I have a 1993 300E and have an issue with the passenger side tail light. All other lights in the cluster work, I.e. turn signal, brake light, etc. I used a wire tester and there is no power to the lamp. Can someone help me out with where the rear tail light wires come from? I would like to check the power at the source.

Also, does anyone know where to purchase a rheostat? My interior dash and center console lights stopped working as well. Thanks!