Vin JEEP GRAND CHEROKEE 2002 WJ / 2.G Workshop Manual

REMOVAL
The overdrive unit can be removed and serviced
separately. It is not necessary to remove the entire
transmission assembly to perform overdrive unit
repairs.
If only the overdrive unit requires service, refer to
Overdrive Removal for proper procedures.
CAUTION: The transmission and torque converter
must be removed as an assembly to avoid compo-
nent damage. The converter driveplate, pump bush-
ing, or oil seal can be damaged if the converter is
left attached to the driveplate during removal. Be
sure to remove the transmission and converter as
an assembly.
(1) Disconnect battery negative cable.
(2) Disconnect and lower or remove necessary
exhaust components.
(3) Disconnect fluid cooler lines at transmission.
(4) Remove starter motor. (Refer to 8 - ELECTRI-
CAL/STARTING/STARTER MOTOR - REMOVAL)
(5) Disconnect and remove crankshaft position sen-
sor. (Refer to 14 - FUEL SYSTEM/FUEL INJEC-
TION/CRANKSHAFT POSITION SENSOR -
REMOVAL) Retain sensor attaching bolts.
CAUTION: The crankshaft position sensor will be
damaged if the transmission is removed, or
installed, while the sensor is still bolted to the
engine block, or transmission (4.0L only). To avoid
damage, be sure to remove the sensor before
removing the transmission.
(6) Remove the bolts holding the bell housing
brace to the transmission.
(7) Remove nut holding the bell housing brace to
the engine to transmission bending brace.
(8) Remove the bell housing brace from the trans-
mission (Fig. 13).
(9) Remove the bolt holding the torque converter
cover to the transmission.
(10) Remove the torque converter cover from the
transmission.
(11) If transmission is being removed for overhaul,
remove transmission oil pan, drain fluid and reinstall
pan.
(12) Remove fill tube bracket bolts and pull tube
out of transmission. Retain fill tube seal. On4x4
models, it will also be necessary to remove bolt
attaching transfer case vent tube to converter hous-
ing.
(13) Rotate crankshaft in clockwise direction until
converter bolts are accessible. Then remove bolts one
at a time. Rotate crankshaft with socket wrench on
dampener bolt.(14) Mark propeller shaft and axle yokes for
assembly alignment. Then disconnect and remove
propeller shaft. On4x4models, remove both propel-
ler shafts.
(15) Disconnect wires from park/neutral position
switch and transmission solenoid.
(16) Disconnect gearshift cable from transmission
manual valve lever (Fig. 14).
Fig. 13 Bell Housing Brace and Converter Cover
1 - Transmission
2 - Torque Converter Cover
3 - Bellhousing Brace
Fig. 14 Transmission Shift Cable
1 - SHIFT CABLE
2 - MANUAL LEVER
3 - MANUAL LEVER
WJAUTOMATIC TRANSMISSION - 42RE 21 - 27
AUTOMATIC TRANSMISSION - 42RE (Continued)

(18) Squeeze front band together and remove band
strut (Fig. 27).
(19) Remove front band lever (Fig. 28).
(20) Remove front band lever shaft plug, if neces-
sary, from converter housing.
(21) Remove front band lever shaft.
(22) Remove front and rear clutch units as assem-
bly. Grasp input shaft, hold clutch units together and
remove them from case (Fig. 29).
(23) Lift front clutch off rear clutch (Fig. 30). Set
clutch units aside for overhaul.(24) Remove intermediate shaft thrust washer
from front end of shaft or from rear clutch hub (Fig.
31).
(25) Remove output shaft thrust plate from inter-
mediate shaft hub (Fig. 32).
(26) Slide front band off driving shell (Fig. 33) and
remove band from case.
Fig. 26 Removing Oil Pump And Reaction Shaft
Support Assembly
1 - OIL PUMP AND REACTION SHAFT SUPPORT ASSEMBLY
2 - SLIDE HAMMER TOOLS C-3752
Fig. 27 Removing Front Band Strut
1 - BAND LEVER
2 - BAND STRUT
3 - FRONT BAND
Fig. 28 Removing Front Band Lever
1 - FRONT BAND LEVER
Fig. 29 Removing Front/Rear Clutch Assemblies
1 - INPUT SHAFT
2 - FRONT CLUTCH
3 - REAR CLUTCH
WJAUTOMATIC TRANSMISSION - 42RE 21 - 31
AUTOMATIC TRANSMISSION - 42RE (Continued)

(27) Remove planetary geartrain as assembly (Fig.
34). Support geartrain with both hands during
removal. Do not allow machined surfaces on interme-
diate shaft or overdrive piston retainer to become
nicked or scratched.
(28) If overdrive unit is not to be serviced, install
Alignment Shaft 6227-2 into the overdrive unit to
prevent misalignment of the overdrive clutches dur-
ing service of main transmission components.
Fig. 30 Separating Front/Rear Clutch Assemblies
1 - FRONT CLUTCH
2 - REAR CLUTCH
Fig. 31 Removing Intermediate Shaft Thrust Washer
1 - INTERMEDIATE SHAFT THRUST WASHER
2 - INPUT SHAFT
3 - REAR CLUTCH RETAINER HUB
Fig. 32 Removing Intermediate Shaft Thrust Plate
1 - INTERMEDIATE SHAFT HUB
2 - INTERMEDIATE SHAFT THRUST PLATE
Fig. 33 Front Band Removal
1 - DRIVING SHELL
2 - FRONT BAND
21 - 32 AUTOMATIC TRANSMISSION - 42REWJ
AUTOMATIC TRANSMISSION - 42RE (Continued)

(29) Loosen rear band adjusting screw 4-5 turns.
(30) Remove low-reverse drum snap-ring (Fig. 35).(31) Remove low-reverse drum and reverse band.
(32) Remove overrunning clutch roller and spring
assembly as a unit (Fig. 36).
(33) Compress front servo rod guide about 1/8 inch
with Valve Spring Compressor C-3422-B (Fig. 37).
(34) Remove front servo rod guide snap-ring. Exer-
cise caution when removing snap-ring. Servo bore
can be scratched or nicked if care is not exercised.
(35) Remove compressor tools and remove front
servo rod guide, spring and servo piston.
Fig. 34 Removing Planetary Geartrain And
Intermediate Shaft Assembly
1 - PLANETARY GEARTRAIN AND INTERMEDIATE SHAFT
ASSEMBLY
Fig. 35 Removing Low-Reverse Drum Snap-Ring
1 - LOW-REVERSE DRUM
2 - HUB OF OVERDRIVE PISTON RETAINER
3 - LOW-REVERSE DRUM SNAP-RING
Fig. 36 Overrunning Clutch Assembly Removal
1 - OVERRUNNING CLUTCH CAM
2 - REAR BAND REACTION PIN
3 - OVERRUNNING CLUTCH ASSEMBLY
Fig. 37 Compressing Front Servo Rod Guide
1 - SPRING COMPRESSOR TOOL C-3422-B
2 - ROD GUIDE SNAP-RING
WJAUTOMATIC TRANSMISSION - 42RE 21 - 33
AUTOMATIC TRANSMISSION - 42RE (Continued)

(15) Align drive teeth on rear clutch discs with
small screwdriver (Fig. 52). This makes installation
on front planetary easier.
(16) Raise front end of transmission upward as far
as possible and support case with wood blocks. Front/
rear clutch and oil pump assemblies are easier to
install if transmission is as close to upright position
as possible.
(17) Slide front band into case.
(18) Install front and rear clutch units as assembly
(Fig. 53). Align rear clutch with front annulus gear
and install assembly in driving shell. Be sure output
shaft thrust washer and thrust plate are not dis-
placed during installation.
(19) Carefully work assembled clutches back and
forth to engage and seat rear clutch discs on front
annulus gear. Also be sure front clutch drive lugs are
fully engaged in slots of driving shell after installa-
tion.
(20) Assemble front band strut.
(21) Install front band adjuster, strut and adjust-
ing screw (Fig. 54).
(22) Tighten band adjusting screw until band just
grips clutch retainer. Verify that front/rear clutches
are still seated before continuing.
Fig. 50 Assembling Front And Rear Clutch Units
1 - TURN FRONT CLUTCH BACK & FORTH UNTIL SEATED
2 - REAR CLUTCH ASSEMBLY
Fig. 51 Installing Intermediate Shaft Thrust Washer
1 - INTERMEDIATE SHAFT THRUST WASHER
2 - INPUT SHAFT
3 - REAR CLUTCH RETAINER HUB
Fig. 52 Aligning Rear Clutch Disc Lugs
1 - REAR CLUTCH DISCS
2 - USE SMALL SCREWDRIVER TO ALIGN CLUTCH DISC
TEETH
21 - 38 AUTOMATIC TRANSMISSION - 42REWJ
AUTOMATIC TRANSMISSION - 42RE (Continued)

BANDS
DESCRIPTION
KICKDOWN (FRONT) BAND
The kickdown, or ªfrontº, band (Fig. 67) holds the
common sun gear of the planetary gear sets. The
front (kickdown) band is made of steel, and faced on
its inner circumference with a friction-type lining.
One end of the band is anchored to the transmissioncase, and the other is acted on with a pushing force
by a servo piston. The front band is a single-wrap
design (the band does not completely encompass/
wrap the drum that it holds).
LOW/REVERSE (REAR) BAND
The low/reverse band, or ªrearº, band (Fig. 68) is
similar in appearance and operation to the front
band. The rear band is slightly different in that it
does not use a link bar, but is acted directly on by
the apply lever. This is referred to as a double-wrap
band design (the drum is completely encompassed/
wrapped by the band). The double-wrap band pro-
vides a greater holding power in comparison to the
single-wrap design.
OPERATION
KICKDOWN (FRONT) BAND
The kickdown band holds the common sun gear of
the planetary gear sets by applying and holding the
front clutch retainer, which is splined to the sun gear
driving shell, and in turn splined directly to the sun
gear. The application of the band by the servo is typ-
ically done by an apply lever and link bar.
LOW/REVERSE (REAR) BAND
The rear band holds the rear planet carrier sta-
tionary by being mounted around and applied to the
low/reverse drum.
Fig. 65 Accumulator in SECOND Gear Position
1 - BOTTOM OF BORE
2 - LINE PRESSURE
3 - SHUTTLE VALVE
Fig. 66 Accumulator Components
1 - INNER SPRING
2 - ACCUMULATOR PISTON
3 - OUTER SPRING
4 - SEAL RINGS
Fig. 67 Front Band
1 - FRONT BAND
2 - TRANSMISSION HOUSING
WJAUTOMATIC TRANSMISSION - 42RE 21 - 61
BANDS (Continued)

(8) Engine starts must be possible with shifter
lever in PARK or NEUTRAL gate positions only.
Engine starts must not be possible in any other gate
positions other than PARK or NEUTRAL.
(9) With shifter lever handle push-button not
depressed and lever detent in:
²PARK position- apply forward force on center of
handle and remove pressure. Engine start must be
possible.
²PARK position- apply rearward force on center
of handle and remove pressure. Engine start must be
possible.
²NEUTRAL position- engine start must be possi-
ble.
²NEUTRAL position, engine running and brakes
applied- Apply forward force on center of shift han-
dle. Transmission should not be able to shift into
REVERSE detent.
ELECTRONIC GOVERNOR
DESCRIPTION
Governor pressure is controlled electronically. Com-
ponents used for governor pressure control include:
²Governor body
²Valve body transfer plate
²Governor pressure solenoid valve
²Governor pressure sensor
²Fluid temperature thermistor
²Throttle position sensor (TPS)
²Transmission speed sensor
²Powertrain control module (PCM)
GOVERNOR PRESSURE SOLENOID VALVE
The solenoid valve is a duty-cycle solenoid which
regulates the governor pressure needed for upshifts
and downshifts. It is an electro-hydraulic device
located in the governor body on the valve body trans-
fer plate (Fig. 73).
GOVERNOR PRESSURE SENSOR
The governor pressure sensor measures output
pressure of the governor pressure solenoid valve (Fig.
74).
GOVERNOR BODY AND TRANSFER PLATE
The transfer plate is designed to supply transmis-
sion line pressure to the governor pressure solenoid
valve and to return governor pressure.
The governor pressure solenoid valve is mounted in
the governor body. The body is bolted to the lower
side of the transfer plate (Fig. 74).
GOVERNOR PRESSURE CURVES
There are four governor pressure curves pro-
grammed into the transmission control module. The
different curves allow the control module to adjust
governor pressure for varying conditions. One curve
is used for operation when fluid temperature is at, or
below, ±1ÉC (30ÉF). A second curve is used when fluid
temperature is at, or above, 10ÉC (50ÉF) during nor-
mal city or highway driving. A third curve is used
during wide-open throttle operation. The fourth curve
is used when driving with the transfer case in low
range.
OPERATION
Compensation is required for performance varia-
tions of two of the input devices. Though the slope of
the transfer functions is tightly controlled, offset may
vary due to various environmental factors or manu-
facturing tolerances.
The pressure transducer is affected by barometric
pressure as well as temperature. Calibration of the
zero pressure offset is required to compensate for
shifting output due to these factors.
Fig. 73 Governor Pressure Solenoid Valve
1 - SOLENOID FILTER
2 - GOVERNOR PRESSURE SOLENOID
Fig. 74 Governor Pressure Sensor
1 - GOVERNOR BODY
2 - GOVERNOR PRESSURE SENSOR/TRANSMISSION FLUID
TEMPERATURE THERMISTOR
WJAUTOMATIC TRANSMISSION - 42RE 21 - 65
BRAKE TRANSMISSION SHIFT INTERLOCK MECHANISM (Continued)

(3) Install new oil seal in housing using Seal
Installer C-3995-A (Fig. 84).
EXTENSION HOUSING SEAL
REMOVAL
(1) Raise vehicle.
(2) Mark propeller shaft and axle yoke for align-
ment reference.
(3) Disconnect and remove propeller shaft.
(4) Remove old seal with Seal Remover C-3985-B
(Fig. 85) from overdrive housing.
INSTALLATION
(1) Place seal in position on overdrive housing.
(2) Drive seal into overdrive housing with Seal
Installer C-3995-A (Fig. 86).
(3) Carefully guide propeller shaft slip yoke into
housing and onto output shaft splines. Align marks
made at removal and connect propeller shaft to rear
axle pinion yoke.
FLUID AND FILTER
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - EFFECTS OF
INCORRECT FLUID LEVEL
A low fluid level allows the pump to take in air
along with the fluid. Air in the fluid will cause fluid
pressures to be low and develop slower than normal.
If the transmission is overfilled, the gears churn the
fluid into foam. This aerates the fluid and causing
the same conditions occurring with a low level. In
either case, air bubbles cause fluid overheating, oxi-
dation and varnish buildup which interferes with
valve and clutch operation. Foaming also causes fluid
expansion which can result in fluid overflow from the
transmission vent or fill tube. Fluid overflow can eas-
ily be mistaken for a leak if inspection is not careful.
DIAGNOSIS AND TESTING - CAUSES OF
BURNT FLUID
Burnt, discolored fluid is a result of overheating
which has two primary causes.
Fig. 83 Bushing Removal - Typical
1 - REMOVER 6957
2 - EXTENSION HOUSING BUSHING
Fig. 84 Extension Housing Seal Installation
1 - SPECIAL TOOL C-3995-A OR C-3972-A
2 - SPECIAL TOOL C-4471
Fig. 85 Removing Overdrive Housing Yoke Seal
1 - SPECIAL TOOL C-3985-B
2 - SEAL
Fig. 86 Installing Overdrive Housing Seal
1 - SPECIAL TOOL C-3995-A OR C-3972-A
2 - SPECIAL TOOL C-4471
WJAUTOMATIC TRANSMISSION - 42RE 21 - 69
EXTENSION HOUSING BUSHING (Continued)

(1) A result of restricted fluid flow through the
main and/or auxiliary cooler. This condition is usu-
ally the result of a faulty or improperly installed
drainback valve, a damaged main cooler, or severe
restrictions in the coolers and lines caused by debris
or kinked lines.
(2) Heavy duty operation with a vehicle not prop-
erly equipped for this type of operation. Trailer tow-
ing or similar high load operation will overheat the
transmission fluid if the vehicle is improperly
equipped. Such vehicles should have an auxiliary
transmission fluid cooler, a heavy duty cooling sys-
tem, and the engine/axle ratio combination needed to
handle heavy loads.
DIAGNOSIS AND TESTING - FLUID
CONTAMINATION
Transmission fluid contamination is generally a
result of:
²adding incorrect fluid
²failure to clean dipstick and fill tube when
checking level
²engine coolant entering the fluid
²internal failure that generates debris
²overheat that generates sludge (fluid break-
down)
²failure to reverse flush cooler and lines after
repair
²failure to replace contaminated converter after
repair
The use of non-recommended fluids can result in
transmission failure. The usual results are erratic
shifts, slippage, abnormal wear and eventual failure
due to fluid breakdown and sludge formation. Avoid
this condition by using recommended fluids only.
The dipstick cap and fill tube should be wiped
clean before checking fluid level. Dirt, grease and
other foreign material on the cap and tube could fall
into the tube if not removed beforehand. Take the
time to wipe the cap and tube clean before withdraw-
ing the dipstick.
Engine coolant in the transmission fluid is gener-
ally caused by a cooler malfunction. The only remedy
is to replace the radiator as the cooler in the radiator
is not a serviceable part. If coolant has circulated
through the transmission, an overhaul is necessary.
The transmission cooler and lines should be
reverse flushed whenever a malfunction generates
sludge and/or debris. The torque converter should
also be replaced at the same time.
Failure to flush the cooler and lines will result in
recontamination. Flushing applies to auxiliary coolers
as well. The torque converter should also be replaced
whenever a failure generates sludge and debris. This
is necessary because normal converter flushing proce-
dures will not remove all contaminants.
STANDARD PROCEDURE
STANDARD PROCEDURE - FLUID LEVEL
CHECK
Low fluid level can cause a variety of conditions
because it allows the pump to take in air along with
the fluid. As in any hydraulic system, air bubbles
make the fluid spongy, therefore, pressures will be
low and build up slowly.
Improper filling can also raise the fluid level too
high. When the transmssion has too much fluid, the
geartrain churns up foam and cause the same condi-
tions which occur with a low fluid level.
In either case, air bubbles can cause overheating
and/or fluid oxidation, and varnishing. This can
interfere with normal valve, clutch, and accumulator
operation. Foaming can also result in fluid escaping
from the transmission vent where it may be mis-
taken for a leak.
After the fluid has been checked, seat the dipstick
fully to seal out water and dirt.
The transmission has a dipstick to check oil level.
It is located on the right side of the engine. Be sure
to wipe all dirt from dipstick handle before removing.
Fluid level is checked with the engine running at
curb idle speed, the transmission in NEUTRAL and
the transmission fluid at normal operating tempera-
ture.The engine should be running at idle
speed for at least one minute, with the vehicle
on level ground.
The transmission fluid level can be checked two
ways.
PROCEDURE ONE
(1) Transmission fluid must be at normal operat-
ing temperature for accurate fluid level check. Drive
vehicle if necessary to bring fluid temperature up to
normal hot operating temperature of 82ÉC (180ÉF).
(2) Position vehicle on level surface.
(3) Start and run engine at curb idle speed.
(4) Apply parking brakes.
(5) Shift transmission momentarily into all gear
ranges. Then shift transmission back to NEUTRAL.
(6) Clean top of filler tube and dipstick to keep
dirt from entering tube.
(7) Remove dipstick (Fig. 87) and check fluid level
as follows:
(a) Correct acceptable level is in crosshatch area.
(b) Correct maximum level is to MAX arrow
mark.
(c) Incorrect level is at or below MIN line.
(d) If fluid is low, add only enough MopartAT F
+4, type 9602, to restore correct level. Do not over-
fill.
21 - 70 AUTOMATIC TRANSMISSION - 42REWJ
FLUID AND FILTER (Continued)

FRONT CLUTCH
DESCRIPTION
The front clutch assembly (Fig. 91) is composed of
the front clutch retainer, pressure plate, clutch
plates, driving discs, piston, piston return spring,
return spring retainer, and snap-rings. The frontclutch is the forward-most component in the trans-
mission geartrain and is directly behind the oil pump
and is considered a driving component.
NOTE: The number of discs and plates may vary
with each engine and vehicle combination.
Fig. 91 Front Clutch Components
1 - SNAP-RING (WAVE) 7 - SEAL
2 - REACTION PLATE 8 - PISTON
3 - CLUTCH DISC 9 - SPRING
4 - CLUTCH PLATE 10 - SNAP-RING
5 - SEAL 11 - SPRING RETAINER
6 - CLUTCH RETAINER
WJAUTOMATIC TRANSMISSION - 42RE 21 - 73