Description And Operation
DESCRIPTION
The charging system consists of the following components:
| 1. | Refer to GENERATOR . |
| 2. | Refer to BODY CONTROL MODULE (BCM) . |
| 3. | Refer to INTELLIGENT BATTERY SENSOR (IBS) . |
| 4. | Refer to POWERTRAIN CONTROL MODULE (PCM) with internal Electronic Voltage Regulator (EVR). |
OPERATION
The PCM uses the Generator field duty cycle signal circuit or F-terminal circuit, to monitor the duty cycle of the generator. The Generator field duty cycle signal circuit connects to high side of the field windings in the Generator. A Pulse Width Modulated (PWM) high side driver in the voltage regulator turns the field windings ON and OFF. The PCM uses the PWM signal input to determine the Generator load on the engine. This allows the PCM to adjust the idle speed to compensate for high electrical loads. The PCM monitors the status of the generator field duty cycle signal circuit. When the key is in the RUN position and the engine is OFF, the PCM should detect a duty cycle near 0 percent. However, when the engine is running, the duty cycle should be between 5-95 percent.
| 1 - Generator Field Circuit |
| 6 - Generator |
| 2 - PCM |
| 7 - Resistor (Gasoline Engines Only) |
| 3 - Battery Sense Input |
| 8 - Generator Case Ground |
| 4 - Power Distribution Center (PDC) |
| 9 - B(+) Circuit (Generator Output) |
| 5 - Battery |
| 10 - B(+) Sense Circuit |
| 11 - Starter |
The charging system is turned on and off with the PCM (2) and ignition switch with engine running. The field circuit will not be energized until engine is running and ignition switch is on. This voltage is connected through the PCM (2) and supplied to the generator field circuit (1) at the back of the generator (6). The generator (6) is internally grounded through the generator case ground (8). The generator (6) regulates the field using Pin 1 of the field connector (High side driver).
The generator (6) is driven by the engine through a serpentine belt and pulley arrangement.
The PCM (2) receives a voltage input from the generator (6) via the B(+) sense circuit (10) and also a battery sense input (3) from the BCM (4), it then compares the voltages to the desired voltage programed in the EVR software and if there is a difference it sends a signal to the generator EVR circuit to increase or decrease output. It uses PWM to send signals to the generator circuitry to control the amount of output from the generator. The amount of DC current produced by the generator is controlled by the EVR circuitry contained within the PCM (2).
All vehicles are equipped with On-Board Diagnostics (OBD). All OBD systems, including EVR circuitry, are monitored by the PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC). The PCM will store a DTC in electronic memory for certain failures it detects.
Voltage is monitored at B(+) sense circuit (10) to insure the cable is connected. If the B(+) circuit (generator output) (9) cable is loose anywhere in the circuit the B(+) sense circuit (10) will show high voltage. This condition causes the PCM (2) to shut down the generator field circuit (1). Because of this feature, pin 2 of the field connector is internally connected to the B(+) circuit (9).
| Refer to COMPONENT INDEX . |
Provides the battery temperature reading for the EVR circuitry to monitor.
| Refer to COMPONENT INDEX . |
As the energized rotor begins to rotate within the generator, the spinning magnetic field induces a current into the windings of the stator coil.
The Y type stator winding connections deliver the induced AC current to positive and negative diodes for rectification. From the diodes, rectified DC current is delivered to the vehicles electrical system through the generator, battery, and ground terminals.
Noise emitting from the generator may be caused by:
- Worn, loose or defective bearings
- Loose or defective drive pulley
- Incorrect, worn, damaged or miss-adjusted drive belt
- Loose mounting bolts
- Misaligned drive pulley
- Defective stator or diode
- Damaged internal fins
| Refer to COMPONENT INDEX . |
The IBS determines the battery temperature and provides this information to the BCM.
| Refer to COMPONENT INDEX . |
The PCM contains the EVR software and circuit.
The amount of direct current produced by the generator is controlled by EVR circuitry contained within the PCM. This circuitry is connected in series with the generators second rotor field terminal and its ground.
Voltage is regulated by cycling the battery positive path to control the strength of the rotor magnetic field. The EVR circuitry monitors system line voltage (B(+)) and battery temperature which is provided by the IBS. It then determines a target charging voltage. If sensed battery voltage is 0.5 volts or lower than the target voltage, the PCM grounds the field winding until sensed battery voltage is 0.5 volts above target voltage. A circuit in the PCM cycles the battery positive (high side) of the generator field up to 400 times per second (400Hz), but has the capability to ground the field control wire 100% of the time (full field) to achieve the target voltage. If the charging rate cannot be monitored (limp-in), a duty cycle of 25% is used by the PCM in order to have some generator output