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Starting and Charging Diagnosis
Schematic:
DTC PARAMETERS
The ECM Will set DTC P0621 if it detects an open in circuit 225 with engine RPM > 40.
DTC PARAMETERS
The ECM monitors the generator signal continuously.
DTC P0621 is a type D code which will not illuminate the telltale.
Diagnose intermittent problems with Scan tool by monitoring ignition 1 voltage. Wiggling wires with engine running may identify an intermittent open circuit.
If the L-terminal circuit is open, the generator will not charge when engine speed is below 2500 rpm. Above 2500 rpm, the generator field windings will self excite and charge.
Diagnostic Chart:
