Device for monitoring the serviceability of optical indicators

Claim 1

In an electrical control system for a machine having an electrical circuit including a battery, a normally open switch which is closed to initiate machine operation and coupled in series with the battery, a series connected normally closed switch which is opened upon initiation of machine operation, a plurality of warning lamps coupled in parallel with the battery and each of which is operably connected to a sensor for generating a control signal effective to illuminate one of said warning lamps for displaying a visual indicator signal, and a testing system for displaying the operability of each of the warning lamps during machine operation, the improvement comprising a plurality of diodes each one of said plurality mutually exclusively electrically coupled in series to one of said plurality of warning lamps and to one terminal of a plurality of normally open function control switches actuable to a closed current-coupling position in response to a control signal from said sensor to illuminate said one warning lamp of said plurality, and a normally open test switch electrically coupled in parallel to said normally closed switch and in series with said plurality of diodes, actuable into a closed current-coupling position to simultaneously electrically couple all of said diodes to the battery for simultaneously illuminating said plurality of warning lamps.