Download 1990 ELECTRICAL Alternators & Regulators 80, 90, 100, 200 Turbo SYSTEM DESCRIPTION Bosch alternators are conventional 3-phase, self-rectifying type alternators. Bosch 110-amp alternators use 14 diodes. See Fig. 1. All alternators use 3 exciter diodes connected to stator windings. These diodes turn off the alternator indicator light and supply power to the voltage regulator while the engine is running. Bosch regulators are transistorized and integal with alternator. WIRING CONTINUITY TEST 1) Connect a voltmeter between alternator Red battery terminal wire and ground. Voltmeter should indicate battery voltage. If not, check wiring between alternator and battery.