Circuit Description

The PCM initiates generator operation by supplying 12V, through an internal resistor, to the generator "L" terminal over CKT 225. See Figure . See WIRING DIAGRAMS  . The generator regulator applies voltage to the rotor as a PWM signal to energize the field windings. The regulator controls the charging system voltage and therefore the ampere rate of battery charge and power supplied to the car by increasing the duty cycle.

The regulator controls the system voltage according to temperature and system voltage as measured at the "S" cavity of the generator harness on CKT 725. A temperature sensor is mounted in CKT 725 at the battery. At decreased temperatures, the resistance increases and causes the required higher charging. If the regulator measures very low voltage it defaults to internal voltage sensing.

A/C voltage is generated in the stator and changed to D/C voltage by 6 diodes in the rectifier bridge. If a diode is open, the maximum amperage output of the generator will be reduced by 10%. If a diode is shorted, the maximum output will be reduced by about 1/3. A shorted diode may set a code P110 and cause the generator to have a "growling" noise due to the electrical imbalance.

Maximum generator output will occur at 2000 engine RPM. At idle, output may be 1/3 of maximum output.