Principles of Operation

After the engine is started, voltage is applied through the warning indicator I circuit 904 (LG/RD) from the powertrain control module (PCM) to the voltage regulator. This turns the regulator on, allowing current to flow from the battery sensing A circuit 35 (OG/LB) to the generator field coil. At this time, the generator begins to generate current which is then supplied to the vehicle's electrical system through the output (B+) terminal of the generator.

With the system functioning normally, the generator output current is determined by the voltage of the A circuit 35 (OG/LB). The A circuit 35 (OG/LB) 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 will vary 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.

Battery Positive Output (B+) Circuit 38 (BK/OG)

The generator output is supplied through the battery positive output (B+) terminal circuit 38 (BK/OG) on the back of the generator to the battery and electrical system.

I Circuit 904 (LG/RD)

The I (ignition) circuit 904 (LG/RD) is used to turn on the voltage regulator. This circuit is powered by the PCM after the engine is started. This circuit is also used to turn the charging system warning indicator on if there is a fault in the charging system operation.

A Circuit 35 (OG/LB)

The A (battery sense) circuit 35 (OG/LB) is used to sense battery voltage. This voltage is used by the regulator to determine generator output. This circuit is used to supply current to the generator field (rotor). The amount of current supplied to the rotor will determine generator output.