CHARGING
DESCRIPTION - CHARGING SYSTEM
The charging system consists of:
•
Generator
•
Decoupler Pulley (If equipped)
•
Electronic Voltage Regulator (EVR) circuitry within the Powertrain Control Module (PCM)
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Ignition switch (refer to the Ignition System section for information)
•
Battery (refer to the Battery section for information)
•
Ambient Air Temperature (If equipped)
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Inlet Air Temperature (calculated battery temperature)(If equipped)
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Voltmeter (refer to the Instrument Cluster section for information if equipped)
•
Wiring harness and connections (refer to the Wiring section for information)
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Accessory drive belt (refer to the Cooling section for more information)
•
Battery Temperature sensor (if equipped)
OPERATION - CHARGING SYSTEM
The charging system is turned on and off with the ignition switch. The system is on when the engine is running and
the ASD relay is energized. The ASD relay is energized when the PCM grounds the ASD control circuit. This voltage
is connected through the PCM or IPM (intelligent power module) (if equipped) and supplied to one of the generator
field terminals (Gen. Source +) at the back of the generator.
The generator is driven by the engine through a serpentine belt and pulley or decoupler pulley arrangement.
The amount of DC current produced by the generator is controlled by the EVR (field control) circuitry contained
within the PCM. This circuitry is connected in series with the second rotor field terminal and ground.
An Ambient air temperature sensor is mounted on the bumper used to calculate the temperature near the battery.
This temperature data, along with data from monitored line voltage (battery voltage sense circuit), is used by the
PCM to vary the battery charging rate. This is done by cycling the feed path to control the strength of the rotor
magnetic field. The PCM then compensates and regulates generator current output accordingly to maintain system
voltage at the targeted system voltage based on battery temperature.
All vehicles are equipped with On-Board Diagnostics (OBD). All OBD-sensed systems, including EVR (field control)
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 and illuminate the (MIL) lamp. Refer to On-Board
Diagnostics in the Electronic Control Modules (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/
POWERTRAIN CONTROL MODULE - DESCRIPTION) section for more DTC information.
The Charging system “Battery” light indicates problems with the charging system (voltage too high/low, generator
failure, etc.). If an extreme condition is indicated, the lamp will be illuminated. The signal to activate the lamp is sent
via the PCI bus circuits. The lamp is located on the instrument panel. Refer to the Instrument Cluster section for
additional information.
The PCM uses the inlet air temperature sensor or ambient temperature sensor to control the charge system voltage.
This temperature, along with data from monitored line voltage, is used by the PCM to vary the battery charging rate.
The system voltage is higher at cold temperatures and is gradually reduced as the calculated battery temperature
increases.
The ambient temperature sensor is used to control the battery voltage based upon ambient temperature (approxi-
mation of battery temperature). The PCM maintains the optimal output of the generator by monitoring battery volt-
age and controlling it to a range of 13.5 - 14.7 volts based on battery temperature.
8F - 42
CHARGING
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