Normal Operation

The PCM monitors the generator output via the GENMON circuit. The signal that is monitored by the PCM on the GENMOM circuit is a controlled frequency range. If the signal is outside of this prescribed range, the PCM will be unable to read the signal. When the engine rises above approximately 2,000 RPM, the generator will default to a steady voltage of approximately 13.5 volts and the PCM will send a request to the Instrument Cluster (IC) to illuminate the charging system warning indicator lamp.

• DTC P065B Generator Control Circuit Range/Performance - If the input frequency was continuously less than 80 Hz or more than 200 Hz the PCM will set this DTC.

This pinpoint test is intended to diagnose the following: 

• Wiring, terminals or connectors
• Generator
• PCM