Illumination Rheostat
Remove rheostat from instrument panel. Using a fused jumper wire set, connect battery voltage to rheostat switch terminal No. 3. Connect ground to rheostat switch terminal No. 2. Connect 12-volt test light between rheostat switch terminals No. 1 and 3. See Fig 1 . Rotate rheostat knob in both directions. Test light should get gradually brighter in one direction and gradually dimmer in opposite direction without flickering. Replace rheostat switch if it does not operate as specified.