Charging Circuit Operation

The battery supplies voltage to generator at all times. During engine start-up I/P cluster performs a bulb check by illuminating charge telltale for three seconds. The generator begins charging when the ECM supplies 5 volts on the L-terminal circuit or when engine is above 2500 RPM. The system charges the battery and provides power to vehicle electrical devices. The ECM can increase idle speed to boost generator output if battery voltage drops below specifications. If the charging circuit malfunctions, the ECM signals the BCM, then signals the I/P cluster to illuminate the charge telltale. The ECM communicates with the BCM by CAN link on circuits 2500 and 2501. The BCM communicates with the I/P cluster by class 2 on circuit 1807.