tire size JEEP CHEROKEE 1995 Service Repair Manual

even tire wear. The wheel toe position is thefinal
front wheel alignment adjustment.
²STEERING AXIS INCLINATION ANGLE is mea-
sured in degrees and is the angle that the steering
knuckles are tilted (Fig. 1). The inclination angle has
a fixed relationship with the camber angle. It will not
change except when a spindle or ball stud is dam-
aged or bent. The angle is not adjustable, the dam-
aged component(s) must be replaced to correct mis-
alignment.
WARNING: DO NOT ATTEMPT TO MODIFY ANY
SUSPENSION OR STEERING COMPONENT BY
HEATING AND BENDING.
PRE-ALIGNMENT INSPECTION
Before starting a front wheel alignment, the follow-
ing inspection and necessary corrections must be
completed.(1) Tires with the same recommended air pressure,
size, and thread wear. Refer to Group 22, Tires And
Wheels for diagnosis information.
(2) Front wheel bearings for wear and looseness.
(3) Ball studs, steering linkage pivot points and
steering gear for looseness, roughness, binding or
wear. Refer to Group 19, Steering for additional in-
formation.
(4) Front wheels for excessive radial or lateral
runout and unbalance. Refer to Group 22, Tires And
Wheels for diagnosis information.
(5) Suspension components for wear. Check compo-
nents for correct torque. Refer to Groups 2 and 3,
Suspension and Axle for additional information.
2 - 6 FRONT SUSPENSION AND AXLEJ

ABS BRAKE DIAGNOSIS
INDEX
page page
ABS Diagnostic Connector................... 3
ABS Warning Light Display................... 3
Antilock ECU and Hcu Diagnosis............... 3
DRB Scan Tool............................ 3General Information........................ 3
Normal Operating Conditions.................. 3
Wheel/Tire Size and Input Signals.............. 3
GENERAL INFORMATION
The DRB scan tool is required for ABS diagnosis.
The scan tool is used to identify ABS circuit faults.
Once a faulty circuit has been identified, refer to
the appropriate chassis/body diagnostic manual for
individual component testing.
ABS WARNING LIGHT DISPLAY
The amber antilock light illuminates at startup as
part of the system self check feature. The light illu-
minates for 2-3 seconds then goes off as part of the
normal check routine.
An ABS circuit fault is indicated when the amber
light remains on after startup, or illuminates during
vehicle operation.
Verify that a fault is actually related to the ABS
system before making repairs. For example, if the
red warning illuminates but the ABS light does not,
the problem is related to a service brake component
and not the ABS system. Or, if neither light illumi-
nates but a brake problem is noted, again, the prob-
lem is with a service brake component and not with
the ABS system.
ABS DIAGNOSTIC CONNECTOR
The ABS diagnostic connector is inside the vehicle.
The connector is the access point for the DRB scan tool.
On XJ models, the connector is located under the
instrument panel to the right of the steering column.
On some models, the connecter may be tucked under
the carpeting on the transmission tunnel. The con-
necter is a black, 6-way type.
On YJ models, the connector is under the instru-
ment panel by the the driver side kick panel. The
connecter is a black, 6 or 8-way type.
The DRB scan tool kit contains adapter cords for
both types of connecter. Use the appropriate cord for
test hookup.
DRB SCAN TOOL
ABS diagnosis is performed with the DRB scan tool.
Refer to the DRB scan tool manual for test hookup and
procedures. Diagnosis information is provided in the ap-
propriate chassis/body diagnostic manual.
WHEEL/TIRE SIZE AND INPUT SIGNALS
Antilock system operation is dependant on accurate
signals from the wheel speed sensors. Ideally, the ve-
hicle wheels and tires should all be the same size
and type. However, the Jeep ABS system is designed
to operate with a compact spare tire installed.
NORMAL OPERATING CONDITIONS
Sound Levels
The hydraulic control unit pump and solenoid valves
may produce some sound as they cycle on and off. This
is a normal condition and should not be mistaken for
faulty operation. Under most conditions, pump and so-
lenoid valve operating sounds will not be audible.
Vehicle Response In Antilock Mode
During antilock braking, the hydraulic control unit
solenoid valves cycle rapidly in response to antilock
electronic control unit signals.
The driver will experience a pulsing sensation
within the vehicle as the solenoids decrease, hold, or
increase pressure as needed. Brake pedal pulsing will
also be noted and is anormal condition.
Steering Response
A modest amount of steering input is required dur-
ing extremely high deceleration braking, or when
braking on differing traction surfaces. An example of
differing traction surfaces would be when the left
side wheels are on ice and the right side wheels are
on dry pavement.
Owner Induced Faults
Driving away with the parking brakes still applied
will cause warning light illumination. Pumping the
brake pedal will also generate a system fault and in-
terfere with ABS system operation.
ANTILOCK ECU AND HCU DIAGNOSIS
An ECU or HCU fault can only be determined
through testing with the DRB scan tool. Do not re-
place either component unless a fault is actually in-
dicated.
JABS BRAKE DIAGNOSIS 5 - 3

produce a condition similar to grab as the tire loses
and recovers traction.
Flat-spotted tires can cause vibration and wheel
tramp and generate shudder during brake operation.
A tire with internal damage such as a severe bruise
or ply separation can cause vibration and pull. The
pull will be magnified when braking.
DIAGNOSING PARKING BRAKE MALFUNCTIONS
Adjustment Mechanism
Parking brake adjustment is controlled by a ca-
ble tensioner mechanism. The cable tensioner,
once adjusted at the factory, will not need further
attention under normal circumstances. There are
only two instances when adjustment is required.
The first is when a new tensioner, or cables have
been installed. And the second, is when the ten-
sioner and cables are disconnected for access to
other brake components.
Parking Brake Switch And Warning Light Illumination
The parking brake switch on the lever, or foot
pedal, is in circuit with the red warning light. The
switch will illuminate the red light only when the
parking brakes are applied. If the light remains on
after parking brake release, the switch or wires are
faulty, or cable tensioner adjustment is incorrect.
If the red light comes on while the vehicle is in mo-
tion and brake pedal height decreases, a fault has oc-
curred in the front or rear brake hydraulic system.
Parking Brake problem Causes
In most cases, the actual cause of an improperly
functioning parking brake (too loose/too tight/wont
hold), can be traced to a drum brake component.
The leading cause of improper parking brake
operation, is excessive clearance between the
brakeshoes and the drum surface. Excessive
clearance is a result of: lining and/or drum
wear; oversize drums; or inoperative shoe ad-
juster components.
Excessive parking brake lever travel (sometimes de-
scribed as a loose lever or too loose condition), is the re-
sult of worn brakeshoes/drums, improper brakeshoe
adjustment, or incorrectly assembled brake parts.
A ``too loose'' condition can also be caused by inop-
erative brakeshoe adjusters. If the adjusters are mis-
assembled, they will not function. In addition, since
the adjuster mechanism only works during reverse
stops, it is important that complete stops be made.
The adjuster mechanism does not operate when roll-
ing stops are made in reverse. The vehicle must be
brought to a complete halt before the adjuster lever
will turn the adjuster screw.
A condition where the parking brakes do not hold, will
most probably be due to a wheel brake component.
Items to look for when diagnosing a parking brake
problem, are:
²rear brakeshoe wear or adjuster problem
²rear brake drum wear
²brake drums machined beyond allowable diameter
(oversize)
²parking brake front cable not secured to lever
²parking brake rear cable seized
²parking brake strut reversed
²parking brake strut not seated in both shoes
²parking brake lever not seated in secondary shoe
²parking brake lever or brakeshoe bind on support
plate
²brakeshoes reversed
²adjuster screws seized
²adjuster screws reversed
²holddown or return springs misassembled or lack
tension
²wheel cylinder pistons seized
Brake drums that are machined oversize are diffi-
cult to identify without inspection. If oversize drums
are suspected, diameter of the braking surface will
have to be checked with an accurate drum gauge.
Oversize drums will cause low brake pedal and lack
of parking brake holding ability.
Improper parking brake strut and lever installation
will result in unsatisfactory parking brake operation.
Intermixing the adjuster screws will cause drag, bind
and pull along with poor parking brake operation.
Parking brake adjustment and parts replacement pro-
cedures are described in the Parking Brake section.
MASTER CYLINDER/POWER BOOSTER TEST
(1) Start engine and check booster vacuum hose
connections. Hissing noise indicates vacuum leak.
Correct any vacuum leak before proceeding.
(2) Stop engine and shift transmission into Neu-
tral.
(3) Pump brake pedal until all vacuum reserve in
booster is depleted.
(4) Press and hold brake pedal under light foot
pressure.
(a) If pedal holds firm, proceed to step (5).
(b) If pedal does not hold firm and falls away,
master cylinder is faulty due to internal leakage.
Overhaul or replace cylinder.
(5) Start engine and note pedal action.
(a) If pedal falls away slightly under light foot
pressure then holds firm, proceed to step (6).
(b) If no pedal action is discernible, or hard pedal
is noted, power booster or vacuum check valve is
faulty. Install known good check valve and repeat
steps (2) through (5).
(6) Rebuild booster vacuum reserve as follows: Re-
lease brake pedal. Increase engine speed to 1500
rpm, close throttle and immediately turn off ignition.
5 - 8 SERVICE BRAKE DIAGNOSISJ

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

The high-line cluster includes the following gauges:
²coolant temperature gauge
²fuel gauge
²oil pressure gauge
²speedometer/odometer
²tachometer
²trip odometer
²voltmeter.
The high-line cluster includes provisions for the fol-
lowing indicator lamps:
²anti-lock brake system lamp
²brake warning lamp
²four-wheel drive indicator lamps
²headlamp high beam indicator lamp
²low fuel warning lamp
²low washer fluid warning lamp
²malfunction indicator (Check Engine) lamp
²seat belt reminder lamp
²turn signal indicator lamps
²upshift indicator lamp.
GAUGES
With the ignition switch in the ON or START posi-
tion, voltage is supplied to all gauges through the in-
strument cluster gauge area printed circuit. With the
ignition switch in the OFF position, voltage is not
supplied to the gauges. A gauge pointer may remain
within the gauge scale after the ignition switch is
OFF. However, the gauges do not accurately indicate
any vehicle condition unless the ignition switch is
ON.
All gauges except the odometer are air core mag-
netic units. Two fixed electromagnetic coils are lo-
cated within the gauge. These coils are wrapped at
right angles to each other around a movable perma-
nent magnet. The movable magnet is suspended
within the coils on one end of a shaft. The gauge nee-
dle is attached to the other end of the shaft.
One of the coils has a fixed current flowing through
it to maintain a constant magnetic field strength.
Current flow through the second coil changes, which
causes changes in its magnetic field strength. The
current flowing through the second coil can be
changed by:
²a variable resistor-type sending unit (fuel level,
coolant temperature, or oil pressure)
²changes in electrical system voltage (voltmeter)
²electronic control circuitry (speedometer/odometer,
tachometer).
The gauge needle moves as the movable permanent
magnet aligns itself to the changing magnetic fields
created around it by the electromagnets.
COOLANT TEMPERATURE GAUGE
The coolant temperature gauge gives an indication
of engine coolant temperature. The coolant tempera-
ture sending unit is a thermistor that changes elec-
trical resistance with changes in engine coolanttemperature. High sending unit resistance causes
low coolant temperature readings. Low resistance
causes high coolant temperature readings.
The gauge will read at the high end of the scale
when the ignition switch is turned to the START po-
sition. This is caused by the bulb test circuit wiring
provision. The same wiring is used for the high-line
cluster with a coolant temperature gauge and the
low-line cluster with a coolant temperature warning
lamp. Sending unit resistance values are shown in a
chart in Specifications.
FUEL GAUGE
The fuel gauge gives an indication of the level of
fuel in the fuel tank. The fuel gauge sending unit has
a float attached to a swing-arm in the fuel tank. The
float moves up or down within the fuel tank as fuel
level changes. As the float moves, an electrical con-
tact on the swing-arm wipes across a resistor coil,
which changes sending unit resistance. High sending
unit resistance causes low fuel level readings. Low
resistance causes high fuel level readings. Sending
unit resistance values are shown in a chart in Spec-
ifications.
OIL PRESSURE GAUGE
The oil pressure gauge gives an indication of en-
gine oil pressure. The combination oil pressure send-
ing unit contains a flexible diaphragm. The
diaphragm moves in response to changes in engine
oil pressure. As the diaphragm moves, sending unit
resistance increases or decreases. High resistance on
the gauge side of the sending unit causes high oil
pressure readings. Low resistance causes low oil
pressure readings. Sending unit resistance values are
shown in a chart in Specifications.
SPEEDOMETER/ODOMETER
The speedometer/odometer gives an indication of
vehicle speed and travel distance. The speedometer
receives a vehicle speed pulse signal from the Vehicle
Speed Sensor (VSS). An electronic integrated circuit
contained within the speedometer reads and analyzes
the pulse signal. It then adjusts the ground path re-
sistance of one electromagnet in the gauge to control
needle movement. It also sends signals to an electric
stepper motor to control movement of the odometer
number rolls. Frequency values for the pulse signal
are shown in a chart in Specifications.
The VSS is mounted to an adapter near the trans-
mission (two-wheel drive) or transfer case (four-wheel
drive) output shaft. The sensor is driven through the
adapter by a speedometer pinion gear. The adapter
and pinion vary with transmission, transfer case,
axle ratio and tire size. Refer to Group 21 - Trans-
mission and Transfer Case for more information.
8E - 2 INSTRUMENT PANEL AND GAUGESÐXJJ

(5) Probe cavity B1 of cluster connector A. Check
for continuity to a good ground. There should be no
continuity. If OK, go to next step. If not OK, repair
short circuit as required.
(6) Still probing cavity B1 of cluster connector A,
check for continuity to cavity B of sending unit body
half connector. There should be continuity. If OK, re-
place gauge. If not OK, repair open circuit as re-
quired.
OIL PRESSURE GAUGE
The diagnosis found here addresses an inoperative
gauge condition. If the problem being diagnosed is re-
lated to gauge accuracy, be certain to confirm that
problem is with gauge and not with engine oiling sys-
tem performance. Actual engine oil pressure should
be checked with a test gauge and compared to gauge
readings before you proceed with gauge diagnosis.
Refer to Group 9 - Engines for more information.
(1) Turn ignition switch to ON. Disconnect oil pres-
sure sending unit connector. The sending unit (Fig. 3)
is located on right side of engine block. On 2.5L en-
gine, it is just forward of ignition distributor and just
to the rear of generator mounting bracket. On 4.0L
engine, it is just to the rear of ignition distributor
and above oil filter adapter. The gauge needle should
move to high end of gauge scale. If OK, go to next
step. If not OK, go to step 3.
(2) Install a jumper wire from sending unit wiring
to ground. The gauge needle should move to low end
of gauge scale. If OK, replace sending unit. If not
OK, remove jumper wire and go to next step.
(3) Turn ignition switch to OFF. Disconnect battery
negative cable. Remove instrument cluster bezel and
cluster assembly. Disconnect instrument cluster con-
nector A.
(4) Probe cavity B7 (cavity B8 - RHD) of cluster
connector A. Check for continuity to a good ground.
There should be no continuity. If OK, go to next step.
If not OK, repair short circuit as required.(5) Still probing cavity B7 (cavity B8 - RHD) of
cluster connector A, check for continuity to sending
unit wire connector. There should be continuity. If
OK, replace gauge. If not OK, repair open circuit as
required.
SPEEDOMETER/ODOMETER
The diagnosis found here addresses an inoperative
gauge condition. If the problem being diagnosed is re-
lated to gauge accuracy, be certain to confirm that
problem is with gauge and not with incorrect speed-
ometer pinion, axle ratio or tire size. Refer to Group
21 - Transmission and Transfer Case for more infor-
mation.
(1) Perform vehicle speed sensor test as described
in the appropriate Powertrain Diagnostic Procedures
manual. If OK, go to next step. If not OK, replace ve-
hicle speed sensor.
(2) Disconnect battery negative cable. Unplug vehi-
cle speed sensor, PCM, and daytime running lamp
module connectors. Remove instrument cluster bezel
and cluster assembly. Disconnect instrument cluster
connector A.
(3) Probe cavity A5 (cavity B6 - RHD) of cluster
connector A. Check for continuity to a good ground.
There should be no continuity. If OK, go to next step.
If not OK, repair short circuit as required.
(4) Still probing cavity A5 (cavity B6 - RHD) of
cluster connector A, check for continuity to cavity 1 of
vehicle speed sensor connector (Fig. 4). There should
be continuity. If OK, replace speedometer/odometer. If
not OK, repair open circuit as required.
TACHOMETER
(1) With engine running, check for tachometer sig-
nal at pin 43 of PCM connector (Fig. 5). See Tachom-
eter Calibration chart in Specifications. If OK, go to
next step. If not OK, replace PCM.
Fig. 2 Fuel Gauge Sending Unit ConnectorFig. 3 Oil Pressure Switch/Sending Unit - Typical
8E - 6 INSTRUMENT PANEL AND GAUGESÐXJJ

The gauge needle moves as the movable permanent
magnet aligns itself to the changing magnetic fields
created around it by the electromagnets.
COOLANT TEMPERATURE GAUGE
The coolant temperature gauge gives an indication
of engine coolant temperature. The coolant tempera-
ture sending unit is a thermistor that changes elec-
trical resistance with changes in engine coolant
temperature. High sending unit resistance causes
low coolant temperature readings. Low resistance
causes high coolant temperature readings. Sending
unit resistance values are shown in a chart in Spec-
ifications.
FUEL GAUGE
The fuel gauge gives an indication of the level of
fuel in the fuel tank. The fuel gauge sending unit has
a float attached to a swing-arm in the fuel tank. The
float moves up or down within the fuel tank as fuel
level changes. As the float moves, an electrical con-
tact on the swing-arm wipes across a resistor coil,
which changes sending unit resistance. High sending
unit resistance causes high fuel level readings. Low
resistance causes low fuel level readings. Sending
unit resistance values are shown in a chart in Spec-
ifications.
OIL PRESSURE GAUGE
The oil pressure gauge gives an indication of en-
gine oil pressure. The combination oil pressure send-
ing unit contains a flexible diaphragm. The
diaphragm moves in response to changes in engine
oil pressure. As the diaphragm moves, sending unit
resistance increases or decreases. High resistance on
the gauge side of the sending unit causes high oil
pressure readings. Low resistance causes low oil
pressure readings. Sending unit resistance values are
shown in a chart in Specifications.
SPEEDOMETER/ODOMETER
The speedometer/odometer give an indication of ve-
hicle speed and travel distance. The speedometer re-
ceives a vehicle speed pulse signal from the Vehicle
Speed Sensor (VSS). An electronic integrated circuit
contained within the speedometer reads and analyzes
the pulse signal. It then adjusts the ground path re-
sistance of one electromagnet in the gauge to control
needle movement. It also sends signals to an electric
stepper motor to control movement of the odometer
number rolls. Frequency values for the pulse signal
are shown in a chart in Specifications.
The VSS is mounted to an adapter near the trans-
fer case output shaft. The sensor is driven through
the adapter by a speedometer pinion gear. The
adapter and pinion vary with transmission, axle ratio
and tire size. Refer to Group 21 - Transmission and
Transfer Case for more information.
TACHOMETER
The tachometer gives an indication of engine speed
in Revolutions-Per-Minute (RPM). With the engine
running, the tachometer receives an engine speed
pulse signal from the Powertrain Control Module
(PCM). An electronic integrated circuit contained
within the tachometer reads and analyzes the pulse
signal. It then adjusts the ground path resistance of
one electromagnet in the gauge to control needle
movement. Frequency values for the pulse signal are
shown in a chart in Specifications.
TRIP ODOMETER
The trip odometer is driven by the same electronic
integrated circuit as the speedometer/odometer. How-
ever, by depressing the trip odometer reset knob on
the face of the speedometer, the trip odometer can be
reset to zero. The trip odometer is serviced only as a
part of the speedometer/odometer gauge assembly.
VOLTMETER
The voltmeter is connected in parallel with the bat-
tery. With the ignition switch ON, the voltmeter in-
dicates battery or generator output voltage,
whichever is greater.
INDICATOR LAMPS
All indicator lamps, except the four-wheel drive in-
dicator, are located in the main cluster tell-tale area
above the steering column opening. Each of the
lamps is served by the main cluster printed circuit
and cluster connector. The four-wheel drive indicator
lamp is located in the gauge package cluster and is
served by the gauge package printed circuit and clus-
ter connector.
Up to eleven indicator lamps can be found in the
tell-tale area of the main cluster. These lamps are ar-
ranged in two rows, with six lamps in the upper row
and five lamps in the lower row.
ANTI-LOCK BRAKE SYSTEM LAMP
The Anti-Lock Brake System (ABS) lamp is
switched to ground by the ABS module. The module
lights the lamp when the ignition switch is turned to
the START position as a bulb test. The lamp will
stay on for 3 to 5 seconds after vehicle start-up to in-
dicate a system self-test is in process. If the lamp re-
mains on after start-up, or comes on and stays on
while driving, it may indicate that the ABS module
has detected a system malfunction or that the system
has become inoperative. Refer to Group 5 - Brakes
for more information.
BRAKE WARNING LAMP
The brake warning lamp warns the driver that the
parking brake is applied or that the pressures in the
two halves of the split brake hydraulic system are
unequal. With the ignition switch turned ON, battery
JINSTRUMENT PANEL AND GAUGESÐYJ 8E - 25

continuity. If OK, go to next step. If not OK, repair
circuit to ground as required.
(4) Remove center instrument cluster bezel and
gauge package cluster assembly. Disconnect cluster
connector.
(5) Probe cavity 6 of cluster connector. Check for
continuity to a good ground. There should be no con-
tinuity. If OK, go to next step. If not OK, repair short
circuit as required.
(6) Still probing cavity 6 of cluster connector, check
for continuity to cavity 2 of sending unit wiring body
half connector. There should be continuity. If OK, re-
place gauge. If not OK, repair open circuit as re-
quired.
OIL PRESSURE GAUGE
The diagnosis found here addresses an inoperative
gauge condition. If the problem being diagnosed is re-
lated to gauge accuracy, be certain to confirm that
problem is with gauge and not with engine oiling sys-
tem performance. Actual engine oil pressure should
be checked with a test gauge and compared to gauge
readings before you proceed with gauge diagnosis.
Refer to Group 9 - Engines for more information.
(1) Turn ignition switch to ON. Disconnect oil pres-
sure sending unit connector. The sending unit (Fig. 3)
is located on right side of engine block. On 2.5L en-
gine, it is just forward of ignition distributor and just
to the rear of generator mounting bracket. On 4.0L
engine, it is just to the rear of ignition distributor
and above oil filter adapter. The gauge needle should
move to high end of gauge scale. If OK, go to next
step. If not OK, go to step 3.
(2) Install a jumper wire from sending unit wiring
to ground. The gauge needle should move to low end
of gauge scale. If OK, replace sending unit. If not
OK, remove jumper wire and go to next step.(3) Turn ignition switch to OFF. Disconnect battery
negative cable. Remove center instrument cluster be-
zel and gauge package cluster assembly. Disconnect
cluster connector.
(4) Probe cavity 9 of cluster connector. Check for
continuity to a good ground. There should be no con-
tinuity. If OK, go to next step. If not OK, repair short
circuit as required.
(5) Still probing cavity 9 of cluster connector, check
for continuity to sending unit wire connector. There
should be continuity. If OK, replace gauge. If not OK,
repair open circuit as required.
SPEEDOMETER/ODOMETER
The diagnosis found here addresses an inoperative
gauge condition. If the problem being diagnosed is re-
lated to gauge accuracy, be certain to confirm that
problem is with gauge and not with incorrect speed-
ometer pinion, axle ratio or tire size. Refer to Group
21 - Transmission and Transfer Case for more infor-
mation.
(1) Perform vehicle speed sensor test as described
in the appropriate Powertrain Diagnostic Procedures
manual. If OK, go to next step. If not OK, replace ve-
hicle speed sensor.
(2) Disconnect battery negative cable. Unplug vehi-
cle speed sensor, PCM, and daytime running lamp
module connectors. Remove left instrument cluster
bezel and main cluster assembly. Disconnect cluster
connector.
(3) Probe cavity 13 of cluster connector. Check for
continuity to a good ground. There should be no con-
tinuity. If OK, go to next step. If not OK, repair short
circuit as required.
(4) Still probing cavity 13 of cluster connector,
check for continuity to cavity 1 of vehicle speed sen-
sor connector (Fig. 4). There should be continuity. If
OK, replace speedometer/odometer. If not OK, repair
open circuit as required.
Fig. 2 Fuel Gauge Sending Unit ConnectorFig. 3 Oil Pressure Sending Unit - Typical
8E - 28 INSTRUMENT PANEL AND GAUGESÐYJJ

CONNECTING ROD BEARING CLEARANCE
Engine connecting rod bearing clearances can be
determined by use of Plastigage, or equivalent. The
following is the recommended procedures for the use
of Plastigage:
(1) Remove oil film from surface to be checked.
Plastigage is soluble in oil.
(2) Place a piece of Plastigage across the entire width
of the bearing cap shell (Fig. 2). Position the Plastigage
approximately 6.35 mm (1/4 inch) off center and away
from the oil holes. In addition, suspect areas can be
checked by placing the Plastigage in the suspect area.
(3) The crankshaft must be turned until the connect-
ing rod to be checked starts moving toward the top of
the engine. Only then should the rod cap with Plasti-
gage in place be assembled. Tighten the rod cap nut to
45 Nzm (33 ft. lbs.) torque.DO NOT rotate the crank-
shaft or the Plastigage may be smeared, giving in-
accurate results.
(4) Remove the bearing cap and compare the width
of the flattened Plastigage with the scale provided on
the package (Fig. 3). Plastigage generally comes in 2
scales (one scale is in inches and the other is a met-
ric scale). Locate the band closest to the same width.
This band shows the amount of clearance. Differ-
ences in readings between the ends indicate the
amount of taper present. Record all readings taken
(refer to Engine Specifications).
(5) Plastigage is available in a variety of clearance
ranges. The 0.025-0.076 mm (0.001-0.003 inch) range
is usually the most appropriate for checking engine
bearing clearances.
REPAIR DAMAGED OR WORN THREADS
Damaged or worn threads can be repaired. Essen-
tially, this repair consists of:
²Drilling out worn or damaged threads.
²Tapping the hole with a special Heli-Coil Tap, or
equivalent.
²Installing an insert into the tapped hole.
This brings the hole back to its original thread
size.
CAUTION: Be sure that the tapped holes maintain
the original center line.Heli-Coil tools and inserts are readily available
from automotive parts jobbers.
SERVICE ENGINE ASSEMBLY (SHORT BLOCK)
A service replacement engine assembly (short
block) may be installed whenever the original cylin-
der block is defective or damaged beyond repair. It
consists of the cylinder block, crankshaft, piston and
rod assemblies. If needed, the camshaft must be pro-
cured separately and installed before the engine is
installed in the vehicle.
A short block is identified with the letter ``S'' stamped
on the same machined surface where the build date
code is stamped for complete engine assemblies.
Installation includes the transfer of components
from the defective or damaged original engine. Fol-
low the appropriate procedures for cleaning, inspec-
tion and torque tightening.
HYDROSTATIC LOCK
When an engine is suspected of hydrostatic lock
(regardless of what caused the problem), follow the
steps below.
(1) Perform the Fuel Pressure Release Procedure
(refer to Group 14, Fuel System).
(2) Disconnect the negative cable from the battery.
(3) Inspect air cleaner, induction system and in-
take manifold to ensure system is dry and clear of
foreign material.
(4) Place a shop towel around the spark plugs to
catch any fluid that may possibly be under pressure in
the cylinder head. Remove the plugs from the engine.
CAUTION: DO NOT use the starter motor to rotate
the crankshaft. Severe damage could occur.
(5) With all spark plugs removed, rotate the crank-
shaft using a breaker bar and socket.
(6) Identify the fluid in the cylinders (i.e. coolant,
fuel, oil, etc.).
(7) Make sure all fluid has been removed from the
cylinders.
(8) Repair engine or components as necessary to
prevent this problem from occurring again.
(9) Squirt engine oil into the cylinders to lubricate
the walls. This will prevent damage on restart.
(10) Install new spark plugs. Tighten the spark
plugs to 37 Nzm (27 ft. lbs.) torque.
(11) Drain engine oil. Remove and discard the oil
filter.
(12) Install the drain plug. Tighten the plug to 34
Nzm (25 ft. lbs.) torque.
(13) Install a new oil filter.
(14) Fill engine crankcase with the specified
amount and grade of oil (refer to Group 0, Lubrica-
tion and Maintenance).
(15) Connect the negative cable to the battery.
(16) Start the engine and check for any leaks.
Fig. 3 Clearance Measurement
9 - 4 ENGINESJ

(5) Install the lower bearing insert in the bearing
cap. The lower insert must be dry. Place strip of Plas-
tigage across full width of the lower insert at the cen-
ter of bearing cap. Plastigage must not crumble in
use. If brittle, obtain fresh stock.
(6) Install bearing cap and connecting rod on the
journal and tighten nuts to 45 Nzm (33 ft. lbs.)
torque. DO NOT rotate crankshaft. Plastigage will
smear, resulting in inaccurate indication.
(7) Remove the bearing cap and determine amount
of bearing-to-journal clearance by measuring the
width of compressed Plastigage (Fig. 7). Refer to En-
gine Specifications for the proper clearance.Plasti-
gage should indicate the same clearance across
the entire width of the insert. If the clearance
varies, it may be caused by either a tapered
journal, bent connecting rod or foreign mate-
rial trapped between the insert and cap or rod.
(8) If the correct clearance is indicated, replace-
ment of the bearing inserts is not necessary. Remove
the Plastigage from crankshaft journal and bearing
insert. Proceed with installation.
(9) If bearing-to-journal clearance exceeds the spec-
ification, install a pair of 0.0254 mm (0.001 inch) un-
dersize bearing inserts. All the odd size inserts must
be on the bottom. The sizes of the service replace-
ment bearing inserts are stamped on the backs of the
inserts. Measure the clearance as described in the
previous steps.
(10) The clearance is measured with a pair of
0.0254 mm (0.001 inch) undersize bearing inserts in-
stalled. This will determine if two 0.0254 mm (0.001
inch) undersize inserts or another combination isneeded to provide the correct clearance (refer to Con-
necting Rod Bearing Fitting Chart).
FOR EXAMPLE:If the initial clearance was
0.0762 mm (0.003 inch), 0.025 mm (0.001 inch) un-
dersize inserts would reduce the clearance by 0.025
mm (0.001 inch). The clearance would be 0.002 inch
and within specification. A 0.051 mm (0.002 inch) un-
dersize insert would reduce the initial clearance an
additional 0.013 mm (0.0005 inch). The clearance
would then be 0.038 mm (0.0015 inch).
(11) Repeat the Plastigage measurement to verify
your bearing selection prior to final assembly.
(12) Once you have selected the proper insert, in-
stall the insert and cap. Tighten the connecting rod
bolts to 45 Nzm (33 ft. lbs.) torque.
Fig. 7 Measuring Bearing Clearance with Plastigage
CONNECTING ROD BEARING FITTING CHART
J2.5L ENGINE 9 - 41