Jaco This is a long shot but mine is that way also, and the other power and ground leads are for back lighting. My tach needs positive power just to work and then a separate circuit for the lighting, so that you can connect it to the headlight switch and light it at night. Unline the other gauges that have a bulb that inserts, it is a sealed unit...
Colin Rainey brokerpilot9...@earthlink.net
