JEEP CHEROKEE 1994 Service Repair Manual

8A - 18 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICSJ

USING ON-BOARD DIAGNOSTIC SYSTEM
OPERATION OF ON-BOARD DIAGNOSTIC
(OBD) SYSTEM
The Powertrain Control Module (PCM) monitors
critical input and output circuits of the charging sys-
tem making sure they are OK. Some are checked
continuously and some are checked only under cer-
tain conditions.
If OBD system senses that one critical circuit is
bad during the monitoring cycle, it will put a diag-
nostic trouble code into memory. Each input and out-
put circuit monitored by the OBD system has its own
diagnostic trouble code. The diagnostic trouble code
(DTC) will stay in memory as long as the circuit con-
tinues to be bad. If the problem does not happen
again after the fault code is put into memory, the
PCM is programmed to clear the memory after 50 en-
gine starts.
DIAGNOSTIC TROUBLE CODES (DTC)
Diagnostic trouble codes are two-digit numbers
flashed on Malfunction Indicator (Check Engine)
Lamp that identify which circuit is bad. In most
cases they do not identify which component in a cir-
cuit is bad. A trouble code description can be read us-
ing the DRB scan tool. Refer to Group 14 - Fuel
Systems for more information. Therefore, a DTC is
only a symptom, not necessarily the cause for the
problem. In some cases, because of the design of the
driveability test procedure, a DTC can be the reason
for the problem. It is important that the test proce-
dure be followed to understand what caused the DTC
of the on-board diagnostic system to be set.
HOW TO USE MALFUNCTION INDICATOR (CHECK
ENGINE) LAMP FOR DIAGNOSTIC TROUBLE
CODES
To start this function, cycle the ignition switch ON-
OFF-ON-OFF-ON within 5 seconds and any trouble
code stored in the PCM will be displayed. The Mal-
function Indicator (Check Engine) Lamp will display
a DTC by flashing on and off. There is a short pause
between flashes and a longer pause between digits.
All codes displayed are two digit numbers with a 4
second pause between codes.
An example of a code 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 and then flashes 7 times.
The 2 codes are 41 and 47. Any number of codes
can be displayed as long as they are in memory. The
lamp will flash until all are displayed (55 = End of
test).
CHARGING SYSTEM DIAGNOSTIC TROUBLE
CODES
See Generator Diagnostic Trouble Code chart for
diagnostic trouble codes which apply to the charging
system. Refer to the Powertrain Diagnostic Proce-
dures manal to diagnose an On-Board Diagnostic
System, Trouble Code.
GENERATOR DIAGNOSTIC TROUBLE CODE (DTC)
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 19

BATTERY/STARTER/GENERATOR SERVICE
CONTENTS
page page
BATTERY SERVICE PROCEDURES.......... 1
ENGINE STARTER MOTOR SERVICE
PROCEDURES......................... 4GENERATOR SERVICE PROCEDURES........ 7
SPECIFICATIONS....................... 10
BATTERY SERVICE PROCEDURES
GENERAL INFORMATION
This section covers battery removal and installa-
tion procedures only. For diagnostic procedures, refer
to Group 8A - Battery/Starting/Charging Systems Di-
agnostics.
BATTERY MAINTENANCE
(1) Inspect cable terminals for corrosion and dam-
age. Remove the corrosion using a wire brush, or
post and terminal cleaner, and a sodium bicarbonate/
water solution. Replace cables that have damaged or
deformed terminals.
Be sure filler caps or vents are installed when
washing battery to prevent solution from enter-
ing battery.
(2) Clean outside of battery case if the original
battery is to be installed. Clean top cover with di-
luted ammonia or a sodium bicarbonate/water solu-
tion to remove acid film. Flush with clean water.
Ensure that cleaning solution does not enter cells.
(3) Remove corrosion from the terminals with a
wire brush or post and terminal cleaner. Inspect the
case for cracks or other damage that would result in
leakage of electrolyte.
(4) Check electrolyte level in the battery. Use a
putty knife or other suitable wide tool to pry filler
caps off low maintenance battery (Fig. 1). Do not use
a screwdriver. Add distilled water to each cell until
the liquid reaches the bottom of the vent well. DO
NOT OVERFILL.
(5) Operate the engine immediately after adding
water (particularly in cold weather) to assure proper
mixing of the water and acid.
BATTERY REPLACEMENTÐLEFT HAND DRIVE
REMOVAL
(1) Make sure ignition switch is in OFF position
and all electrical accessories are OFF.
(2) Loosen the cable terminal clamps.
(3) If necessary, use a puller to remove cable ter-
minal clamps. Remove negative cable terminal clamp
first.WARNING: WEAR A SUITABLE PAIR OF RUBBER
GLOVES (NOT THE HOUSEHOLD TYPE) WHEN RE-
MOVING A BATTERY BY HAND. SAFETY GLASSES
ALSO SHOULD BE WORN. IF THE BATTERY IS
CRACKED OR LEAKING, THE ELECTROLYTE CAN
BURN THE SKIN AND EYES.
(4) Remove battery holddown, and remove battery
from vehicle (Figs. 2 and 3).
(5) Inspect battery tray and holddowns for corro-
sion. Remove corrosion using a wire brush and a so-
dium bicarbonate/water solution. Paint any exposed
bare metal. Replace damaged components (Figs. 4
and 5).
INSTALLATION
(1) Refer to Specifications to determine if battery
has correct classification and rating for the vehicle.
(2) Use a hydrometer to test the battery electro-
lyte. Charge battery if necessary.
(3) Position battery in tray. Ensure that positive
and negative terminals (posts) are correctly located.
The cables must reach their terminals (posts) with-
out stretching (Figs. 2 and 3).
Fig. 1 Removing Filler Cap
JBATTERY/STARTER/GENERATOR SERVICE 8B - 1

(4) Ensure that tang at battery base is positioned
in tray properly before tightening holddown.
CAUTION: It is imperative that the cables are con-
nected to the battery positive-to-positive and nega-
tive-to-negative. Reverse polarity will damage the
generator diodes and radio(s).
(5) Place felt washer on positive battery terminal.
(6) Connect positive cable first. Then connect neg-
ative cable. Tighten both cable terminal bolts to 8.5
Nzm (75 in. lbs.).(7) Apply a thin coating of petroleum jelly or chas-
sis grease to cable terminals and battery posts.
(8) Inspect negative cable connections on engine
and vehicle body for condition, security and electrical
continuity.
BATTERY REPLACEMENTÐRIGHT HAND DRIVE
REMOVAL
(1) Make sure ignition switch is in OFF position
and all electrical accessories are OFF.
Fig. 2 Battery HolddownÐXJ
Fig. 3 Battery HolddownÐYJ
Fig. 4 Battery TrayÐXJ
Fig. 5 Battery TrayÐYJ
8B - 2 BATTERY/STARTER/GENERATOR SERVICEJ

(2) Remove bolt and negative cable from battery
(Fig. 6).
(3) Remove bolt and positive cable from battery.
WARNING: WEAR A SUITABLE PAIR OF RUBBER
GLOVES (NOT THE HOUSEHOLD TYPE) WHEN RE-
MOVING A BATTERY BY HAND. SAFETY GLASSES
ALSO SHOULD BE WORN. IF THE BATTERY ISCRACKED OR LEAKING, THE ELECTROLYTE CAN
BURN THE SKIN AND EYES.
(4) Remove battery holddown and battery from ve-
hicle.
(5) Inspect battery tray and holddowns for corro-
sion. Remove corrosion using a wire brush and a so-
dium bicarbonate/water solution. Paint any exposed
bare metal. Replace damaged components.
INSTALLATION
(1) Refer to Specifications to determine if battery
has correct classification and rating for the vehicle.
(2) Use a hydrometer to test the battery electro-
lyte. Charge battery if necessary.
(3) Position battery in tray. Ensure that positive
and negative terminals are correctly located. The ca-
bles must reach their terminals without stretching
(Fig. 6).
(4) Ensure that battery base is positioned in tray
properly before tightening holddown.
CAUTION: It is imperative that the cables are con-
nected to the battery positive-to-positive and nega-
tive-to-negative. Reverse polarity will damage the
generator diodes and radio(s).
(5) Connect positive cable first. Then connect neg-
ative cable. Tighten both cable terminal bolts to
10-20 Nzm (90-178 in. lbs.).
(6) Inspect negative cable connections on engine
and vehicle body for condition, security and electrical
continuity.
Fig. 6 Battery Cable Attachment
JBATTERY/STARTER/GENERATOR SERVICE 8B - 3

ENGINE STARTER MOTOR SERVICE PROCEDURES
INDEX
page page
2.5L Starter General Information.............. 4
2.5L Starter Motor Removal/Installation......... 5
4.0L Starter General Information.............. 6
4.0L Starter Motor Removal/Installation......... 6General Information........................ 4
Park/Neutral Position Switch................. 6
Starter Relay Replacement.................. 4
GENERAL INFORMATION
This section will cover the starting system compo-
nent service procedures only. For diagnostic proce-
dures, refer to Group 8A - Battery/Starting/Charging
Systems Diagnostics.
Starting system components: battery, starter mo-
tor, starter relay, starter solenoid, ignition switch,
connecting wires and battery cables. A park/neutral
position switch is used with automatic transmissions.
STARTER RELAY REPLACEMENT
The starter relay is located in the Power Distribu-
tion Center (Figs. 1 and 2). Refer to underside of
Power Distribution Center cover for relay location.
(1) Disconnect negative cable from battery.
(2) Replace relay.
(3) Connect negative cable to battery.
(4) Test relay operation.
2.5L STARTER GENERAL INFORMATION
The 2.5L engine starter motor incorporates several
features to create an efficient, lightweight unit.
A planetary gear system (intermediate transmis-
sion) between the electric motor and pinion shaftmakes it possible to reduce the dimensions of the
starter. This also makes it possible to obtain a higher
rotational speed to produce the same torque at the
pinion.
The permanent magnet field consists of six two-
component high strength magnets. The magnets are
aligned according to their polarity and are perma-
nently fixed in the starter frame.
The brush holder plate consists of a plastic base-
plate with four tubular brush holders.
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 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 magnets may
be damaged and rendered unserviceable.
²Ensure cleanliness when performing repairs.
Fig. 1 Power Distribution CenterÐXJ
Fig. 2 Power Distribution CenterÐYJ
8B - 4 BATTERY/STARTER/GENERATOR SERVICEJ

²Metal chips are attracted by the magnets and may
not be completely removed from the starter frame.
Chips in the ring gear can lead to failure of the
starter.
2.5L STARTER MOTOR REMOVAL/INSTALLATION
XJÐ2.5L ENGINE
(1) Disconnect negative cable from battery.
(2) Remove exhaust clamp from bracket (Fig. 3).
(3) Remove nut and bolt from forward end of brace
rod (automatic transmission only).
(4) Remove nut from lower end of brace rod (auto-
matic transmission only).
(5) Remove brace rod and bracket (automatic
transmission only).
(6) Remove nut, bolt and bracket from bell housing
(manual transmission only).
(7) Disconnect battery cable and solenoid feed wire
from solenoid (Fig. 4).
(8) Remove starter motor mounting bolts, starter
motor and shims.
Two shim thicknesses are available. One is
0.381 mm (0.015 in.) and the other is 1.143 mm
(0.045 in.). Refer to Group 8A for proper shim se-
lection.
(9) To install starter motor, reverse the removal
procedures and torque mounting hardware as shown.
(10) Connect negative cable to battery.
YJÐ2.5L ENGINE
(1) Disconnect negative cable from battery.
(2) Disconnect battery cable from starter motor
B+ terminal (Fig. 5).(3) Disconnect solenoid feed wire.
(4) Remove starter motor mounting bolts.
(5) Remove starter motor and shims.
Two shim thicknesses are available. One is
0.381 mm (0.015 in.) and the other is 1.143 mm
(0.045 in.). Refer to Group 8A for proper shim se-
lection.
(6) To install starter motor, reverse removal proce-
dures and torque mounting hardware as shown.
(7) Connect negative cable to battery.
Fig. 3 Exhaust Clamp and Brace RemovalÐ2.5L XJ
Fig. 4 Starter Motor Removal/InstallationÐ2.5L XJ
Fig. 5 Starter Motor Removal/InstallationÐ2.5L YJ
JBATTERY/STARTER/GENERATOR SERVICE 8B - 5

4.0L STARTER GENERAL INFORMATION
The Mitsubishi starter motor is a light-weight unit
featuring a planetary gear drive and permanent
magnets for current induction.
The planetary gear drive is splined to both the ar-
mature shaft and overrunning clutch. Starter torque
is transmitted to the overrunning clutch pinion
through the planetary gears which provide higher ro-
tational speeds.
The starter magnetic field is produced by six per-
manent magnets. The magnets are mounted in the
starter frame and positioned according to polarity.
They are permanently attached to the frame and are
not removable.
The starter motor is activated by a solenoid
mounted on the overrunning clutch housing.
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 frame. Doing so
may damage the magnets. It may be clamped by the
mounting flange ONLY.
CAUTION: Do not connect the starter motor incor-
rectly when performing tests. The magnets may be
damaged and rendered unserviceable.
²Ensure cleanliness when performing repairs.
²Metal chips are attracted by the magnets and may
not be completely removed from the starter frame.
Chips in the ring gear can lead to failure of the
starter.
4.0L STARTER MOTOR REMOVAL/INSTALLATION
(1) Disconnect negative cable from battery.
(2) Raise and support vehicle.(3) Disconnect battery wire and solenoid feed wire.
(4) Remove starter lower mounting bolt (Fig. 6).
(5) Remove starter upper mounting bolt and re-
move starter.
(6) To install starter motor, reverse the removal
procedures and torque mounting hardware as shown.
(7) Remove vehicle support and lower vehicle.
(8) Install negative cable to battery.
PARK/NEUTRAL POSITION SWITCH
Refer to Group 21 for diagnostic, removal and in-
stallation procedures.
Check linkage adjustment before replacing the
switch.
Fig. 6 Starter Motor Removal/Installation (Typical)
8B - 6 BATTERY/STARTER/GENERATOR SERVICEJ

GENERATOR SERVICE PROCEDURES
GENERAL
The generator is belt-driven by the engine. All en-
gines use serpentine drive. This section will cover
generator removal and installation. The generator is
not serviceable. Information covering on-vehicle test-
ing can be found in Group 8A - Battery/Starting/
Charging Systems Diagnostics.
GENERATOR REPLACEMENTÐLEFT HAND DRIVE
WARNING: FAILURE TO DISCONNECT NEGATIVE
CABLE FROM BATTERY BEFORE DISCONNECTING
RED (OUTPUT) WIRE CONNECTOR FROM GENER-
ATOR CAN RESULT IN INJURY.
ALL YJ AND XJ WITH 2.5L ENGINE
Belt tension is adjusted at the power steering pump
(or idler pulley if not equipped with power steering).
To replace generator:
(1) Disconnect negative cable from battery.
(2) Loosen rear mounting bolts (Fig. 1 or 2).
(3) Loosen power steering pump/idler pulley pivot
bolt and lock nut (Fig. 3 or 4).
(4) Loosen adjusting bolt to remove belt.
(5) Remove generator B+ terminal nut, 2 field ter-
minal nuts, ground and harness holddown nuts (Fig.
5). Remove wire connector assembly.
(6) Remove 2 generator mounting bolts and re-
move generator from vehicle.
(7) Install generator with 2 mounting bolts. Torque
bolts to 55 Nzm (41 ft. lbs.).
(8) Attach generator wires.
CAUTION: Never force a belt over a pulley rim us-
ing a screwdriver as the synthetic fiber may be
damaged.CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. The
engine may overheat because the water pump will
be rotating in the wrong direction if the belt is in-
stalled incorrectly. Refer to the belt routing label in
engine compartment, or see Group 7 - Belt Sche-
matics.
(9) Place serpentine belt over pulley.
(10) Belt tension adjustment is made at power
steering pump or idler pulley (Figs. 1 or 2).
(11) Turn adjusting bolt until belt has correct ten-
sion. See Belt Tension in Specifications.
Fig. 1 Powering Steering Pump Rear Mounting
BoltsÐExcept XJ With 4.0L
Fig. 2 Idler Pulley Rear Mounting BoltsÐExcept XJ
With 4.0L
Fig. 3 Power Steering Pump Front Mounting
BoltsÐExcept XJ With 4.0L
JBATTERY/STARTER/GENERATOR SERVICE 8B - 7