Its the small knob above the headlight switch on the left side of the steering wheel. Hey if you did not know about that maybe the lights are just turned down. If that is not the problem pull the light and rheostat knobs off. then you can pull the plastic cover surrounding them off. Underneath there are 1 or 2 scews holding the metal mounting plate for the switches. Take those off and pull out the plate with the switches. Unplug the wires to the rheostat. you can do a quick test by putting all of the wires together. IF the lights work its your rheostat. IF they still don't the problem is elsewhere. Be carefull the rheostat wires are live when the battery is connected and the light switch is on. To be safe you should unhook the ground lead to the battery when handling the wires, unless you car comfortable handling live wires.