exj 8b, JEEP Manuals, Electronic Service Manual (jeep cherokee xj do 2000)
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XJ
STARTING SYSTEMS
8B - 1
STARTING SYSTEMS
TABLE OF CONTENTS
page
page
DESCRIPTION AND OPERATION
DIAGNOSIS AND TESTING
REMOVAL AND INSTALLATION
CLEANING AND INSPECTION
SPECIFICATIONS
DESCRIPTION AND OPERATION
Refer to
Battery
in the index of this service manual
for the location of more information on the battery.
²
STARTING SYSTEM
The battery cables connect the battery to the
electrical system of the vehicle and to the starting
system. Refer to
Battery Cables
in the index of this
service manual for the location of more information
on the battery cables.
The starting system low-amperage control circuit
includes the ignition switch, the clutch pedal position
switch (manual transmission), the park/neutral posi-
tion switch (automatic transmission), the starter
relay, the electromagnetic windings of the starter
solenoid, and the wire harnesses that connect these
components. The following starting system control
circuit
DESCRIPTION
An electrically operated engine starting system is
standard factory-installed equipment on this model.
The starting system is designed to provide the vehi-
cle operator with a convenient, efficient and reliable
means of cranking and starting the internal combus-
tion engine used to power the vehicle and all of its
accessory systems. The starting system includes the
following major components:
²
Battery
components
are
covered
in
more
detail
in
²
Battery cables
other areas of this service manual:
²
²
Clutch pedal position switch (manual transmis-
The ignition switch is mounted on the bottom of
the steering column and actuates the starting system
when a properly coded ignition key is inserted in the
ignition lock cylinder on the right side of the steering
column and turned to the spring-loaded momentary
Start position. Refer to
Ignition Switch and Key
Lock Cylinder
in the index of this service manual
for the location of more information on the ignition
switch.
²
sion)
²
Ignition switch
Park/neutral position switch (automatic trans-
mission)
²
²
Starter
motor
(including
the
integral
starter
solenoid)
²
Starter relay.
The starting system consists of two separate cir-
cuits. A high-amperage feed circuit that feeds the
starter motor between 150 and 350 amperes of bat-
tery current, and a low-amperage control circuit that
operates on less than 20 amperes of battery current.
The starting system high-amperage feed circuit
includes the battery, the battery cables, the contact
disc portion of the starter solenoid, and the starter
motor. The following starting system feed circuit
components are covered in more detail in other areas
of this service manual:
²
The clutch pedal position switch is integral to
the master cylinder of the clutch hydraulic linkage
assembly on models equipped with a manual trans-
mission. Refer to
Clutch Hydraulic Linkage
in the
index of this service manual for the location of more
information on the clutch pedal position switch.
²
On models with the 2.5L engine, the park/neu-
tral position switch is threaded into the left side of
the automatic transmission case and has a spring-
loaded plunger that is actuated by a cam integral to
the gearshift mechanism within the transmission.
The back up lamp switch is also integral to the park/
neutral position switch. On models with the 4.0L
The battery is located in the passenger side
front corner of the engine compartment, near the
upper radiator crossmember and provides the electri-
cal current needed to operate the starting system.
 8B - 2
STARTING SYSTEMS
XJ
DESCRIPTION AND OPERATION (Continued)
engine, the park/neutral position switch is mounted
on the right side of the automatic transmission case.
The switch is indexed to and driven by the transmis-
sion manual valve shaft. Refer to
Park/Neutral
Position Switch
in the index of this service manual
for the location of more information on either version
of the park/neutral position switch.
Following are general descriptions of the starter
relay and the starter motor. See the owner’s manual
in the vehicle glove box for more information on the
features, use and operation of the starting system.
Refer to
Starting System
in the index of this ser-
vice manual for the location of complete wiring dia-
grams for the starting system.
by engaging the starter pinion gear with the starter
ring gear. Once the engine starts, the ignition switch
key is released by the vehicle operator. When the
ignition switch key is released, the switch automati-
cally returns to the On position, which de-energizes
the starting system.
STARTER MOTOR
DESCRIPTION
NOTE: This group covers both Left-Hand Drive
(LHD) and Right-Hand Drive (RHD) versions of this
model. Whenever required and feasible, the RHD
versions of affected vehicle components have been
constructed as mirror-image of the LHD versions.
While most of the illustrations used in this group
represent only the LHD version, the diagnostic and
service procedures outlined can generally be
applied to either version. Exceptions to this rule
have been clearly identified as LHD or RHD, if a
special illustration or procedure is required.
Fig. 1 Starter Motors
1 – STARTER SOLENOID
OPERATION
If the vehicle is equipped with a manual transmis-
sion, the clutch pedal position switch is installed in
series between the ignition switch and the coil bat-
tery terminal of the starter relay. This normally open
switch prevents the starter relay from being ener-
gized when the ignition switch is turned to the
momentary Start position, unless the clutch pedal is
fully depressed. This feature prevents starter motor
operation while the clutch disc and the flywheel are
engaged. The starter relay coil ground terminal is
always grounded on vehicles with a manual trans-
mission.
If the vehicle is equipped with an automatic trans-
mission, battery voltage is supplied through the low-
amperage control circuit to the coil battery terminal
of the starter relay when the ignition switch is
turned to the momentary Start position. The park/
neutral position switch is installed in series between
the starter relay coil ground terminal and ground.
This normally open switch prevents the starter relay
from
The starter motors used for both the 2.5L and the
4.0L engines available in this model are not inter-
changeable (Fig. 1). However, each of these starter
motors incorporates several of the same features to
create a reliable, efficient, compact, lightweight and
powerful unit. Both starters feature high torque
direct current electric motors. Inside both starter
motors the commutator of the rotating motor arma-
ture is contacted by four brushes. The starter motor
for the 2.5L engine is driven by four permanent mag-
net field poles, while the starter motor for the 4.0L
engine is driven by four electromagnetic field coils
wound around four pole shoes. The 2.5L starter
motor is rated at 1.2 kilowatts (about 1.6 horse-
power) output at 12 volts, while the 4.0L starter
motor
is
rated
at
1.4
kilowatts
(about
1.9
horse-
power) output at 12 volts.
These starter motors are equipped with a plane-
tary gear reduction (intermediate transmission) sys-
tem. The planetary gear reduction system consists of
a gear that is integral to the output end of the elec-
tric motor armature shaft that is in continual
engagement with a larger gear that fits on a spline
on the input end of the starter pinion gear shaft.
This feature makes it possible to reduce the dimen-
sions
being
energized
and
the
starter
motor
from
operating
unless
the
automatic
transmission
gear
selector is in the Neutral or Park positions.
When the starter relay coil windings are energized,
the relay directs battery current to the starter sole-
noid coil windings. When the starter solenoid coil
windings are energized, the solenoid directs battery
current to the starter motor, which cranks the engine
of
the
starter. At
the
same
time,
it
allows
higher
armature
rotational
speed
and
delivers
increased
torque
through
the
starter
pinion
gear.
 XJ
STARTING SYSTEMS
8B - 3
DESCRIPTION AND OPERATION (Continued)
STARTER RELAY
Both starter motors use an overrunning clutch and
starter pinion gear unit to engage and drive the
starter ring gear, which is integral to the flywheel
(manual transmission) or torque converter drive
plate (automatic transmission) mounted on the rear
crankshaft flange. Shims are available and can be
used to adjust the 2.5L starter motor mounting posi-
tion to correct for improper starter pinion gear to
starter ring gear engagement.
The starter motors for both engines are activated
by an integral heavy duty starter solenoid switch
mounted to the overrunning clutch housing. This
electromechanical switch connects and disconnects
the feed of battery current to the starter motor
through a movable contact on one end of the solenoid
core or plunger. At the same time, the solenoid
plunger actuates a shift fork that engages and disen-
gages the starter pinion gear with a starter ring
gear. The starter solenoid has two electromagnetic
windings or coils, a pull-in coil and a hold-in coil. The
pull-in coil requires more battery current and pro-
duces
DESCRIPTION
TERMINAL LEGEND
NUMBER
IDENTIFICATION
30
COMMON FEED
85
COIL GROUND
86
COIL BATTERY
87
NORMALLY OPEN
a
stronger
electromagnetic
field
than
the
hold-in coil.
Both starter motors are serviced only as a unit
with their starter solenoids, and cannot be repaired.
If either component is faulty or damaged, the entire
starter
87A
NORMALLY CLOSED
Fig. 2 Starter Relay
The starter relay (Fig. 2) is an electromechanical
device that switches battery current to the pull-in
coil of the starter solenoid when the ignition switch
is turned to the Start position. The starter relay is
located in the Power Distribution Center (PDC), in
the engine compartment. See the fuse and relay lay-
out label affixed to the inside surface of the PDC
cover for starter relay identification and location.
The starter relay is a International Standards
Organization (ISO) relay. Relays conforming to the
ISO specifications have common physical dimensions,
current capacities, terminal patterns, and terminal
functions.
The starter relay cannot be repaired or adjusted
and, if faulty or damaged, it must be replaced.
motor
and
starter
solenoid
unit
must
be
replaced.
OPERATION
When the starter solenoid pull-in coil windings are
energized the solenoid plunger is drawn into the elec-
tromagnetic coil. The solenoid plunger pulls the shift
lever in the starter motor. This engages the starter
overrunning clutch and pinion gear with the starter
ring gear on the manual transmission flywheel or on
the automatic transmission torque converter drive
plate. As the solenoid plunger reaches the end of its
travel, it moves the solenoid contact disc to complete
the high-amperage starter feed circuit and energizes
the solenoid hold-in coil windings. Battery current
now flows between the solenoid battery terminal and
the starter field terminal, energizing the starter and
cranking the engine.
Once the engine starts, the overrunning clutch pro-
tects the starter motor from damage by allowing the
starter pinion gear to spin faster than the pinion
shaft. When the solenoid plunger hold-in coil is de-
energized, the solenoid plunger return spring returns
the plunger to its relaxed position. This causes the
solenoid contact disc to open the starter feed circuit,
and the shift lever to disengage the overrunning
clutch and pinion gear unit from the starter ring
gear.
OPERATION
The ISO relay consists of an electromagnetic coil, a
resistor or diode, and three (two fixed and one movable)
electrical contacts. The movable (common feed) relay
contact is held against one of the fixed contacts (nor-
mally closed) by spring pressure. When the electromag-
netic coil is energized, it draws the movable contact
away from the normally closed fixed contact, and holds
it against the other (normally open) fixed contact.
When the electromagnetic coil is de-energized,
spring pressure returns the movable contact to the
normally closed position. The resistor or diode is con-
nected in parallel with the electromagnetic coil in the
relay, and helps to dissipate voltage spikes that are
produced when the coil is de-energized.
 8B - 4
STARTING SYSTEMS
XJ
DIAGNOSIS AND TESTING
The diagnostic procedures used for the battery,
starting system and charging system include the
most basic conventional diagnostic methods, to the
more sophisticated On-Board Diagnostics (OBD) built
into the Powertrain Control Module (PCM). Use of an
induction-type milliampere ammeter, a volt/ohmme-
ter, a battery charger, a carbon pile rheostat (load
tester) and a 12-volt test lamp may be required. All
OBD-sensed systems 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 any failure it detects. Refer to
Charging System, On-Board Diagnostic Test
in
the index of this service manual for the location of
the proper on-board diagnostic test procedures.
STARTING SYSTEM
DIAGNOSIS
The battery, starting system and charging system
in the vehicle operate with one another, and must be
tested as a complete system. In order for the engine
to start and the battery to charge properly, all of the
components that are used in these systems must per-
form within specifications. The service information
for these systems has been separated within this ser-
vice manual to make it easier to locate the specific
information you are seeking. However, when
attempting to diagnose any of these systems, it is
important that you keep their interdependency in
mind.
Starting System Diagnosis
Condition
Possible Cause
Correction
Starter fails to operate.
1. Battery discharged or
faulty.
2. Starting circuit wiring
faulty.
3. Starter relay faulty.
4. Ignition switch faulty.
5. Clutch pedal position
switch faulty.
6. Park/Neutral position
switch faulty or
misadjusted.
7. Starter solenoid faulty.
8. Starter motor faulty.
1. Refer to Battery in the index of this service manual for
the location of the proper battery diagnosis and testing
procedures. Replace the faulty battery, as required.
2. Refer to Starting System in the index of this service
manual for the location of complete starting system wiring
diagrams. Test and repair the faulty starter feed and/or
control circuits, as required.
3. Refer to Starter Relay in the index of this service
manual for the location ofr the proper starter relay
diagnosis and testing procedures. Replace the faulty
starter relay, as required.
4. Refer to Ignition Switch and Key Lock Cylinder in the
index of this service manual for the location of the proper
ignition switch diagnosis and testing procedures. Replace
the faulty ignition switch, as required.
5. Refer to Clutch Pedal Position Switch in the index of
this service manual for the location of the proper clutch
pedal position switch diagnosis and testing procedures.
Replace the faulty clutch hydraulic linkage unit, as
required.
6. Refer to Park/Neutral Position Switch in the index of
this service manual for the location of the proper
park/neutral position switch diagnosis and testing
procedures. Replace the faulty park/neutral position
switch, as required.
7. Refer to Starter Motor in the index of this service
manual for the location of the proper starter solenoid
diagnosis and testing procedures. Replace the faulty
starter motor, as required.
8. Refer to Starter Motor in the index of this service
manual for the location of the proper starter motor
diagnosis and testing procedures. Replace the faulty
starter motor, as required.
 XJ
STARTING SYSTEMS
8B - 5
DIAGNOSIS AND TESTING (Continued)
Starting System Diagnosis
Condition
Possible Cause
Correction
Starter engages, fails to
turn engine.
1. Battery discharged or
faulty.
2. Starting circuit wiring
faulty.
3. Starter motor faulty.
4. Engine seized.
1. Refer to Battery in the index of this service manual for
the location of the proper battery diagnosis and testing
procedures. Replace the faulty battery, as required.
2. Refer to Starting System in the index of this service
manual for the location of complete starting system wiring
diagrams. Test and repair the faulty starter feed and/or
control circuits, as required.
3. Refer to Starter Motor in the index of this service
manual for the location of the proper starter motor
diagnosis and testing procedures. Replace the faulty
starter motor, as required.
4. Refer to Engine Diagnosis in the index of this service
manual for the location of the proper engine diagnosis
and testing procedures. Repair or replace the faulty
engine, as required.
Starter engages, spins
out before engine starts.
1. Starter ring gear faulty.
2. Starter motor faulty.
1. Refer to Starter Motor in the index of this service
manual for the location of the proper starter motor
removal and installation procedures. Remove the starter
motor to inspect the starter ring gear. Replace the faulty
starter ring gear, as required.
2. Refer to Starter Motor in the index of this service
manual for the location of the proper starter motor
diagnosis and testing procedures. Replace the faulty
starter motor, as required.
Starter does not
disengage.
1. Starter motor
improperly installed.
2. Starter relay faulty.
3. Ignition switch faulty.
4. Starter motor faulty.
1. Refer to Starter Motor in the index of this service
manual for the location of the proper starter motor
installation procedures. Tighten the starter motor
mounting hardware to the correct tightness specifications,
as required.
2. Refer to Starter Relay in the index of this service
manual for the location of the proper starter relay
diagnosis and testing procedures. Replace the faulty
starter relay, as required.
3. Refer to Ignition Switch and Key Lock Cylinder in the
index of this service manual for the location of the proper
ignition switch diagnosis and testing procedures. Replace
the faulty ignition switch, as required.
4. Refer to Starter Motor in the index of this service
manual for the location of the proper starter motor
diagnosis and testing procedures. Replace the faulty
starter motor, as required.
TESTING
Before testing the starting system perform a visual
inspection of the starting system components and
connections. Refer to
Starting System
in the index
of this service manual for the location of the proper
starting system cleaning and inspection procedures.
tem wiring diagrams. Before performing this test, be
certain
that
the
following
procedures
are
accom-
plished:
²
The battery is fully-charged and load tested.
Refer to
Battery Charging
in the index of this ser-
vice manual for the location of the proper battery
charging procedures. Refer to
Battery
in the index of
this service manual for the location of the battery
diagnosis
COLD CRANKING TEST
Refer to
Starting System
in the index of this ser-
vice manual for the location of complete starting sys-
and
testing
procedures,
including
the
proper battery load test procedures.
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