Generator Field Not Switching Properly

Name of Code:
Generator Field Not Switching Properly

When Monitored:
With the ignition key on and the engine running.

Set Condition:
When the PCM tries to regulate the generator field with no result during monitoring.


Theory of Operation:
The PCM tries to maintain a system voltage between 12.9 volts and 15.0 volts. The voltage determined by the PCM as the final goal for the charging system is called "control voltage". This control voltage is determined from the battery temp sensor (ambient sensor). The control voltage is compared to the sensed voltage continuously during running. If the sensed voltage is less than the control voltage, the PCM will supply more ground to the field circuit. If the sensed voltage is more than the control voltage, the PCM will supply less ground to the field circuit.

Possible Causes:
- Field driver circuit open or shorted
- Generator internal open or short
- PCM failed