engine JEEP YJ 1995 Service And Repair Manual

(4) Connect voltmeter to measure between the bat-
tery negative post and a good clean ground on the
engine block (Fig. 5). Rotate and hold ignition switch
in the START position. Observe voltmeter. If voltage
reads above 0.2 volt, correct poor contact at battery
negative cable attaching point. Repeat test. If read-
ing is still above 0.2 volt, replace battery negative ca-
ble.
(5) Connect positive lead of voltmeter to starter
housing. Connect negative lead of voltmeter to bat-
tery negative terminal (Fig. 6). Rotate and hold igni-
tion switch in the START position. Observe
voltmeter. If voltage reads above 0.2 volt, correct poor
starter to engine ground.
If resistance tests detect no feed circuit problems,
remove the starter and see Solenoid Test in this
group.
CONTROL CIRCUIT TESTS
The starter control circuit consists of:
²starter solenoid
²starter relay
²ignition switch
²park/neutral position switch (automatic transmis-
sion)²wiring harness and connections.
Test procedures for these components are as fol-
lows, and should be followed in the order described.
CAUTION: Before performing any test, unplug Auto
Shut-Down (ASD) relay from Power Distribution
Center (PDC) to prevent engine from starting.
SOLENOID TEST
Refer to Group 8B - Battery/Starter/Generator Ser-
vice for starter removal procedures.
(1) Disconnect solenoid field coil wire from field
coil terminal.
(2) Check for continuity between solenoid terminal
and field coil terminal with a continuity tester. There
should be continuity (Fig. 7).
(3) Check for continuity between solenoid terminal
and solenoid case. There should be continuity (Fig.
8).
(4) If there is continuity, solenoid is good. If there
is no continuity in either test, solenoid has an open
circuit and is faulty. Replace starter assembly.
(5) Connect solenoid field coil wire to field coil ter-
minal.
(6) Install starter as described in Group 8B - Bat-
tery/Starter/Generator Service.
RELAY TEST
The starter relay is in the Power Distribution Cen-
ter (PDC)(Figs. 9 or 10). Refer to the underside of the
PDC cover for relay location.
Fig. 5 Test Ground Circuit Resistance
Fig. 6 Test Starter Ground (Typical)
Fig. 7 Continuity Test Between Solenoid Terminal
and Field Coil Terminal
Fig. 8 Continuity Test Between Solenoid Terminal
and Solenoid Case
8A - 14 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

IGNITION SWITCH TEST
Refer to Group 8D - Ignition Systems for testing
and service of this component.
PARK/NEUTRAL POSITION SWITCH TEST
Refer to Group 21 - Transmission and Transfer
Case for testing and service of this component.
2.5L STARTER NOISE DIAGNOSIS
See Starter Noise Diagnosis chart. If the complaint
is similar to Conditions 1 and 2 in chart, correction
can be achieved by shimming starter according to the
following procedures:
Disconnect the battery negative cable to pre-
vent inadvertent starting of engine.
(1) If the complaint is similar to Condition 1, the
starter must be moved toward the flywheel/drive
plate ring gear by removing shims (Fig. 11).
Shim thickness is 0.381 mm (0.015 in.) and
shims may be stacked if required.
(2) If the complaint is similar to Condition 2, the
starter must be moved away from the flywheel/drive
plate ring gear. This is done by installing shim(s)
across both mounting pads. More than one shim may
be required.
This is generally a condition that causes bro-
ken flywheel/drive plate ring gear teeth or bro-
ken starter housings.
STARTER NOISE DIAGNOSIS
Fig. 11 Starter Shim
8A - 16 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

CHARGING SYSTEM
GENERAL INFORMATION
The charging system consists of:
²generator
²voltage regulator circuitry (within PCM)
²ignition switch
²battery
²generator warning lamp or voltmeter (depending
on vehicle equipment)
²wiring harness and connections.
Following is a general description of the major
charging system components. Refer to Group 8W -
Wiring Diagrams for complete circuit descriptions
and diagrams.
The charging system is turned on and off with the
ignition switch. When the ignition switch is turned to
the ON position, battery voltage is applied to the
generator rotor through one of the two field termi-
nals to produce a magnetic field. The generator is
driven by the engine through a serpentine belt and
pulley arrangement.
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 wye (Y) type stator winding connections de-
liver the induced AC current to 3 positive and 3 neg-
ative diodes for rectification. From the diodes,
rectified DC current is delivered to the vehicle elec-
trical system through the generator battery and
ground terminals.
The amount of DC current produced by the gener-
ator is controlled by the generator voltage regulator
(field control) circuitry, contained within the Power-
train Control Module (PCM)(Fig. 1). This circuitry is
connected in series with the second rotor field termi-
nal and ground.
Voltage is regulated by cycling the ground path to
control the strength of the rotor magnetic field. The
generator voltage regulator circuitry monitors system
line voltage and ambient temperature. It then com-
pensates and regulates generator current output ac-
cordingly.
The generator is serviced only as a complete as-
sembly. If the generator fails for any reason, the en-
tire assembly must be replaced. The generator
voltage regulator (field control) circuitry can be ser-
viced only by replacing the entire PCM.
All vehicles are equipped with On-Board Diagnos-
tics (OBD). All OBD-sensed systems, including the
generator voltage regulator (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 any failureit detects. See Using On-Board Diagnostic System in
this group for more information.
DIAGNOSIS
When operating normally, the indicator lamp on
models with the base instrument cluster will light
when the ignition switch is turned to the ON or
START position. After the engine starts, the indicator
lamp goes off. With the engine running, the charge
indicator lamp should light only when there is a
problem in the charging system (base cluster only).
On models with a voltmeter, when the ignition
switch is turned to the ON position, battery potential
will register on the meter. During engine cranking a
lower voltage will appear on the meter. With the en-
gine running, a voltage reading higher than the first
reading (ignition in ON) should register.
The following procedures may be used to diagnose
the charging system if:
²the indicator or voltmeter do not operate properly
²an undercharged or overcharged battery condition
occurs.
Remember that an undercharged battery is often
caused by:
Fig. 1 Charging System Components (Typical)
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 17

²accessories being left on with the engine not run-
ning
²a faulty or improperly adjusted switch that allows
a lamp to stay on (see Ignition-Off Draw, in this
group).
INSPECTION
(1) Inspect condition of battery cable terminals,
battery posts, connections at engine block, starter so-
lenoid and relay. They should be clean and tight. Re-
pair as required.
(2) Inspect all fuses in the fuseblock module and
Power Distribution Center (PDC) for tightness in re-
ceptacles. They should be properly installed and
tight. Repair or replace as required.
(3) Inspect the electrolyte level in the battery. If
cell caps are removable, add water if required. If cell
caps are not removable, replace battery if electrolyte
level is low.
(4) Inspect generator mounting bolts for tightness.
Replace or tighten bolts, if required. Refer to Group
8B - Battery/Starter/Generator Service for torque
specifications.
(5) Inspect generator drive belt condition and ten-
sion. Tighten or replace belt as required. Refer to
Belt Tension Specifications in Group 7 - Cooling Sys-
tem.
(6) Inspect connections at generator field, battery
output, and ground terminals. Also check ground con-
nection at engine. They should all be clean and tight.
Repair as required.
OUTPUT WIRE RESISTANCE TEST
This test will show the amount of voltage drop
across the generator output wire, from the generator
battery terminal to the battery positive post.
PREPARATION
(1) Before starting test make sure vehicle has a
fully-charged battery. See Battery in this group for
more information.
(2) Turn ignition switch to OFF.
(3) Disconnect negative cable from battery.
(4) Disconnect generator output wire from genera-
tor battery output terminal.
(5) Connect a 0-150 ampere scale DC ammeter
(Fig. 2). Install in series between generator battery
output terminal and disconnected generator output
wire. Connect positive lead to generator battery out-
put terminal and negative lead to disconnected gen-
erator output wire.
(6) Connect positive lead of a test voltmeter (range
0-18 volts minimum) to disconnected generator out-
put wire. Connect negative lead of test voltmeter to
battery positive cable at positive post.
(7) Connect one end of a jumper wire to ground
and with other end probe green K20 field wire at
back of generator (Fig. 2). This will generate a DTC.CAUTION: Do not connect green/orange A142 field
wire to ground. Refer to Group 8W - Wiring Dia-
grams for more information.
(8) Connect an engine tachometer, then connect
battery negative cable to battery.
(9) Connect a variable carbon pile rheostat be-
tween battery terminals. Be sure carbon pile is in
OPEN or OFF position before connecting leads. See
Load Test in this group for instructions.
TEST
(1) Start engine. Immediately after starting, re-
duce engine speed to idle.
(2) Adjust engine speed and carbon pile to main-
tain 20 amperes flowing in circuit. Observe voltmeter
reading. Voltmeter reading should not exceed 0.5
volts.
RESULTS
If a higher voltage drop is indicated, inspect, clean
and tighten all connections. This includes any con-
nection between generator battery output terminal
and battery positive post. A voltage drop test may be
performed at each connection to locate the connection
with excessive resistance. If resistance tests satisfac-
torily, reduce engine speed, turn OFF carbon pile and
turn OFF ignition switch.
(1) Disconnect negative cable from battery.
(2) Remove test ammeter, voltmeter, carbon pile,
and tachometer.
(3) Remove jumper wire.
(4) Connect generator output wire to generator
battery output terminal. Tighten nut to 8.561.5 Nzm
(75615 in. lbs.).
(5) Connect negative cable to battery.
(6) Use DRB scan tool to erase DTC.
CURRENT OUTPUT TEST
The generator current output test determines
whether generator can deliver its rated current out-
put.
PREPARATION
(1) Before starting test make sure vehicle has a
fully-charged battery. See Battery in this group for
more information.
(2) Disconnect negative cable from battery.
(3) Disconnect generator output wire at the gener-
ator battery output terminal.
(4) Connect a 0-150 ampere scale DC ammeter
(Fig. 3). Install in series between generator battery
output terminal and disconnected generator output
wire. Connect positive lead to generator battery out-
put terminal and negative lead to disconnected gen-
erator output wire.
8A - 18 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

(5) Connect positive lead of a test voltmeter (range
0-18 volts minimum) to generator battery output ter-
minal.
(6) Connect negative lead of test voltmeter to a
good ground.
(7) Connect an engine tachometer, then connect
battery negative cable to battery.
(8) Connect a variable carbon pile rheostat be-
tween battery terminals. Be sure carbon pile is in
OPEN or OFF position before connecting leads. See
Load Test in this group for instructions.
(9) Connect one end of a jumper wire to ground
and with other end probe green K20 field wire at
back of generator (Fig. 3). This will generate a DTC.
CAUTION: Do not connect green/orange A142 field
wire to ground. Refer to Group 8W - Wiring Dia-
grams for more information.TEST
(1) Start engine. Immediately after starting, re-
duce engine speed to idle.
(2) Adjust carbon pile and engine speed in incre-
ments until a speed of 1250 rpm and voltmeter read-
ing of 15 volts is obtained.
CAUTION: Do not allow voltage meter to read above
16 volts.
(3) The ammeter reading must be within limits
shown in Generator Output Voltage Specifications.
RESULTS
(1) If reading is less than specified and generator
output wire resistance is not excessive, generator
should be replaced. Refer to Group 8B - Battery/
Starter/Generator Service.
CHARGING SYSTEM DIAGNOSIS
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 19

(2) After current output test is completed, reduce
engine speed, turn OFF carbon pile and turn OFF ig-
nition switch.
(3) Disconnect negative cable from battery.
(4) Remove test ammeter, voltmeter, tachometer
and carbon pile.(5) Remove jumper wire (Fig. 3).
(6) Connect generator output wire to generator
battery output terminal. Tighten nut to 8.561.5 Nzm
(75615 in. lbs.).
(7) Connect negative cable to battery.
(8) Use DRB scan tool to erase DTC.
Fig. 2 Generator Output Wire Resistance Test (Typical)
8A - 20 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

USING ON-BOARD DIAGNOSTIC SYSTEM
GENERAL INFORMATION
The Powertrain Control Module (PCM) monitors
critical input and output circuits of the charging sys-
tem, making sure they are operational. A Diagnostic
Trouble Code (DTC) is assigned to each input and
output circuit monitored by the OBD system. Some
circuits are checked continuously and some are
checked only under certain conditions.
If the OBD system senses that a monitored circuit
is bad, it will put a DTC into electronic memory. The
DTC will stay in electronic memory as long as the
circuit continues to be bad. The PCM is programmed
to clear the memory after 50 engine starts, if the
problem does not occur again.
DIAGNOSTIC TROUBLE CODES
Diagnostic Trouble Codes (DTC) are two-digit num-
bers flashed on the malfunction indicator (Check En-
gine) lamp that identify which circuit is bad. A DTC
description can also be read using the DRB scan tool.
Refer to Group 14 - Fuel Systems for more informa-
tion.
A DTC does not identify which component in a cir-
cuit is bad. Thus, a DTC should be treated as a
symptom, not as the cause for the problem. In some
cases, because of the design of the diagnostic test
procedure, a DTC can be the reason for another DTCto be set. Therefore, it is important that the test pro-
cedures be followed in sequence, to understand what
caused a DTC to be set.
See Generator Diagnostic Trouble Code chart for
DTC's which apply to the charging system. Refer to
the Powertrain Diagnostic Procedures manual to di-
agnose an on-board diagnostic system trouble code.
RETRIEVING DIAGNOSTIC TROUBLE CODES
To start this function, cycle the ignition switch ON-
OFF-ON-OFF-ON within 5 seconds. This will cause
any DTC stored in the PCM memory to be displayed.
The malfunction indicator (Check Engine) lamp will
display a DTC by flashing on and off. There is a
short pause between flashes and a longer pause be-
tween digits. All DTC's displayed are two-digit num-
bers, with a four-second pause between codes.
An example of a DTC is as follows:
(1) Lamp on for 2 seconds, then turns off.
(2) Lamp flashes 4 times pauses and then flashes 1
time.
(3) Lamp pauses for 4 seconds, flashes 4 times,
pauses, then flashes 7 times.
The two DTC's are 41 and 47. Any number of
DTC's can be displayed, as long as they are in mem-
ory. The lamp will flash until all stored DTC's are
displayed (55 = end of test).
GENERATOR DIAGNOSTIC TROUBLE CODE
8A - 22 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

CAUTION: Be certain that battery cables are con-
nected to the correct battery terminals. Reverse po-
larity can damage electrical components.
(12) Place oiled felt washer on battery positive ter-
minal post.
(13) Install and tighten battery positive cable ter-
minal clamp. Then install and tighten negative cableterminal clamp. Both cable clamp bolts require
torque of 8.5 Nzm (75 in. lbs.).
(14) Apply a thin coating of petroleum jelly or
chassis grease to cable terminals and battery posts.
STARTER AND STARTER RELAY
GENERAL INFORMATION
This section covers starter and starter relay service
procedures only. For diagnostic procedures, refer to
Group 8A - Battery/Starting/Charging Systems Diag-
nostics. Service procedures for other starting system
components can be found as follows:
²battery - see Battery, in this group
²ignition switch - refer to Group 8D - Ignition Sys-
tems
²park/neutral position switch (automatic transmis-
sion) - refer to Group 21 - Transmission and Transfer
Case
²wiring harness and connectors - refer to Group 8W
- Wiring Diagrams.
STARTER
The starter motor incorporates several features to
create a reliable, efficient, compact and lightweight
unit. A planetary gear system (intermediate trans-
mission) is used between the electric motor and pin-
ion gear. This feature makes it possible to reduce the
dimensions of the starter. At the same time, it allows
higher armature rotational speed and delivers in-
creased torque through the pinion gear to the fly-
wheel or drive plate ring gear.
The use of a permanent magnet field also reduces
starter size and weight. This field consists of six
high-strength permanent magnets. The magnets are
aligned according to their polarity and are perma-
nently fixed in the starter field frame.
The starter motors for all engines are activated by
a solenoid mounted to the overrunning clutch hous-
ing. However, the starter motor/solenoid are serviced
only as a complete assembly. If either component
fails, the entire assembly must be replaced.
This unit is highly sensitive to hammering, shocks
and external pressure.
CAUTION: The starter motor MUST NOT BE
CLAMPED in a vise by the starter field frame. Doing
so may damage the magnets. It may be clamped by
the mounting flange ONLY.CAUTION: Do not connect starter motor incorrectly
when tests are being performed. The permanent
magnets may be damaged and rendered unservice-
able.
STARTER RELAY
The starter relay is an International Standards Or-
ganization (ISO) type relay, and is located in the
Power Distribution Center (PDC). Refer to underside
of PDC cover for relay location.
STARTER REMOVE/INSTALLÐ2.5L
XJ MODELS
(1) Disconnect battery negative cable.
(2) Remove exhaust clamp from bracket (Fig. 11).
(3) Remove nut and bolt from forward end of brace
rod (automatic transmission only).
Fig. 11 Exhaust Clamp and Brace Remove (XJÐ
2.5L)
8B - 4 BATTERY/STARTER/GENERATOR SERVICEJ

STARTER RELAY REMOVE/INSTALL
(1) Disconnect battery negative cable.
(2) Remove starter relay by unplugging unit from
PDC (Fig. 15 or 16).(3) Install starter relay by aligning relay terminals
with cavities in PDC and plugging relay in.
(4) Connect negative cable to battery.
(5) Test relay operation.
GENERATOR
GENERAL INFORMATION
This section covers generator service procedures
only. For generator or charging system diagnosis, re-
fer to Group 8A - Battery/Starting/Charging Systems
Diagnostics.
The generator is belt-driven by the engine. All en-
gines use serpentine drive. The generator is serviced
only as a complete assembly. If the generator fails for
any reason, the entire assembly must be replaced.
Two generator output ratings are available, de-
pending upon optional equipment. Be certain that
the replacement generator has the same output rat-
ing as the original unit. Refer to Group 8A - Battery/
Starting/Charging Systems Diagnostics and see
Specifications.
The generator field control (voltage regulator) cir-
cuitry is internal to the Powertrain Control Module
(PCM). If faulty, the entire PCM must be replaced.
Refer to Group 14 - Fuel System for PCM service
procedure.
GENERATOR REMOVE/INSTALLÐLEFT-HAND
DRIVE
WARNING: DISCONNECT NEGATIVE CABLE FROM
BATTERY BEFORE REMOVING BATTERY OUTPUT
WIRE FROM GENERATOR. FAILURE TO DO SO
CAN RESULT IN INJURY.
ALL WITH 2.5L AND YJ WITH 4.0L
(1) Disconnect battery negative cable.
(2) Remove generator drive belt. Refer to Group 7 -
Cooling System for procedure.
(3) Remove generator battery output terminal nut,
2 field terminal nuts, ground and harness holddown
nuts (Fig. 17). Remove wire connector assembly.
(4) Remove 2 generator mounting bolts and remove
generator from vehicle.
(5) Reverse removal procedure to install. Torque
generator hardware as shown in Specifications.
CAUTION: Never force a belt over a pulley rim us-
ing a screwdriver. The synthetic fiber of the belt can
be damaged.
Fig. 15 Power Distribution CenterÐXJFig. 16 Power Distribution CenterÐYJ
8B - 6 BATTERY/STARTER/GENERATOR SERVICEJ

CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. The
water pump will be rotating in the wrong direction if
the belt is installed incorrectly, causing the engine
to overheat. Refer to the belt routing label in engine
compartment, or refer to Belt Schematics in Group
7 - Cooling System.
XJ WITH 4.0L
(1) Disconnect battery negative cable.
(2) Remove generator drive belt. Refer to Group 7 -
Cooling System for procedure.
(3) Raise and support vehicle.
(4) Remove generator battery output terminal nut,
2 field terminal nuts, ground and harness holddown
nuts (Fig. 17). Remove wire connector assembly.
(5) Remove 2 generator mounting bolts and remove
generator from vehicle.
(6) Reverse removal procedure to install. Torque
generator hardware as shown in Specifications.
CAUTION: Never force a belt over a pulley rim us-
ing a screwdriver. The synthetic fiber of the belt can
be damaged.
CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. The
water pump will be rotating in the wrong direction ifthe belt is installed incorrectly, causing the engine
to overheat. Refer to the belt routing label in engine
compartment, or refer to Belt Schematics in Group
7 - Cooling System.
GENERATOR REMOVE/INSTALLÐRIGHT-HAND
DRIVE
WARNING: DISCONNECT NEGATIVE CABLE FROM
BATTERY BEFORE REMOVING BATTERY OUTPUT
WIRE FROM GENERATOR. FAILURE TO DO SO
CAN RESULT IN INJURY.
(1) Disconnect battery negative cable.
(2) Remove 2 screws holding electric cooling fan
(Fig. 18).
(3) Unplug electric cooling fan wiring connector
and pull fan unit up and out of vehicle.
(4) Remove generator drive belt. Refer to Group 7 -
Cooling System for procedure.
(5) Remove generator mounting bolts.
(6) Position generator to gain access to all of the
wire connectors. Remove generator battery output
terminal nut, 2 field terminal nuts, ground and har-
ness holddown nuts (Fig. 17). Remove wire connector
assembly.
(7) Remove generator from vehicle.
(8) Reverse removal procedure to install. Torque
generator hardware as shown in Specifications.
Fig. 17 Remove/Install Generator Connector
Fig. 18 Electric Cooling Fan Remove/Install
JBATTERY/STARTER/GENERATOR SERVICE 8B - 7