Generator Functional Check

GENERATOR FUNCTIONAL CHECK
The generator functional check is designed to test the generator for undercharging or overcharging.






CHART B






Circuit Description:
The PCM initiates generator operation by supplying 12V, through an internal resistor, to the generator "L" terminal over CKT 225. 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 through internal voltage sensing.

A/C voltage is generated in the stator and changed to DIC 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 30% 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 should be 30% of maximum output.

NOTES ON FAULT TREE:
1. Always diagnose codes before performing functional check, This will test the PCM ability to detect generator faults and out of range voltage conditions.

2. Over-voltage conditions may be caused by; defective rotor or regulator. Overcharging may be evidenced by low electrolyte level in the battery.

3. Insufficient amperage output may not set codes but result in marginal battery charging if driving habits involve short trips and prolonged idling, especially in warmer weather, Low output may be caused by; defective regulator, open or shorted diode, contamination of brushes.

No output conditions may be caused by; defective regulator, open or shorted rotor, stator damage, brush wear.

NOTES ON INTERMITTENTS:
If complaint is no-start and generator functional test is okay and no codes are set, refer to battery diagnosis.