Principles of Operation

Principles of Operation

With the key in the ON position, voltage is applied through the warning indicator I circuit VDC42 (GY) to the voltage regulator. This turns the regulator on, allowing current to flow from battery sense A circuit SDC02 (RD) to the generator field coil. When the engine is started, the generator begins to generate A/C which is internally converted to DC. This current is then supplied to the vehicle's electrical system through the output circuit SDC02 (RD) (B+) terminal of the generator.

Once the generator begins generating current, a voltage signal is taken from the generator stator and fed back to the regulator through the external stator circuit CDC15 (VT) or the internal stator circuit (depending on the generator application). This voltage (approximately one half of battery potential) signals the voltage regulator to open the ground of the ignition circuit, turning off the charging indicator in the Instrument Cluster (IC).

With the system functioning normally, the generator output current is determined by the voltage of the A circuit SDC02 (RD). The A circuit SDC02 (RD) voltage is compared to a set voltage internal to the regulator, and the regulator controls the generator field current to maintain the correct generator output.

The set voltage varies with temperature and is typically higher in cold temperatures and lower in warm temperatures. This allows for better battery recharge in the winter and reduces the chance of overcharging in the summer.

This is a System 1 charging system, which uses the circuit coming from the charging system warning indicator in the IC as the I-Line control input to the generator regulator, circuit VDC42 (GY). System 1 charging systems are virtually identical in design and therefore, share the same diagnostics. The circuit numbers and colors may be different, but the functions are the same.

Vehicles equipped with 2.3L engines will have 2 different generators. Early build vehicles will be equipped with Ford generators. Late build vehicles will be equipped with Melco generators. The 2 generators are the same except for the B+ terminal connection. The late build Melco generators will have an 8 mm B+ stud as compared to a 6 mm stud on the early build Ford generators. All 4.0L equipped vehicles will have the Melco generator.