Normal Operation
WARNING: This page is about a different car, the 2013 Ford F-550 Super Duty, 2013 Ford F-450 Super Duty, 2013 Ford F-350 Super Duty, and 2013 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.
The PCM monitors the generator output via the GENMON circuit (generator field terminal circuit). If the PCM cannot read the GENMON circuit due to an open or short to ground, when the engine rises above approximately 2, 000 RPM, the generator defaults to a steady voltage of approximately 13.5 volts and the PCM sends a message over the High Speed Controller Area Network (HS-CAN) to the Instrument Panel Cluster (IPC) through the Body Control Module (BCM) to illuminate the charging system warning indicator lamp.
- DTC P0625 (Generator Field Terminal Circuit Low) - The PCM sets this DTC if the GENMON circuit is shorted to ground, the "A" sense circuit is open or the B+ circuit is open. This DTC also sets by a faulted PCM or generator.
- DTC P0626 (Generator Field Terminal Circuit High) - The PCM sets this DTC if the GENMON circuit is open or shorted to power. This DTC can also be set by a faulted PCM or generator.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Engine, generator and battery grounds
- Battery
- Generator
- PCM