2002 JEEP GRAND CHEROKEE Diffe

SWITCH
DESCRIPTION
There are two separate switch pods that operate
the speed control system. The steering-wheel-
mounted switches use multiplexed circuits to provide
inputs to the PCM for ON, OFF, RESUME, ACCEL-
ERATE, SET, DECEL and CANCEL modes. Refer to
the owner's manual for more information on speed
control switch functions and setting procedures.
The individual switches cannot be repaired. If one
switch fails, the entire switch module must be
replaced.
OPERATION
When speed control is selected by depressing the
ON, OFF switch, the PCM allows a set speed to be
stored in its RAM for speed control. To store a set
speed, depress the SET switch while the vehicle is
moving at a speed between approximately 35 and 85
mph. In order for the speed control to engage, the
brakes cannot be applied, nor can the gear selector
be indicating the transmission is in Park or Neutral.
The speed control can be disengaged manually by:
²Stepping on the brake pedal
²Depressing the OFF switch
²Depressing the CANCEL switch.
The speed control can be disengaged also by any of
the following conditions:
²An indication of Park or Neutral
²The VSS signal increases at a rate of 10 mph
per second (indicates that the co-efficient of friction
between the road surface and tires is extremely low)
²Depressing the clutch pedal.
²Excessive engine rpm (indicates that the trans-
mission may be in a low gear)
²The VSS signal decreases at a rate of 10 mph
per second (indicates that the vehicle may have
decelerated at an extremely high rate)
²If the actual speed is not within 20 mph of the
set speed
The previous disengagement conditions are pro-
grammed for added safety.
Once the speed control has been disengaged,
depressing the ACCEL switch restores the vehicle to
the target speed that was stored in the PCM's RAM.
NOTE: Depressing the OFF switch will erase the set
speed stored in the PCM's RAM.
If, while the speed control is engaged, the driver
wishes to increase vehicle speed, the PCM is pro-
grammed for an acceleration feature. With the
ACCEL switch held closed, the vehicle accelerates
slowly to the desired speed. The new target speed is
stored in the PCM's RAM when the ACCEL switch isreleased. The PCM also has a9tap-up9feature in
which vehicle speed increases at a rate of approxi-
mately 2 mph for each momentary switch activation
of the ACCEL switch.
The PCM also provides a means to decelerate with-
out disengaging speed control. To decelerate from an
existing recorded target speed, depress and hold the
COAST switch until the desired speed is reached.
Then release the switch. The ON, OFF switch oper-
ates two components: the PCM's ON, OFF input, and
the battery voltage to the brake switch, which powers
the speed control servo.
Multiplexing
The PCM sends out 5 volts through a fixed resistor
and monitors the voltage change between the fixed
resistor and the switches. If none of the switches are
depressed, the PCM will measure 5 volts at the sen-
sor point (open circuit). If a switch with no resistor is
closed, the PCM will measure 0 volts (grounded cir-
cuit). Now, if a resistor is added to a switch, then the
PCM will measure some voltage proportional to the
size of the resistor. By adding a different resistor to
each switch, the PCM will see a different voltage
depending on which switch is pushed.
Another resistor has been added to the 'at rest cir-
cuit' causing the PCM to never see 5 volts. This was
done for diagnostic purposes. If the switch circuit
should open (bad connection), then the PCM will see
the 5 volts and know the circuit is bad. The PCM will
then set an open circuit fault.
REMOVAL
WARNING: BEFORE BEGINNING ANY AIRBAG SYS-
TEM COMPONENT REMOVAL OR INSTALLATION,
REMOVE AND ISOLATE THE NEGATIVE (-) CABLE
FROM THE BATTERY. THIS IS THE ONLY SURE
WAY TO DISABLE THE AIRBAG SYSTEM. THEN
WAIT TWO MINUTES FOR SYSTEM CAPACITOR TO
DISCHARGE BEFORE FURTHER SYSTEM SERVICE.
FAILURE TO DO THIS COULD RESULT IN ACCIDEN-
TAL AIRBAG DEPLOYMENT AND POSSIBLE
INJURY.
(1) Disconnect and isolate negative battery cable.
(2) Remove airbag module. Refer to Group 8M,
Passive Restraint Systems.
(3) Remove electrical connector at switch.
(4) Remove switch-to-steering wheel mounting
screw (Fig. 7) .
(5) Remove switch.
INSTALLATION
(1) Install switch and mounting screw.
(2) Tighten screw to 1.5 N´m (15 in. lbs.) torque.
(3) Install electrical connector to switch.
WJSPEED CONTROL 8P - 7

(2) Check for battery voltage at the fused B(+) fuse
in the JB. If OK, go to Step 3. If not OK, repair the
open B(+) circuit between the JB fuse and the Power
Distribution Center (PDC).
(3) Check the fused ignition switch output (st-run)
fuse in the JB. If OK, go to Step 4. If not OK, repair
the shorted circuit or component and replace the
faulty fuse.
(4) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (st-run) fuse in the JB. If OK, go to Step 5. If
not OK, repair the open fused ignition switch output
(st-run) circuit between the JB fuse and the ignition
switch as required.
(5) Disconnect and isolate the battery negative
cable. Disconnect the instrument panel wire harness
connector for the Sentry Key Immobilizer Module
(SKIM) from the SKIM connector. Check for continu-
ity between the ground circuit of the instrument
panel wire harness connector for the SKIM and a
good ground. There should be continuity. If OK, go to
Step 6. If not OK, repair the open ground circuit.
(6) Reconnect the battery negative cable. Check for
battery voltage at the fused B(+) circuit cavity of the
instrument panel wire harness connector for the
SKIM. If OK, go to Step 7. If not OK, repair the open
fused B(+) circuit between the SKIM and the JB
fuse.
(7) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (st-run) circuit of the instrument panel wire
harness connector for the SKIM. If OK, refer to the
appropriate diagnostic information and use a
DRBIIItscan tool to complete the diagnosis of the
SKIS. If not OK, repair the open fused ignition
switch output (st-run) circuit between the SKIM and
the JB fuse.
SKIS INDICATOR FLASHES OR LIGHTS SOLID FOLLOWING
BULB TEST
A SKIS indicator that flashes following a successful
bulb test indicates that an invalid key has been
detected, or that a key-related fault has been set. A
SKIS indicator that lights solid following a successful
bulb test indicates that the SKIM has detected a sys-
tem malfunction or that the SKIS is inoperative. In
either case, fault information will be stored in the
SKIM memory. For retrieval of this fault information
and further diagnosis of the SKIS, the PCI data bus,
the SKIM message outputs to the instrument cluster,
the SKIM message outputs to the Body Control Mod-
ule (BCM), or the message inputs and outputs
between the SKIM and the Powertrain Control Mod-
ule (PCM), a DRBIIItscan tool and the appropriate
diagnostic information are required. Following are
preliminary troubleshooting guidelines to be followed
during diagnosis using a DRBIIItscan tool:(1) Using the DRBIIItscan tool, read and record
the faults as they exist in the SKIM when you first
begin your diagnosis of the vehicle. It is important to
document these faults because the SKIM does not
differentiate between historical and active faults. If
this problem turns out to be an intermittent condi-
tion, this information may become invaluable to your
diagnosis.
(2) Using the DRBIIItscan tool, erase all of the
faults from the SKIM.
(3) Cycle the ignition switch to the Off position,
then back to the On position.
(4) Using the DRBIIItscan tool, read any faults
that are now present in the SKIM. These are the
active faults.
(5) Using this active fault information, refer to the
proper procedure in the appropriate diagnostic infor-
mation for the additional specific diagnostic steps.
STANDARD PROCEDURE
STANDARD PROCEDURE - SKIS
INITIALIZATION
The Sentry Key Immobilizer System (SKIS) must
be initialized following a Sentry Key Immobilizer
Module (SKIM) replacement. SKIS initialization
requires the use of a DRBIIItscan tool. Initialization
will also require that you have access to the unique
four-digit PIN code that was assigned to the original
SKIM. The PIN codemustbe used to enter the
Secured Access Mode in the SKIM. This PIN number
may be obtained from the vehicle owner, from the
original vehicle invoice, or from the DaimlerChrysler
Customer Center. (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES - STANDARD PRO-
CEDURE - PCM/SKIM PROGRAMMING).
NOTE: If a Powertrain Control Module (PCM) is
replaced on a vehicle equipped with the Sentry Key
Immobilizer System (SKIS), the unique Secret Key
data must be transferred from the Sentry Key
Immobilizer Module (SKIM) to the new PCM using
the PCM replacement procedure. This procedure
also requires the use of a DRBIIITscan tool and the
unique four-digit PIN code to enter the Secured
Access Mode in the SKIM. Refer to the appropriate
diagnostic information for the proper PCM replace-
ment procedures.
STANDARD PROCEDURE - SENTRY KEY
TRANSPONDER PROGRAMMING
All Sentry Keys included with the vehicle are pre-
programmed to work with the Sentry Key Immobi-
lizer System (SKIS) when it is shipped from the
8Q - 6 VEHICLE THEFT SECURITYWJ
VEHICLE THEFT SECURITY (Continued)

²Front Check Valve- The front washer system
check valve is integral to the wye fitting located in
the washer plumbing between the cowl plenum
washer hose and the front washer nozzles, and is
concealed beneath the cowl plenum cover/grille panel
at the base of the windshield.
²Front Washer Nozzle- Two fluidic front
washer nozzles are secured with integral snap fea-
tures to dedicated openings in the cowl plenum cover/
grille panel located near the base of the windshield.
²Front Washer Plumbing- The plumbing for
the front washer system consists of rubber hoses and
molded plastic fittings. The plumbing is routed along
the left side of the engine compartment from the
washer reservoir, and through the dash panel into
the cowl plenum to the front washer nozzle fittings
beneath the cowl plenum cover/grille panel.
²Front Washer Pump/Motor- The front washer
pump/motor unit is located in a dedicated hole on the
lower outboard side of the washer reservoir, behind
the inner fender liner ahead of the left front wheel.
The front washer pump is located ahead of and below
the rear washer pump.
²Front Wiper Arm- The two front wiper arms
are secured with nuts to the threaded studs on the
ends of the two wiper pivot shafts, which extend
through the cowl plenum cover/grille panel located
near the base of the windshield.
²Front Wiper Blade- The two front wiper
blades are secured to the two front wiper arms with
an integral latch, and are parked on the glass near
the bottom of the windshield when the front wiper
system is not in operation.
²Front Wiper Module- The front wiper pivot
shafts are the only visible components of the front
wiper module. The remainder of the module is con-
cealed within the cowl plenum beneath the cowl ple-
num cover/grille panel. The front wiper module
includes the module bracket, four rubber-isolated
wiper module mounts, the front wiper motor, the
wiper motor crank arm, the two wiper drive links,
and the two front wiper pivots.
²Rain Sensor Module- Models equipped with
the optional automatic wiper feature have a Rain
Sensor Module (RSM) located behind a trim cover on
a bracket bonded to the inside surface of the wind-
shield glass, just above the inside rear view mirror
mounting button.
²Right Multi-Function Switch- The right
(wiper) multi-function switch is secured to the right
side of the multi-function switch mounting housing
near the top of the steering column, just below the
steering wheel. Only the control stalk for the right
multi-function switch is visible, while the remainder
of the switch is concealed beneath the steering col-
umn shrouds. The right multi-function switch con-tains all of the switches and control circuitry for both
the front and rear wiper and washer systems.
²Washer Fluid Level Switch- The washer fluid
level switch is located in a dedicated hole near the
center of the forward surface of the washer reservoir,
behind the left front wheel house splash shield.
²Washer Reservoir- The washer reservoir is
concealed between the left inner fender shield and
the left outer fender panel, behind the inner fender
liner and ahead of the left front wheel. The washer
reservoir filler neck is the only visible portion of the
reservoir, and it is accessed from the left front corner
of the engine compartment.
²Wiper High-Low Relay- The wiper high-low
relay is an International Standards Organization
(ISO) micro relay located in the Power Distribution
Center (PDC) in the engine compartment near the
battery.
²Wiper On-Off Relay- The wiper on-off relay is
an International Standards Organization (ISO) micro
relay located in the Power Distribution Center (PDC)
in the engine compartment near the battery.
Hard wired circuitry connects the front wiper and
washer system components to the electrical system of
the vehicle. These hard wired circuits are integral to
several wire harnesses, which are routed throughout
the vehicle and retained by many different methods.
These circuits may be connected to each other, to the
vehicle electrical system and to the front wiper and
washer system components through the use of a com-
bination of soldered splices, splice block connectors,
and many different types of wire harness terminal
connectors and insulators. Refer to the appropriate
wiring information. The wiring information includes
wiring diagrams, proper wire and connector repair
procedures, further details on wire harness routing
and retention, as well as pin-out and location views
for the various wire harness connectors, splices and
grounds.
OPERATING MODES
The components of the front wiper and washer sys-
tem are designed to work in concert to provide the
following operating modes:
²Automatic Wiper- In models equipped with
the optional automatic wiper feature, the internal
circuitry of both the right (wiper) multi-function
switch, the rain sensor module, and the BCM work
in concert to provide an automatic wiper mode with
five sensitivity selections. The BCM tells the Rain
Sensor Module (RSM) when the automatic wiper
mode is selected and the manually selected sensitiv-
ity level, then the rain sensor module tells the BCM
each time enough water droplets have accumulated
within the wipe pattern on the windshield to require
front wiper operation. The BCM then automatically
WJFRONT WIPERS/WASHERS 8R - 3
FRONT WIPERS/WASHERS (Continued)

²Washer Reservoir- The rear washer system
shares a single reservoir with the front washer sys-
tem, but has its own dedicated washer pump/motor
and plumbing. The washer reservoir is concealed
between the left inner fender shield and the left
outer fender panel, behind the inner fender liner and
ahead of the left front wheel. The washer reservoir
filler neck is the only visible portion of the reservoir,
and it is accessed from the left front corner of the
engine compartment.
Features of the rear wiper and washer system
include the following:
²Continuous Wipe Mode- When the right
multi-function switch control sleeve is moved to the
On position, the rear wiper will be operated at a
fixed speed, continual wipe cycle until the switch
sleeve is moved to the Delay or Off positions, until
the ignition switch is turned to the Off position, or
until the liftgate flip-up glass is ajar.
²Intermittent Wipe Mode- When the right
multi-function switch control sleeve is moved to the
Delay position, the rear wiper will be operated in a
fixed interval, intermittent wipe cycle until the
switch sleeve is moved to the On or Off positions,
until the ignition switch is turned to the Off position,
until the liftgate flip-up glass is ajar, or until the
right multi-function switch control stalk is pushed
forward to activate the rear washer system. The
intermittent wipe mode delay time has a fixed delay
interval of about five to eight seconds between
sweeps.
²Washer Mode- When the right multi-function
switch control stalk is pushed forward to activate the
rear washer system, washer fluid will be dispensed
from the washer reservoir onto the liftgate glass
through the rear washer nozzle and the rear wiper
will operate in a fixed cycle (not intermittent) for as
long as the rear washer pump/motor unit remains
energized. When the control stalk is released from
the momentary Wash position, the wipe-after-wash
feature will continue to operate the rear wiper at a
fixed cycle for about three additional wiper sweeps
before returning to the previously selected mode.
Hard wired circuitry connects the rear wiper and
washer system components to the electrical system of
the vehicle. These hard wired circuits are integral to
several wire harnesses, which are routed throughout
the vehicle and retained by many different methods.
These circuits may be connected to each other, to the
vehicle electrical system and to the rear wiper and
washer system components through the use of a com-
bination of soldered splices, splice block connectors,
and many different types of wire harness terminal
connectors and insulators. Refer to the appropriate
wiring information. The wiring information includes
wiring diagrams, proper wire and connector repairprocedures, further details on wire harness routing
and retention, as well as pin-out and location views
for the various wire harness connectors, splices and
grounds.
OPERATION
The rear wiper and washer system is intended to
provide the vehicle operator with a convenient, safe,
and reliable means of maintaining visibility through
the liftgate glass. The various components of this sys-
tem are designed to convert electrical energy pro-
duced by the vehicle electrical system into the
mechanical action of the wiper blade to wipe the out-
side surface of the glass, as well as into the hydraulic
action of the washer system to apply washer fluid
stored in an on-board reservoir to the area of the
glass to be wiped. When combined, these components
provide the means to effectively maintain clear visi-
bility for the vehicle operator by removing excess
accumulations of rain, snow, bugs, mud, or other
minor debris from the outside liftgate glass surface
that might be encountered while driving the vehicle
under numerous types of inclement operating condi-
tions. The vehicle operator initiates all rear wiper
and washer system functions with the right multi-
function switch located on the right side of the steer-
ing column, just below the steering wheel. Moving
the switch control sleeve to a detent position selects
the rear wiper system operating mode. Moving the
switch control stalk forward to a momentary position
activates the rear washer pump/motor, which dis-
penses washer fluid onto the liftgate glass through
the rear washer nozzle and operates the rear wiper
system in the fixed cycle mode for as long as the
washer switch is closed plus about three wiper
sweeps.
When the ignition switch is in the Accessory or On
positions, battery current from a fuse in the Junction
Block (JB) is provided to the right multi-function
switch through a fused ignition switch output (run-
acc) circuit. A separate fuse in the JB provides bat-
tery current to the electronic control circuitry of the
rear wiper module through a fused B(+) circuit.
When the right multi-function switch control sleeve
On position is selected, the On position circuitry
within the switch directs a battery current rear
wiper motor control signal input to the rear wiper
module electronic circuitry, which causes the rear
wiper motor to run at a fixed continuous wipe cycle.
When the right multi-function switch control sleeve
Delay position is selected, the Delay position cir-
cuitry within the switch directs a battery current
rear washer switch output signal input to the rear
wiper module electronic circuitry, which causes the
rear wiper motor to run at a fixed intermittent wipe
cycle. When the right multi-function switch control
8R - 34 REAR WIPERS/WASHERSWJ
REAR WIPERS/WASHERS (Continued)

STANDARD PROCEDURE - TESTING FOR A
SHORT TO GROUND ON FUSES POWERING
SEVERAL LOADS
(1) Refer to the wiring diagrams and disconnect or
isolate all items on the suspected fused circuits.
(2) Replace the blown fuse.
(3) Supply power to the fuse by turning ON the
ignition switch or re-connecting the battery.
(4) Start connecting or energizing the items in the
fuse circuit one at a time. When the fuse blows the
circuit with the short to ground has been isolated.
STANDARD PROCEDURE - TESTING FOR A
VOLTAGE DROP
(1) Connect the positive lead of the voltmeter to
the side of the circuit closest to the battery (Fig. 9).
(2) Connect the other lead of the voltmeter to the
other side of the switch, component or circuit.
(3) Operate the item.
(4) The voltmeter will show the difference in volt-
age between the two points.
SPECIAL TOOLS
WIRING/TERMINAL
Fig. 9 TESTING FOR VOLTAGE DROP
PROBING TOOL PACKAGE 6807
TERMINAL PICK TOOL SET 6680
TERMINAL REMOVING TOOLS 6932 AND 8638
TERMINAL REMOVING TOOL 6934
8W - 01 - 10 8W-01 WIRING DIAGRAM INFORMATIONWJ
WIRING DIAGRAM INFORMATION (Continued)

DIAGNOSIS AND TESTINGÐREAR SEAL AREA
LEAKS
Since it is sometimes difficult to determine the
source of an oil leak in the rear seal area of the
engine, a more involved inspection is necessary. The
following steps should be followed to help pinpoint
the source of the leak.
If the leakage occurs at the crankshaft rear oil seal
area:
(1) Disconnect the battery.
(2) Raise the vehicle.
(3) Remove torque converter or clutch housing
cover and inspect rear of block for evidence of oil.
Use a black light to check for the oil leak:
(a) Circular spray pattern generally indicates
seal leakage or crankshaft damage.
(b) Where leakage tends to run straight down,
possible causes are a porous block, distributor seal,
camshaft bore cup plugs, oil galley pipe plugs, oil
filter runoff, and main bearing cap to cylinder
block mating surfaces.
(4) If no leaks are detected, pressurized the crank-
case as outlined in (Refer to 9 - ENGINE/LUBRICA-
TION - DIAGNOSIS AND TESTING)
CAUTION: Do not exceed 20.6 kPa (3 psi).
(5) If the leak is not detected, very slowly turn the
crankshaft and watch for leakage. If a leak is
detected between the crankshaft and seal while
slowly turning the crankshaft, it is possible the
crankshaft seal surface is damaged. The seal area on
the crankshaft could have minor nicks or scratches
that can be polished out with emery cloth.
CAUTION: Use extreme caution when crankshaft
polishing is necessary to remove minor nicks or
scratches. The crankshaft seal flange is specially
machined to complement the function of the rear oil
seal.
(6) For bubbles that remain steady with shaft
rotation, no further inspection can be done until dis-
assembled. Refer to the service DiagnosisÐMechani-
cal, under the Oil Leak row, for components
inspections on possible causes and corrections.
(7) After the oil leak root cause and appropriate
corrective action have been identified, (Refer to 9 -
ENGINE/ENGINE BLOCK/CRANKSHAFT OIL
SEAL - REAR - REMOVAL), for proper replacement
procedures.
STANDARD PROCEDURE
STANDARD PROCEDURE - FORM-IN-PLACE
GASKETS AND SEALERS
There are numerous places where form-in-place
gaskets are used on the engine. Care must be taken
when applying form-in-place gaskets to assure
obtaining the desired results.Do not use form-in-
place gasket material unless specified.Bead size,
continuity, and location are of great importance. Too
thin a bead can result in leakage while too much can
result in spill-over which can break off and obstruct
fluid feed lines. A continuous bead of the proper
width is essential to obtain a leak-free gasket.
There are numerous types of form-in-place gasket
materials that are used in the engine area. Mopart
Engine RTV GEN II, MopartATF-RTV, and Mopart
Gasket Maker gasket materials, each have different
properties and can not be used in place of the other.
MOPARtENGINE RTV GEN II
MopartEngine RTV GEN II is used to seal com-
ponents exposed to engine oil. This material is a spe-
cially designed black silicone rubber RTV that
retains adhesion and sealing properties when
exposed to engine oil. Moisture in the air causes the
material to cure. This material is available in three
ounce tubes and has a shelf life of one year. After one
year this material will not properly cure. Always
inspect the package for the expiration date before
use.
MOPARtATF RTV
MopartATF RTV is a specifically designed black
silicone rubber RTV that retains adhesion and seal-
ing properties to seal components exposed to auto-
matic transmission fluid, engine coolants, and
moisture. This material is available in three ounce
tubes and has a shelf life of one year. After one year
this material will not properly cure. Always inspect
the package for the expiration date before use.
MOPARtGASKET MAKER
MopartGasket Maker is an anaerobic type gasket
material. The material cures in the absence of air
when squeezed between two metallic surfaces. It will
not cure if left in the uncovered tube. The anaerobic
material is for use between two machined surfaces.
Do not use on flexible metal flanges.
MOPARtGASKET SEALANT
MopartGasket Sealant is a slow drying, perma-
nently soft sealer. This material is recommended for
sealing threaded fittings and gaskets against leakage
of oil and coolant. Can be used on threaded and
machined parts under all temperatures. This mate-
rial is used on engines with multi-layer steel (MLS)
cylinder head gaskets. This material also will pre-
vent corrosion. MopartGasket Sealant is available in
a 13 oz. aerosol can or 4oz./16 oz. can w/applicator.
WJENGINE - 4.0L 9 - 9
ENGINE - 4.0L (Continued)

(3) Control valve seat runout to a maximum of
0.0635 mm (0.0025 in.) (Fig. 16).
VALVE STEM-TO-GUIDE CLEARANCE
MEASUREMENT
PREFERRED METHOD
(1) Remove the valve from the head.
(2) Clean the valve stem guide bore with solvent
and a bristle brush.
(3) Insert a telescoping gauge into the valve stem
guide bore approximately 9.525 mm (.375 inch) from
the valve spring side of the head (Fig. 17).
(4) Remove and measure telescoping gauge with a
micrometer.
(5) Repeat the measurement with contacts length-
wise to engine cylinder head.
(6) Compare the crosswise to lengthwise measure-
ments to determine out-of-roundness. If the measure-
ments differ by more than 0.0635 mm (0.0025 in.),
ream the guide bore to accommodate an oversize
valve stem.
(7) Compare the measured valve guide bore diam-
eter with specifications (7.95-7.97 mm or 0.313-0.314
inch). If the measurement differs from specification
by more than 0.076 mm (0.003 inch), ream the guide
bore to accommodate an oversize valve stem.
ALTERNATIVE METHOD
(1) Use a dial indicator to measure the lateral
movement of the valve stem (stem-to-guide clear-
ance). This must be done with the valve installed in
its guide and just off the valve seat (Fig. 18).
(2) Correct clearance is 0.025-0.0762 mm
(0.001-0.003 inch). If indicated movement exceeds the
specification ream the valve guide to accommodate
an oversize valve stem.
Fig. 14 VALVE AND KEEPER CONFIGURATION 4.0L
1 - VALVE LOCKS (3±BEAD)
2 - RETAINER
3 - VALVE STEM OIL SEAL
4 - INTAKE VALVE
5 - EXHAUST VALVE
6 - VALVE SPRING
Fig. 15 Valve Facing
1 - VALVE MARGIN
2 - NO MARGIN
Fig. 16 Measurement of Valve Seat Runout
1 - DIAL INDICATOR
9 - 24 ENGINE - 4.0LWJ
INTAKE/EXHAUST VALVES & SEATS (Continued)

(2) Remove cap screws, bridge and pivot assem-
blies and rocker arms (Refer to 9 - ENGINE/CYLIN-
DER HEAD/ROCKER ARM / ADJUSTER ASSY -
REMOVAL) for access to each valve spring to be
removed.
(3) Remove push rods.Retain the push rods,
bridges, pivots and rocker arms in the same
order and position as removed.
(4) Inspect the springs and retainer for cracks and
possible signs of weakening.
(5) Remove the spark plug(s) adjacent to the cylin-
der(s) below the valve springs to be removed.
(6) Connect an air hose to the adapter and apply
air pressure slowly. Maintain at least 621 kPa (90
psi) of air pressure in the cylinder to hold the valves
against their seats. For vehicles equipped with an air
conditioner, use a flexible air adaptor when servicing
the No.1 cylinder.
(7) Tap the retainer or tip with a rawhide hammer
to loosen the lock from the retainer. Use Valve Spring
Compressor Tool MD-998772A to compress the spring
and remove the locks (Fig. 27).
(8) Remove valve spring and retainer (Fig. 27).
(9) Remove valve stem oil seals (Fig. 27). Note the
valve seals are different for intake and exhaust
valves. The top of each seal is marked either INT
(intake/black in color) or EXH (exhaust/brown in
color). DO NOT mix the seals.
INSTALLATION
NOTE: This procedure can be done with the engine
cylinder head installed on the block.
CAUTION: Install oil seals carefully to prevent dam-
age from the sharp edges of the valve spring lock
grove.
(1) Lightly push the valve seal over the valve stem
and valve guide boss. Be sure the seal is completely
seated on the valve guide boss.
(2) Install valve spring and retainer (Fig. 28).
(3) Compress the valve spring with Valve Spring
Compressor Tool MD-998772A and insert the valve
locks. Release the spring tension and remove the
tool. Tap the spring from side-to-side to ensure that
the spring is seated properly on the engine cylinder
head.(4) Release air pressure and disconnect the air
hose. Remove the adaptor from the spark plug hole
and install the spark plug.
(5) Repeat the procedures for each remaining valve
spring to be removed.
(6) Install the push rods. Ensure the bottom end of
each rod is centered in the plunger cap seat of the
hydraulic valve tappet.
(7) Install the rocker arms, pivots and bridge
(Refer to 9 - ENGINE/CYLINDER HEAD/ROCKER
ARM / ADJUSTER ASSY - INSTALLATION) at their
original location.
(8) Install the engine cylinder head cover (Refer to
9 - ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - INSTALLATION).
Fig. 27 Valve and Valve Components
1 - VALVE LOCKS (3±BEAD)
2 - RETAINER
3 - VALVE STEM OIL SEAL
4 - INTAKE VALVE
5 - EXHAUST VALVE
6 - VALVE SPRING
WJENGINE - 4.0L 9 - 29
VALVE SPRINGS (Continued)