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. When the ASD relay is on, voltage is supplied to the ASD relay sense circuit at the
PCM (ECM Diesel). This voltage is connected through the PCM (ECM Diesel) and supplied to one of the generator
field terminals (Gen. Source +) at the back of the generator.

The amount of direct current produced by the generator is controlled by the EVR (field control) circuitry contained
within the PCM (ECM Diesel). This circuitry is connected in series with the second rotor field terminal and ground.

A battery temperature sensor, located in the battery tray housing, is used to sense battery temperature. This tem-
perature data, along with data from monitored line voltage, is used by the PCM (ECM Diesel) to vary the battery
charging rate. This is done by cycling the ground path to control the strength of the rotor magnetic field. The PCM
then compensates and regulates generator current output accordingly.

All vehicles are equipped with On-Board Diagnostics (OBD). All OBD-sensed systems, including EVR (field control)
circuitry, are monitored by the PCM (ECM Diesel). Each monitored circuit is assigned a Diagnostic Trouble Code
(DTC). The PCM will store a DTC in electronic memory for certain failures it detects.

The Check Gauges Lamp (if equipped) monitors: charging system voltage, engine coolant temperature and
engine oil pressure. If an extreme condition is indicated, the lamp will be illuminated. This is done as reminder to
check the three gauges. The signal to activate the lamp is sent via the CCD bus circuits. The lamp is located on the
instrument panel. Refer to 8, Instrument Panel and Gauges for additional information.

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CHARGING

DR/DH

DIAGNOSIS AND TESTING - CHARGING SYSTEM

The following procedures may be used to diagnose the charging system if:

•

the check gauges lamp (if equipped) is illuminated with the engine running

•

the voltmeter (if equipped) does not register properly

•

an undercharged or overcharged battery condition occurs.

Remember that an undercharged battery is often caused by:

•

accessories being left on with the engine not running

•

a faulty or improperly adjusted switch that allows a lamp to stay on. Refer to Ignition-Off Draw Test in 8, Bat-
tery for more information.

INSPECTION

The PCM (Powertrain Control Module), or ECM (Diesel) monitors critical input and output circuits of the charging
system, making sure they are operational. A Diagnostic Trouble Code (DTC) is assigned to each input and output
circuit monitored by the On-Board Diagnostic (OBD) system. Some charging system circuits are checked continu-
ously, and some are checked only under certain conditions.

Refer to Diagnostic Trouble Codes in; Powertrain Control Module; Electronic Control Modules for more DTC infor-
mation. This will include a complete list of DTC’s including DTC’s for the charging system.

To perform a complete test of the charging system, refer to the appropriate Powertrain Diagnostic Procedures ser-
vice manual and the DRB

scan tool. Perform the following inspections before attaching the scan tool.

1. Inspect the battery condition. Refer to 8, Battery for procedures.

2. Inspect condition of battery cable terminals, battery posts, connections at engine block, starter solenoid and

relay. They should be clean and tight. Repair as required.

3. Inspect all fuses in both the fuseblock and Power Distribution Center (PDC) for tightness in receptacles. They

should be properly installed and tight. Repair or replace as required.

4. Inspect generator mounting bolts for tightness. Replace or tighten bolts if required. Refer to the Generator

Removal/Installation section of this group for torque specifications.

5. Inspect generator drive belt condition and tension. Tighten or replace belt as required. Refer to Belt Tension

Specifications in 7, Cooling System.

Inspect automatic belt tensioner (if equipped). Refer to 7, Cooling System for information.

7. Inspect generator electrical connections at generator field, battery output, and ground terminal (if equipped). Also

check generator ground wire connection at engine (if equipped). They should all be clean and tight. Repair as
required.

SPECIFICATIONS

GENERATOR RATINGS

TYPE

PART NUMBER

RATED SAE AMPS

ENGINES

DENSO

56029700AA

136

3.7L / 4.7L

BOSCH

56041120AC

136

3.7L / 4.7L

DENSO

56028696AA

136

5.7L Gas/5.9L Diesel

BOSCH

56028699AA

136

5.7L Gas/5.9L Diesel

DR/DH

CHARGING

8F - 41

TORQUE - GENERATOR / CHARGING SYSTEM

DESCRIPTION

N·m

Ft. Lbs.

In. Lbs.

Generator Mounting Bolts

- 5.7L

Generator Support Bracket

Bolt/Nuts - 5.7L

Generator Upper Mounting

Bolt - 5.9L Diesel Engine

Generator Vertical

Mounting Bolt - 3.7L / 4.7L

Engines

Generator (long)

Horizontal Mounting Bolt -

3.7L / 4.7L Engines

Generator (short)

Horizontal Mounting Bolt -

3.7L / 4.7L Engines

Generator Upper & Lower

Mounting Bolt - 8.3L

Engine

Generator B+ Output

Cable Terminal Nut

108

BATTERY TEMPERATURE SENSOR

DESCRIPTION

The Battery Temperature Sensor (BTS) is attached to the battery tray located under the battery.

OPERATION

The BTS is used to determine the battery temperature and control battery charging rate. This temperature data,
along with data from monitored line voltage, is used by the PCM (ECM Diesel) to vary the battery charging rate.
System voltage will be higher at colder temperatures and is gradually reduced at warmer temperatures.

The PCM sends 5 volts to the sensor and is grounded through the sensor return line. As temperature increases,
resistance in the sensor decreases and the detection voltage at the PCM increases.

The BTS is also used for OBD II diagnostics. Certain faults and OBD II monitors are either enabled or disabled,
depending upon BTS input (for example, disable purge and enable Leak Detection Pump (LDP) and O2 sensor
heater tests). Most OBD II monitors are disabled below 20°F.

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CHARGING

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REMOVAL

The battery temperature sensor (1) is located under
the vehicle battery and is attached (snapped into) a
mounting hole on battery tray (4).

1. Remove battery. Refer to 8, Battery for procedures.

2. Pry sensor (1) straight up from battery tray mount-

ing hole to gain access to electrical connector (3).

3. Disconnect sensor from engine wire harness elec-

trical connector.

INSTALLATION

NOTE: The battery temperature sensor (1) is located under the vehicle battery and is attached (snapped
into) a mounting hole on battery tray (4).

1. Pull electrical connector (3) up through mounting

hole in top of battery tray.

2. Connect sensor.

3. Snap sensor into battery tray.

4. Install battery. Refer to 8, Battery for procedures.

DR/DH

CHARGING

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