Charging System: Description and Operation

The charging system is an integral part of the battery and starting systems. Because all these systems work in conjunction, diagnose and test them together.

Circuit A0 from the battery connects to a bus bar in the [1][2]Power Distribution Center (PDC). Circuit All connects to the PDC bus bar and the output terminal of the generator. A fuse in the PDC between A0 and All circuits protects the charging system. Circuit Z1 provides ground for the generator.

On the diesel engine applications an additional battery is used. Circuit A0 connects between the battery positive terminals of the batteries.

When the ignition switch is in either the START or RUN positions, it connects battery voltage from circuit A1 to the A21 circuit. Circuit A21 powers circuit F18 through Fuse 9 in the fuse block. Circuit F18 connects to the coil side of the Automatic Shut Down (ASD) relay Circuit A1 originates in the PDC and is connected to battery voltage. A 40 amp fuse in cavity 3 of the PDC protects the A1 circuit.

When the ASD relay energizes, it contacts connect circuit A14 from the PDC to circuit A142. Circuit A142 splices to connect to the generator connector supplying battery voltage to the generator field.

The Powertrain Control Module (PCM) has an internal voltage regulator that controls generator output. Circuit K2O connects to generator and PCM cavity 20. The PCM controls the generator field on the K2O circuit.

When the engine operates and there is current in the generator field, the generator produces a B+ voltage. The generator supplies B+ voltage to the battery through the A11 and A0 circuits.