 04 Ram. The tail / running lights are no longer working on the Left side I have checked the fuses and they are fine. The bulbs are in perfect condition. Everything seems to be plugged in. just had a new alternator installed by dodge
Check the circuit boards on the tail lights as they can become corroded and melt. Mostly 03's had it but some 04's. Other than that I would download the Service Manuals listed in my signature link below and look at the electrical diagrams




