This might help. I looked up the switch in the service manual, and there is terminal near the end of the switch closest to the dash panel labeled I. This is for the instrument lights. Sometimes you have to loosen the headlight switch and drop it below the dash to see this. The other terminals are marked H (headlights) P (parking lights) R (tail lights) D (dome light) A (stop lights) and B (battery). If you get no voltage at the I terminal, the wire coil in the rheostat (the ceramic part that turns when you turn the ****) may be bad.