In the single generator system, with the key in the ON position, voltage is applied through the charging system warning indicator I circuit to the voltage regulator. This turns the regulator on, allowing current to flow from the battery sense A circuit to the generator field coil. When the engine is started, the generator begins to generate alternating current (AC) which is internally converted to direct current (DC). This current is then supplied to the electrical system through the output terminal (B+) 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 stator circuit 4 (WH/BK). This voltage feedback signal (typically one-half of the battery voltage) is used to turn off the charging system warning indicator on the single generator system. Gas engines have an external stator circuit and diesel engines have an internal stator circuit.
With the system functioning normally, the generator output current is determined by the voltage of the A circuit. This A circuit voltage (battery sense circuit) is compared to a set voltage internal to the regulator, and the regulator controls the generator field current to maintain correct generator output.
The set voltage varies with temperature and is typically higher in cold temperatures than in warm temperatures. This allows for better battery recharge in the winter and reduces the chance of overcharging in the summer.
The single generator system consists of the generator mounted on the top right of the engine (diesel) or top center of the engine (gas). The gas engines use a 3G 115-amp generator with a 2.71:1 pulley ratio. The 6.0L diesel engine uses a 6G 110-amp (standard) generator with a 2:79 pulley ratio and a snowplow option is available for only the 6.0L diesel that includes a VR42 140-amp generator with a 2.79:1 pulley ratio.
Positive Battery Output (B+) Circuit 36 (YE/WH) (Gas Engines) / Circuit 1119 (RD) (Diesel Engines)
The generator output is supplied through the positive battery output (B+) terminal on the rear of the generator to the battery and the electrical system.
I Circuit 904 (LG/RD) Single Generator
The I (ignition) circuit is used to turn on the voltage regulator. This circuit is powered up when the key is in the ON position. Voltage is supplied from the ignition switch to the central junction box (CJB) fuse 45 (10A), then to the instrument cluster and through the charging system warning indicator (battery icon) to the generator. This circuit is also used to turn the charging system warning indicator on if there is a fault in the charging system operation.
S Circuit 4 (WH/BK) (Gas Engines)
The S (stator) circuit 4 (WH/BK) is used to feed back a voltage signal externally from the generator stator to the regulator. This voltage feedback signal (typically half the battery voltage) is used by the regulator to turn off the charging system warning indicator. Gas engines have an external stator circuit and diesel engines have an internal stator circuit.
A Circuit 35 (OG/LB)
The A circuit or battery sense circuit is used to sense battery voltage. This voltage is used by the regulator to determine generator output. This circuit is also used to supply current to the generator field, which determines generator output.