Charging System - Jeep Wrangler 1999 Electronic Service Manual

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DESCRIPTION AND OPERATION
BATTERY TEMPERATURE SENSOR . . . . . . . . . . 2
CHARGING SYSTEM OPERATION . . . . . . . . . . . 1
ELECTRONIC VOLTAGE REGULATOR . . . . . . . . . 2
GENERATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
DIAGNOSIS AND TESTING
BATTERY TEMPERATURE SENSOR . . . . . . . . . . 2

CHARGING SYSTEM . . . . . . . . . . . . . . . . . . . . . . 2

DESCRIPTION AND OPERATION
CHARGING SYSTEM OPERATION
The charging system consists of:
• Generator
• Electronic Voltage Regulator (EVR) circuitry
within the Powertrain Control Module (PCM)
• Ignition switch (refer to Group 8D, Ignition Sys-
tem for information)
• Battery (refer to Group 8A, Battery for informa-
tion)
• Battery temperature sensor
• Generator Lamp (if equipped)
• Check Gauges Lamp (if equipped)
• Voltmeter (refer to Group 8E, Instrument Panel
and Gauges for information)
• Wiring harness and connections (refer to Group
8W, Wiring for information)
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. This voltage is connected
through the PCM and supplied to one of the genera-
tor field terminals (Gen. Source +) at the back of the
generator.
The amount of DC current produced by the gener-
ator is controlled by the EVR (field control) circuitry
contained within the PCM. This circuitry is con-
nected in series with the second rotor field terminal
and ground.
A battery temperature sensor, located in the bat-
tery tray housing, is used to sense battery tempera-
ture. This temperature data, along with data from
monitored line voltage, is used by the PCM to vary
the battery charging rate. This is done by cycling the
CHARGING SYSTEM
CONTENTS
page
ON-BOARD DIAGNOSTIC TEST FOR
CHARGING SYSTEM . . . . . . . . . . . . . . . . . . . . 3
REMOVAL AND INSTALLATION
BATTERY TEMPERATURE SENSOR . . . . . . . . . . 3
GENERATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
SPECIFICATIONS
GENERATOR RATINGS . . . . . . . . . . . . . . . . . . . . 5
TORQUE CHART . . . . . . . . . . . . . . . . . . . . . . . . . 5
ground path to control the strength of the rotor mag-
netic field. The PCM then compensates and regulates
generator current output accordingly.
All vehicles are equipped with On-Board Diagnos-
tics (OBD). All OBD-sensed systems, including EVR
(field control) circuitry, are monitored by the PCM.
Each monitored circuit is assigned a Diagnostic Trou-
ble Code (DTC). The PCM will store a DTC in elec-
tronic memory for certain failures it detects. Refer to
On-Board Diagnostics in Group 25, Emission Control
System for more DTC information.
The Check Gauges Lamp (if equipped) monitors:
charging system voltage, engine coolant tempera-
ture 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 sig-
nal to activate the lamp is sent via the CCD bus cir-
cuits. The lamp is located on the instrument panel.
Refer to Group 8E, Instrument Panel and Gauges for
additional information.
GENERATOR
The generator is belt-driven by the engine using a
serpentine type drive belt. It is serviced only as a
complete assembly. If the generator fails for any rea-
son, the entire assembly must be replaced.
As the energized rotor begins to rotate within the
generator, the spinning magnetic field induces a cur-
rent into the windings of the stator coil. Once the
generator begins producing sufficient current, it also
provides the current needed to energize the rotor.
The Y type stator winding connections deliver the
induced AC current to 3 positive and 3 negative
diodes for rectification. From the diodes, rectified DC
current is delivered to the vehicle electrical system
through the generator battery terminal.
CHARGING SYSTEM 8C - 1
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