Pinpoint Test C : P0620: Notes

Diagnostic Overview 

Diagnostics in this service information assume a certain skill level and knowledge of Ford-specific diagnostic practices. Refer to Diagnostic Methods in Service Information for more information.

Refer to CHARGING SYSTEM for schematic and connector information.

Normal Operation and Fault Conditions 

The PCM monitors the generator output via the generator monitor (GENMON) circuit. The PCM uses the generator command (GENCOM) circuit to command the generator to either increase or decrease output. If the GENCOM circuit (generator control circuit) or the "A" sense circuit are open or shorted to ground, the PCM will not be able to control the generator output. When the engine speed is greater than 2, 000 Revolutions Per Minute (RPM), the generator defaults to a steady voltage output of 13.5 volts and the PCM sends a request to the IPC to illuminate the charging system warning indicator. A GENCOM circuit fault can be confirmed by viewing the PCM PID generator command line fault (GENCMD_LF) (YES status indicator fault).

DTC Fault Trigger Conditions 

Possible Sources 

• Fuses
• Generator
• PCM
• Wiring, terminals or connectors

Visual Inspection and Diagnostic Pre-checks 

• Inspect fusible links.
• Inspect the wiring, terminals or connectors.
• Inspect for loose or corroded connections.