ESP JEEP CHEROKEE 1994 Service Owner's Manual

(2) Test the sensor output voltage at the sensor
connector between terminals A and B as marked on
the sensor body (Fig. 21). This is done with the igni-
tion switch ON and the engine OFF. Output voltage
should be 4-to-5 volts.The voltage should drop to
1.5-to-2.1 volts with a hot, neutral idle speed con-
dition.
(3) Test Powertrain Control Module (PCM) termi-
nal-1 for the same voltage described above to verify
the wire harness condition. Repair as necessary.
(4) Test sensor supply voltage at sensor connector
between terminals A and C with the ignition ON.
The voltage should be approximately 5 volts (60.5V).
Five volts (60.5V) should also be at terminal-6 of the
corresponding Powertrain Control Module (PCM)
wire harness connector. Repair or replace the wire
harness as necessary.(5) Test the sensor ground circuit at sensor connec-
tor terminal-A and PCM connector terminal-4. Re-
pair the wire harness if necessary.
(6) Test the sensor ground circuit at the PCM con-
nector between terminal-4 and terminal-11 with an
ohmmeter. If the ohmmeter indicates an open circuit,
inspect for a defective sensor ground connection. Re-
fer to Group 8W, Wiring for location of ground con-
nection. If the ground connection is good, replace the
PCM. If terminal-4 has a short circuit to 12 volts,
correct this condition before replacing the PCM.
POWERTRAIN CONTROL MODULE (PCM)
The PCM (formerly called the SBEC or engine con-
troller) is located in the engine compartment behind
the windshield washer fluid tank on YJ models (Fig.
22). It is located in the engine compartment next to
the air cleaner on XJ models (Fig. 23).
The ignition system is controlled by the PCM.
For removal and installation of this component, re-
fer to the Component Removal/Installation section of
this group.
Fig. 20 MAP SensorÐTypical
Fig. 21 MAP Sensor TestÐTypical
Fig. 22 PCM LocationÐYJ Models
Fig. 23 PCM LocationÐXJ Models
JIGNITION SYSTEMS 8D - 15

For diagnostics, refer to the appropriate Powertrain
Diagnostic Procedures service manual for operation
of the DRB scan tool.
SPARK PLUGS
For spark plug removal, cleaning, gap adjustment
and installation, refer to the Component Removal/In-
stallation section of this group.
Faulty carbon and/or gas fouled plugs generally
cause hard starting, but they will clean up at higher
engine speeds. Faulty plugs can be identified in a
number of ways: poor fuel economy, power loss, de-
crease in engine speed, hard starting and, in general,
poor engine performance.
Remove the spark plugs and examine them for
burned electrodes and fouled, cracked or broken por-
celain insulators. Keep plugs arranged in the order
in which they were removed from the engine. An iso-
lated plug displaying an abnormal condition indi-
cates that a problem exists in the corresponding
cylinder. Replace spark plugs at the intervals recom-
mended in the maintenance chart in Group 0, Lubri-
cation and Maintenance.
Spark plugs that have low mileage may be cleaned
and reused if not otherwise defective. Refer to the
following Spark Plug Condition section of this group.
CONDITION
NORMAL OPERATING
The few deposits present on the spark plug will
probably be light tan or slightly gray in color. This is
evident with most grades of commercial gasoline
(Fig. 24). There will not be evidence of electrode
burning. Gap growth will not average more than ap-
proximately 0.025 mm (.001 in) per 1600 km (1000
miles) of operation. Spark plugs that have normal
wear can usually be cleaned, have the electrodes
filed, have the gap set and then be installed.Some fuel refiners in several areas of the United
States have introduced a manganese additive (MMT)
for unleaded fuel. During combustion, fuel with
MMT causes the entire tip of the spark plug to be
coated with a rust colored deposit. This rust color can
be misdiagnosed as being caused by coolant in the
combustion chamber. Spark plug performance is not
affected by MMT deposits.
COLD FOULING/CARBON FOULING
Cold fouling is sometimes referred to as carbon
fouling. The deposits that cause cold fouling are ba-
sically carbon (Fig. 24). A dry, black deposit on one
or two plugs in a set may be caused by sticking
valves or defective spark plug cables. Cold (carbon)
fouling of the entire set of spark plugs may be caused
by a clogged air filter or repeated short operating
times (short trips).
ELECTRODE GAP BRIDGING
Electrode gap bridging may be traced to loose de-
posits in the combustion chamber. These deposits ac-
cumulate on the spark plugs during continuous stop-
and-go driving. When the engine is suddenly
subjected to a high torque load, deposits partially liq-
uefy and bridge the gap between electrodes (Fig. 25).
This short circuits the electrodes. Spark plugs with
electrode gap bridging can be cleaned using standard
procedures.
SCAVENGER DEPOSITS
Fuel scavenger deposits may be either white or yel-
low (Fig. 26). They may appear to be harmful, but
this is a normal condition caused by chemical addi-
tives in certain fuels. These additives are designed to
change the chemical nature of deposits and decrease
spark plug misfire tendencies. Notice that accumula-
tion on the ground electrode and shell area may be
heavy, but the deposits are easily removed. Spark
Fig. 24 Normal Operation and Cold (Carbon) Fouling
Fig. 25 Electrode Gap Bridging
8D - 16 IGNITION SYSTEMSJ

Check the high-tension cable connections for good
contact at the ignition coil, distributor cap towers
and spark plugs. Terminals should be fully seated.
The terminals and spark plug covers should be in
good condition. Terminals should fit tightly to the ig-
nition coil, distributor cap and spark plugs. The
spark plug cover (boot) of the cable should fit tight
around the spark plug insulator. Loose cable connec-
tions can cause corrosion and increase resistance, re-
sulting in shorter cable service life.
Clean the high tension cables with a cloth moist-
ened with a nonflammable solvent and wipe dry.
Check for brittle or cracked insulation.
When testing secondary cables for damage with an
oscilloscope, follow the instructions of the equipment
manufacturer.
If an oscilloscope is not available, spark plug cables
may be tested as follows:
CAUTION: Do not leave any one spark plug cable
disconnected for longer than necessary during test-
ing. This may cause possible heat damage to the
catalytic converter. Total test time must not exceed
ten minutes.
With the engine not running, connect one end of a
test probe to a good ground. Start the engine and run
the other end of the test probe along the entire
length of all spark plug cables. If cables are cracked
or punctured, there will be a noticeable spark jump
from the damaged area to the test probe. The cable
running from the ignition coil to the distributor cap
can be checked in the same manner. Cracked, dam-
aged or faulty cables should be replaced with resis-
tance type cable. This can be identified by the words
ELECTRONIC SUPPRESSION printed on the cable
jacket.
Use an ohmmeter to test for open circuits, exces-
sive resistance or loose terminals. Remove the dis-
tributor cap from the distributor.Do not remove
cables from cap.Remove cable from spark plug.
Connect ohmmeter to spark plug terminal end of ca-
ble and to corresponding electrode in distributor cap.
Resistance should be 250 to 1000 Ohms per inch of
cable. If not, remove cable from distributor cap tower
and connect ohmmeter to the terminal ends of cable.
If resistance is not within specifications as found in
the Spark Plug Cable Resistance chart, replace the
cable. Test all spark plug cables in this manner.To test ignition coil-to-distributor cap cable, do not
remove the cable from the cap. Connect ohmmeter to
rotor button (center contact) of distributor cap and
terminal at ignition coil end of cable. If resistance is
not within specifications as found in the Spark Plug
Cable Resistance chart, remove the cable from the
distributor cap. Connect the ohmmeter to the termi-
nal ends of the cable. If resistance is not within spec-
ifications as found in the Spark Plug Cable
Resistance chart, replace the cable. Inspect the igni-
tion coil tower for cracks, burns or corrosion.
For removal and installation of spark plug cables,
refer to Spark Plug Secondary Cables in the Compo-
nent Removal/Installation section.
THROTTLE POSITION SENSOR TEST
To perform a complete test of this sensor and its
circuitry, refer to the DRB scan tool. Also refer to the
appropriate Powertrain Diagnostics Procedures man-
ual. To test the sensor only, refer to the following:
The throttle position sensor can be tested with a
digital voltmeter. The center terminal of the sensor
connector is the output terminal (Figs. 30 or 31).
SPARK PLUG CABLE RESISTANCE
Fig. 30 SensorÐ2.5L Engine
Fig. 31 SensorÐ4.0L Engine
8D - 18 IGNITION SYSTEMSJ

GAUGE PACKAGE GENERAL INFORMATION
The gauge package contains 4 gauges and the 4
wheel drive indicator. The gauges have a common
battery feed from fuse #9 and ignition switch. Al-
though they have separate power sources, the 4
gauges share a common ground connection.
The voltmeter indicates electrical system voltage.
When the engine is not running, the voltage regis-
tered is from the battery. After the engine is started,
charging system voltage is indicated. In the gauge
package, the voltmeter forms a parallel connectionacross the battery feed and ground.
The remaining gauges - oil pressure, fuel and cool-
ant temperature - are connected to individual sender
units. Variable resistors in the senders will change
the amount of current allowed to flow through the
gauge coils. As current flow through the coils varies,
the position of the indicator needle also will vary.
The 4 gauges are connected to battery feed, ground
and the sender units through a printed circuit
mounted on the back of the gauge housing.
GAUGE PACKAGE DIAGNOSIS
ALL GAUGES INOPERATIVE (Fig. 15)
(1) Check the fuse #9. Replace as required.
(2) Turn ignition switch to ON and measure volt-
age at battery side of fuse #9. Meter should read bat-
tery voltage. If not, repair open from ignition switch.
(3) Unplug gauge package connector from gauge
package.
(4) Turn ignition switch to OFF and measure resis-
tance from instrument cluster connector terminals 1
and 13 to a clean chassis ground. Meter should read
zero ohms. If not, repair open to ground.
(5) Turn ignition switch to ON and measure volt-
age at instrument cluster connector terminals 2 and
12. Meter should read battery voltage. If not, repair
open from fuse panel.
ONE GAUGE INOPERATIVE
Does not apply to voltmeter.
OIL PRESSURE SENDER
(1) Turn ignition switch to ON.
(2) Unplug oil pressure sender connector from oil
pressure sender.
(3) Touch connector to engine block (ground).
Gauge should read at low end of scale.
(4) When connector is NOT touching ground (open
circuit) gauge should read at high end of scale. If OK
replace sender. If not, proceed with step 5.
(5) Check circuit between sender and gauge for an
open. Repair as required. If wiring is OK, replace
gauge.
COOLANT TEMPERATURE SENDER
(1) Turn ignition switch to ON.
(2) Unplug coolant temperature sender connector
from coolant temperature sender.
(3) Touch connector to engine block (ground).
Gauge should read at high end of scale.
(4) When connector is NOT touching ground (open
circuit) gauge should read at low end of scale. If OK
replace sender. If not, proceed with step 5.
(5) Check circuit between sender and gauge for an
open. Repair as required. If wiring is OK, replace
gauge.
FUEL GAUGE SENDER
(1) Turn ignition switch to ON.
(2) Separate fuel gauge sender connector from fuel
gauge sender near tank.
(3) Ground the center wire of the body harness
side of the connector. The gauge should read at low
end of scale. If OK, check sending unit (step 4). If
not, check circuit between connector and gauge. Re-
pair as required. If circuit is OK, replace gauge.
(4) Turn ignition switch to OFF.
(5) Measure resistance from fuel gauge sender con-
nector center terminal to a clean chassis ground.
Meter readings should correspond to those shown in
Specifications. If not OK, replace sender. If OK, re-
pair open from fuel gauge sender connector to
ground.
PRINTED CIRCUIT
(1) Turn ignition switch to ON.
(2) Unplug gauge package connector from gauge
package.
(3) Measure resistance from gauge package termi-
nal 12 (fuel and coolant temperature gauge) or from
terminal 2 (voltmeter and oil pressure gauge) to
gauge battery terminal. Meter should read zero
ohms. If not, replace/repair printed circuit.
(4) Measure resistance from gauge package termi-
nal 13 (fuel and coolant temperature gauge) or from
terminal 1 (voltmeter and oil pressure gauge) to
gauge ground terminal. Meter should read zero
ohms. If not, replace/repair printed circuit. If zero
ohms, replace gauge.
GAUGE CALIBRATION VALUES
Use the charts in Specifications. The calibration of
the gauge can be checked. If the indicator needle is
not in the correct position, replace the gauge.
4WD INDICATOR
The four-wheel drive indicator lamp circuit is com-
pleted by the Command-Trac switch located below
the battery.
8E - 22 YJ INSTRUMENT PANEL AND GAUGESJ

TO RESUME AFTER BRAKING:After disen-
gaging the speed control system by tapping the brake
pedal or clutch pedal, push the RESUME/ACCEL
button to return vehicle to the previously set speed.
SET/COAST:Speed can be decreased by holding
SET button against stop until desired speed is at-
tained. Releasing the button engages the system at
that speed. A decrease in speed also can be attained
by tapping brake pedal lightly disengaging system.
When desired speed has been obtained push and re-
lease SET button.
TO ACCELERATE FOR PASSING:Depress ac-
celerator as needed. When passing is completed, re-lease accelerator and vehicle will return to previous
speed setting. There may be a slight (3-7 mph) speed
loss before the vehicle recovers to the set speed.
TAP-UP:When the speed control system is en-
gaged, tapping the RESUME/ACCEL button will in-
crease the speed setting by 2 mph (3 km/h). The
system will respond to multiple tap-ups.
TO ACCELERATE:While speed control is en-
gaged, hold the RESUME/ACCEL button depressed
and release at a new desired speed. This will allow
the vehicle to accelerate and set at a higher speed
setting.
8H - 2 VEHICLE SPEED CONTROL SYSTEMJ

perform the speed control switch test. If switch is not
at fault, then check main harness and repair as nec-
essary.
(8) Using an ohmmeter, connect one lead to a good
body ground and touch other lead to terminal in cav-
ity number 29. With brake pedal released, meter
should show continuity. When pedal is depressed,
meter should show open circuit.
SPEED CONTROL SWITCH (TURN SIGNAL LEVER)
TEST
STOP LAMP SPEED CONTROL SWITCH TEST
(1) Disconnect double connector at switch pigtail
and connect a 12 volt source to either terminal. Con-
nect a test lamp between other terminal and a good
ground. The test lamp should be on when brakepedal is in normal position. The test light should go
off when brake pedal is depressed approximately 3/8
of an inch.
(2) If test lamp does not respond properly, the stop
lamp switch is defective or out of adjustment.
(3) Stop lamp switch adjustment is detailed in
Group 5 - Brakes section of this manual.
VACUUM SUPPLY TEST
(1) Disconnect vacuum hose at servo or vacuum
reservoir and install a vacuum gauge in hose (Fig.
6).
(2) Start engine and observe gauge at idle. Vac-
uum gauge should read at least ten inches of mer-
cury.
(3) If vacuum does not meet this requirement,
check for vacuum leaks or poor engine performance.
OPERATIONAL CHECK (ROAD TEST)
The following sequential checks are performed with
the speed switch ON and vehicle speed faster than 35
mph:
(1) Press the SET button in end of multi-function
lever. Vehicle should maintain set speed.
(2) Hold SET button in, and remove foot from ac-
celerator. Vehicle should coast to a slower speed.
(3) Release SET button. Speed control will engage
and hold a slower speed, provided the speed remains
above 35 mph.
JVEHICLE SPEED CONTROL SYSTEM 8H - 7

CAUTION: DO NOT move the wiper switch to DE-
LAY with the intermittent wiper module removed
from the circuit. If the switch is moved to the DE-
LAY position during the next step, the switch will
be damaged.
²Test wiper operation in LOW and HIGH speed
modes, and test washer operation. If these modes
were inoperative, but are OK now, replace failed in-
termittent wiper module.
(4) To test the wiper/washer switch, see Wiper
Switch Testing. Turn ignition switch to OFF. Posi-
tion the wiper switch as indicated, and back probe
switch side of wiper switch connector. If switch tests
OK, go to step 5. If not, replace switch and go to step
6.
(5) To further test the wiper/washer switch, turn
ignition switch to ACCESSORY or ON. Position the
wiper switch as indicated in the tests below, and
back probe switch side of wiper switch connector.
²Measure voltage at terminal E with wiper switch
in LOW, MIST and with washer switch depressed.
Meter should read battery voltage. If not, replace
switch.
²Measure voltage at connector terminal C with
wiper switch in HIGH. Meter should read battery
voltage. If not, replace switch.
²With wiper switch in LOW or HIGH, measure
voltage at connector terminal F, then move wiper
switch to OFF. Meter shold read battery voltage un-
til wipers park and then zero volts. If OK, go to step
6. If not, check wiring to wiper motor, then go to step
6.
(6) To test the wiper motor, turn the ignition
switch to ACCESSORY or ON. Position the wiper
switch and back probe the motor connector as indi-
cated.
²Wiper switch in any position, measure voltage at
terminal B. Meter should read battery voltage. If not,
repair wiring from circuit breaker.
²Wiper switch in LOW, measure voltage at termi-
nal A. Meter should read battery voltage. If OK, but
wipers do not operate, replace failed wiper motor. If
not, repair wiring from switch or intermittent wiper
module connector.
²Wiper switch in HIGH, measure voltage at termi-
nal H. Meter should read battery voltage. If OK, but
wipers do not operate, replace failed wiper motor. If
not, repair wiring from switch or intermittent wiper
module connector.
²Wiper switch in LOW or HIGH, voltmeter con-
nected to terminal D. Turn wiper switch to OFF and
observe meter. Meter should read battery voltage
when switch goes to OFF, then zero volts after wip-
ers park. If battery voltage is present, but wipers fail
to park; or, if no battery voltage present, replace
failed wiper motor.DIAGNOSING NON-INTERMITTENT WINDSHIELD
WASHER
Refer to Group 8W - Wiring Diagrams.
(1) Measure resistance from washer pump connec-
tor terminal B to a clean chassis ground. Meter
should read zero ohms. If not, repair open between
terminal B and ground.
(2) Turn ignition switch to ON and press washer
switch.
²Measure voltage at switch connector terminal B.
Meter should read battery voltage. If not, replace
wiper/washer switch.
²Measure voltage at washer pump connector termi-
nal A. Meter should read battery voltage. If OK, re-
place pump. If not, repair open between switch
connector and pump connector.
DIAGNOSING INTERMITTENT WINDSHIELD
WASHER
Refer to Group 8W - Wiring Diagrams.
(1) Measure resistance from washer pump connec-
tor terminal B to a clean chassis ground. Meter
should read zero ohms. If not, repair open between
terminal B and ground.
(2) Turn ignition switch to ON and rotate washer
switch tab forward.
²Measure voltage at wiper/washer switch connector
terminal B located at intermittent wipe module.
Meter should read battery voltage. If not, replace
wiper switch.
²Measure voltage at intermittent wipe module con-
nector terminal B (to washer pump). Meter should
read battery voltage. If not, replace intermittent
wipe module.
²Measure voltage at washer pump connector termi-
nal A. Meter should read battery voltage. If OK, re-
place pump. If not, repair open from intermittent
wipe module connector terminal B.
REAR WIPER ARM REPLACEMENT
(1) Install wiper arm remover, Snap On A192 or
equivalent, on wiper arm (Fig. 11). Lift arm and then
remove from pivot shaft.
CAUTION: Do not use a screwdriver or other prying
tool to remove an arm. This may distort it in a way
that will allow it to come off the pivot shaft in the
future, despite how carefully it is installed. NEVER
push or bend the spring clip in the base of the arm
in an attempt to release the arm. This clip is self re-
leasing.
(2) To install, reverse the removal procedure.
(3) Wet the window and check the park position by
operating the wiper motor several times.
8K - 12 WINDSHIELD WIPERSJ

(5) Remove latch.
(6) Drill out 2 rivets and remove solenoid.
(7) To install solenoid, reverse the removal proce-
dures.
(8) Tighten latch screws to 9 Nzm (7 ft. lbs.) torque.
KEYLESS ENTRY
INDEX
page page
Diagnosing Power Door Locks............... 9
Door Lock/Unlock Relay Replacement......... 12
Receiver................................ 8
Receiver Service......................... 11
System Description........................ 8System Operation......................... 9
Transmitter.............................. 8
Transmitter Programming................... 9
Transmitter Service........................ 9
SYSTEM DESCRIPTION
The keyless entry system consists of a portable re-
mote control transmitter and a receiver mounted in
the overhead console or between the sun visors. Sys-
tem operation is based on a coded infrared signal
from the transmitter to the receiver. The transmitter
is programmed into the receiver providing the correct
programming sequence is met.
When the keyless entry system is activated, the cor-
responding relay operates to supply voltage to the mo-
tors. The use of either relay determines the polarity of
the voltage that is supplied to the door lock motors.
When the keyless entry system is used, the trans-
mitter sends a signal to the keyless entry module. If
the doors are unlocked, the module activates a tran-
sistor switch to apply voltage to the lock relay coil.
The coil is energized to close the normally open con-
tacts of the lock relay. Battery voltage from the relay
is applied to the door lock motors to lock the doors.
Current flows in the same path to ground as it does
when the master door lock switch is used.When the doors are locked, the keyless entry mod-
ule applies voltage to the unlock relay coil and a
similar action takes places to unlock the doors.
TRANSMITTER
The pocket size, solid state transmitter operates on
(2) 3-volt lithium (CR1616) batteries (Fig. 1). The
transmitter is activated by pressing either the LOCK
or UNLOCK button. This closes the internal contacts
that complete the battery circuit.
The battery voltage activates the transmitter diode
which in turn generates a coded infrared signal. The
signal is transmitted as pulses of infrared light.
If the red LED on the side of the transmitter does
not light when the transmitter is activated, the bat-
teries are low.
RECEIVER
The receiver is in circuit with the electric door lock
system. The coded infrared signal is picked up by the
receiver diode and is shaped, amplified and decoded by
an integrated circuit within the receiver. If the signal
Fig. 10 Latch Assembly Removal/Installation
8P - 8 POWER DOOR LOCKSJ

(3) Connect the CCV hoses (Fig. 1).
(4) Connect negative cable to battery.
ROCKER ARMS
This procedure can be done with the engine in or
out of the vehicle.
REMOVAL
(1) Remove the engine cylinder head cover.
(2) Remove the capscrews at each bridge and pivot
assembly (Fig. 2). Alternately loosen the capscrews
one turn at a time to avoid damaging the bridges.
(3) Check for rocker arm bridges which are caus-
ing misalignment of the rocker arm to valve tip area.
(4) Remove the bridges, pivots and corresponding
pairs of rocker arms (Fig. 2). Place them on a bench
in the same order as removed.
(5) Remove the push rods and place them on a
bench in the same order as removed.
CLEANING
Clean all the components with cleaning solvent.
Use compressed air to blow out the oil passages in
the rocker arms and push rods.
INSPECTION
Inspect the pivot surface area of each rocker arm.
Replace any that are scuffed, pitted, cracked or ex-
cessively worn.
Inspect the valve stem tip contact surface of each
rocker arm and replace any rocker arm that is deeply
pitted.
Inspect each push rod end for excessive wear and
replace as required. If any push rod is excessivelyworn because of lack of oil, replace it and inspect the
corresponding hydraulic tappet for excessive wear.
Inspect the push rods for straightness by rolling
them on a flat surface or by shining a light between
the push rod and the flat surface.
A wear pattern along the length of the push rod is
not normal. Inspect the engine cylinder head for ob-
struction if this condition exists.
INSTALLATION
(1) Lubricate the ball ends of the push rods with
Mopar Engine Oil Supplement, or equivalent and in-
stall push rods in their original locations. Ensure
that the bottom end of each push rod is centered in
the tappet plunger cap seat.
(2) Using Mopar Engine Oil Supplement, or equiv-
alent, lubricate the area of the rocker arm that the
pivot contacts. Install rocker arms, pivots and bridge
above each cylinder in their originally position.
(3) Loosely install the capscrews through each
bridge.
(4) At each bridge, tighten the capscrews alter-
nately, one turn at a time, to avoid damaging the
bridge. Tighten the capscrews to 28 Nzm (21 ft. lbs.)
torque.
(5) Install the engine cylinder head cover.
ENGINE CYLINDER HEAD
This procedure can be done with the engine in or
out of the vehicle.
REMOVAL
(1) Disconnect negative cable from battery.
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAIN COCK WITH THE SYSTEM HOT AND PRES-
SURIZED BECAUSE SERIOUS BURNS FROM THE
COOLANT CAN OCCUR.
(2) Drain the coolant and disconnect the hoses at
the engine thermostat housing. DO NOT waste reus-
able coolant. If the solution is clean and is being
drained only to service the engine or cooling system,
drain the coolant into a clean container for reuse.
(3) Remove the air cleaner assembly.
(4) Remove the engine cylinder head cover.
(5) Remove the capscrews, bridge and pivot assem-
blies and rocker arms (Fig. 2).
(6) Remove the push rods (Fig. 2).Retain the
push rods, bridges, pivots and rocker arms in
the same order as removed.
(7) Loosen the serpentine drive belt at the power
steering pump, if equipped or at the idler pulley (re-
fer to Group 7, Cooling System for the proper proce-
dure).
(8) If equipped with air conditioning, perform the
following:
Fig. 2 Rocker Arm Assembly
J2.5L ENGINE 9 - 19

REMOVAL
Each valve spring is held in place by a retainer
and a set of conical valve locks. The locks can be re-
moved only by compressing the valve spring.
(1) Remove the engine cylinder head cover.
(2) Remove capscrews, bridge and pivot assemblies
and rocker arms 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) Install a 14 mm (1/2 inch) (thread size) air hose
adaptor in the spark plug hole.
(7) 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.
(8) 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. 7).
(9) Remove valve spring and retainer (Fig. 7).
(10) Remove valve stem oil seals (Fig. 7). Note the
valve seals are different for intake and exhaust
valves. The top of each seal is marked either INT
(Intake) or EXH (Exhaust). DO NOT mix the seals.
INSPECTION
Inspect the valve stems, especially the grooves. An
Arkansas smooth stone should be used to remove
nicks and high spots.
INSTALLATION
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.
(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) 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 at
their original location.
(8) Tighten the bridge capscrews alternately, one
at a time, to avoid damaging the bridge. Tighten the
capscrews to 28 Nzm (21 ft. lbs.) torque.
(9) Install the engine cylinder head cover.
VALVES AND VALVE SPRINGS
This procedure is done with the engine cylinder
head removed from the block.
REMOVAL
(1) Remove the engine cylinder head from the cyl-
inder block.
(2) Use Valve Spring Compressor Tool
MD-998772A and compress each valve spring.
(3) Remove the valve locks, retainers, springs and
valve stem oil seals. Discard the oil seals.
(4) Use an Arkansas smooth stone or a jewelers
file to remove any burrs on the top of the valve stem,
especially around the groove for the locks.
(5) Remove the valves, and place them in a rack in
the same order as removed.
VALVE CLEANING
Clean all carbon deposits from the combustion
chambers, valve ports, valve stems, valve stem
guides and head.
Clean all grime and gasket material from the en-
gine cylinder head machined gasket surface.
Fig. 7 Valve and Valve Components
9 - 22 2.5L ENGINEJ