Description & Operation

WARNING: Vehicles are equipped with air bag supplemental restraint system. Before attempting any repairs involving steering column, instrument panel or related components, see DISABLING & ACTIVATING AIR BAG SYSTEM in AIR BAG RESTRAINT SYSTEMS article in RESTRAINTS.

CAUTION: When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.

Prizm is equipped with a Denso 80-amp generator. Generator consists of a "Y" type stator, rectifier bridge, rotor with 2 slip rings and 2 brushes, a conventional pulley, an internal fan and internal voltage regulator. The Integrated Circuit (IC) voltage regulator is a solid state unit mounted to rectifier end frame. Brushes carry current through 2 slip rings to field coil mounted on rotor. A rectifier bridge containing 8 diodes is connected to stator windings.

Generator provides voltage to operate vehicle's electrical system and to charge its battery. A magnetic field is created when current flows through rotor. This field rotates as rotor is driven by engine, creating AC voltage in stator windings. AC voltage is converted to DC by rectifier bridge and is supplied to electrical system at battery terminal.

When engine is running, and generator is rotating, voltage is generated in stator. Generator's voltage regulator senses this voltage and controls current to rotor, thereby controlling output voltage. Rotor current is proportional to electrical pulse width supplied by regulator. When engine is started, regulator senses generator rotation by detecting AC voltage at stator through an internal wire. Once engine is running, regulator varies field current by controlling pulse width. This regulates generator output voltage for proper battery charging and electrical system operation. Generator "F" terminal is connected internally to voltage regulator. When voltage regulator detects a charging system problem, it grounds this circuit which illuminates the charge indicator lamp. The system voltage sense circuit receives ignition voltage through GAUGE fuse in junction block 2. This voltage is used by the regulator as reference for system voltage control.

When ignition switch is turned to RUN, charge indicator turns on for a few seconds (bulb check), then turns off. When the generator is not rotating, regulator provides a ground which causes charge indicator to illuminate. When generator is rotating, regulator provides a separate output voltage to charge indicator. Since equal voltage is now provided to both sides of charge indicator, lamp loses its ground and goes out.