reverse JEEP GRAND CHEROKEE 2002 WJ / 2.G Service Manual

PROCEDURE TWO
(1) Start engine and apply parking brake.
(2) Shift the transmission into DRIVE for approxi-
mately 2 seconds.
(3) Shift the transmission into REVERSE for
approximately 2 seconds.
(4) Shift the transmission into PARK.
(5) Hook up DRBtscan tool and select engine.
(6) Select sensors.
(7) Read the transmission temperature value.
(8) Compare the fluid temperature value with the
figure. (Fig. 88)
(9) Adjust transmission fluid level shown on the
dipstick according to the figure.NOTE: After adding any fluid to the transmission,
wait a minimum of 2 minutes for the oil to fully
drain from the fill tube into the transmission before
rechecking the fluid level.
(10) Check transmission for leaks.
STANDARD PROCEDURE - FLUID AND FILTER
REPLACEMENT
For proper service intervals (Refer to LUBRICA-
TION & MAINTENANCE/MAINTENANCE SCHED-
ULES - DESCRIPTION). The service fluid fill after a
filter change is approximately 3.8 liters (4.0 quarts).
REMOVAL
(1) Hoist and support vehicle on safety stands.
(2) Place a large diameter shallow drain pan
beneath the transmission pan.
(3) Remove bolts holding front and sides of pan to
transmission (Fig. 89).
(4) Loosen bolts holding rear of pan to transmis-
sion.
(5) Slowly separate front of pan and gasket away
from transmission allowing the fluid to drain into
drain pan.
(6) Hold up pan and remove remaining bolt hold-
ing pan to transmission.
Fig. 88 42/44RE Fluid Fill Graph
Fig. 87 Dipstick Fluid Level Marks - Typical
1 - DIPSTICK
2 - MAXIMUM CORRECT FLUID LEVEL
3 - ACCEPTABLE FLUID LEVEL
WJAUTOMATIC TRANSMISSION - 42RE 21 - 71
FLUID AND FILTER (Continued)

GEARSHIFT CABLE
DIAGNOSIS AND TESTING - GEARSHIFT
CABLE
(1) The floor shifter lever and gate positions
should be in alignment with all transmission PARK,
NEUTRAL, and gear detent positions.
(2) Engine starts must be possible with floor shift
lever in PARK or NEUTRAL gate positions only.
Engine starts must not be possible in any other gear
position.
(3) With floor shift lever handle push-button not
depressed and lever in:
(a) PARK position - Apply forward force on cen-
ter of handle and remove pressure. Engine starts
must be possible.
(b) PARK position - Apply rearward force on cen-
ter of handle and remove pressure. Engine starts
must be possible.
(c) NEUTRAL position - Normal position. Engine
starts must be possible.
(d) NEUTRAL position - Engine running and
brakes applied, apply forward force on center of
shift handle. Transmission shall not be able to shift
from NEUTRAL to REVERSE.
REMOVAL
(1) Shift transmission into PARK.
(2) Raise vehicle.
Fig. 100 Front Servo Piston
1 - PISTON RINGS
2 - O-RING
3 - SNAP-RING
4 - SEAL RING
5 - PISTON ROD GUIDE
6 - SNAP-RING
7 - SERVO SPRING
8 - PISTON ROD
9 - SERVO PISTON
Fig. 101 Front Servo Piston
1 - PISTON RINGS
2 - O-RING
3 - SNAP-RING
4 - SEAL RING
5 - PISTON ROD GUIDE
6 - SNAP-RING
7 - SERVO SPRING
8 - PISTON ROD
9 - SERVO PISTON
Fig. 102 Front Servo
1 - PISTON RINGS
2 - O-RING
3 - SNAP-RING
4 - SEAL RING
5 - PISTON ROD GUIDE
6 - SNAP-RING
7 - SERVO SPRING
8 - PISTON ROD
9 - SERVO PISTON
21 - 78 AUTOMATIC TRANSMISSION - 42REWJ
FRONT SERVO (Continued)

CAUTION: The pump inner gear is a one way fit.
The bore on one side of the gear inside diameter
(I.D.) is chamfered. Be sure the chamfered side
faces forward (to front of pump).
(6) Install new thrust washer on hub of reaction
shaft support. Lubricate washer with transmission
fluid or petroleum jelly.
(7) If reaction shaft seal rings are being replaced,
install new seal rings on support hub (Fig. 120).
Lubricate seal rings with transmission fluid or petro-
leum jelly after installation. Squeeze each ring until
ring ends are securely hooked together.
CAUTION: The reaction shaft support seal rings will
break if overspread, or twisted. If new rings are
being installed, spread them only enough for instal-
lation. Also be very sure the ring ends are securely
hooked together after installation. Otherwise, therings will either prevent pump installation, or break
during installation.
(8) Install reaction shaft support on pump housing
(Fig. 121).
(9) Align reaction support on pump housing. Use
alignment marks made at disassembly. Or, rotate
support until bolt holes in support and pump housing
are all aligned (holes are offset for one-way fit).
(10) Install all bolts that attach support to pump
housing. Then tighten bolts finger tight.
(11) Tighten support-to-pump bolts to required
torque as follows:
(a) Reverse pump assembly and install it in
transmission case. Position pump so bolts are fac-
ing out and are accessible.
(b) Secure pump assembly in case with 2 or 3
bolts, or with pilot studs.
(c) Tighten support-to-pump bolts to 20 N´m (15
ft. lbs.).
(d) Remove pump assembly from transmission
case.
Fig. 118 Supporting Pump And Installing Outer Gear
1 - OUTER GEAR
2 - PUMP HOUSING
3 - WOOD BLOCKS
Fig. 119 Pump Inner Gear Installation
1 - OUTER GEAR
2 - INNER GEAR
Fig. 120 Hub Seal Ring Position
1 - SEAL RINGS
2 - SUPPORT HUB
Fig. 121 Assembling Reaction Shaft Support And
Pump Housing
1 - PUMP HOUSING
2 - REACTION SHAFT SUPPORT
21 - 84 AUTOMATIC TRANSMISSION - 42REWJ
OIL PUMP (Continued)

between the rollers and cam. This increased clear-
ance between the rollers and cam results in a free-
wheeling condition. When the inner race attempts to
rotate counterclockwise, the action causes the rollers
to roll in the same direction as the race, aided by the
pushing of the springs. As the rollers try to move in
the same direction as the inner race, they are
wedged between the inner and outer races due to the
design of the cam. In this condition, the clutch is
locked and acts as one unit.
DISASSEMBLY
NOTE: To service the overrunning clutch cam and
the overdrive piston retainer, the transmission
geartrain and the overdrive unit must be removed
from the transmission.
(1) Remove the overdrive piston (Fig. 190).
(2) Remove the overdrive piston retainer bolts.
(3) Remove overdrive piston retainer.
(4) Remove case gasket.
(5) Mark the position of the overrunning clutch
cam in the case (Fig. 191).
(6) Remove the overrunning clutch cam bolts.
(7) Remove the overrunning clutch cam.
CLEANING
Clean the overrunning clutch assembly, clutch cam,
low-reverse drum, and overdrive piston retainer in
solvent. Dry them with compressed air after clean-
ing.
INSPECTION
Inspect condition of each clutch part after cleaning.
Replace the overrunning clutch roller and spring
assembly if any rollers or springs are worn or dam-
aged, or if the roller cage is distorted, or damaged.
Replace the cam if worn, cracked or damaged.
Replace the low-reverse drum if the clutch race,
roller surface or inside diameter is scored, worn or
damaged.Do not remove the clutch race from
the low-reverse drum under any circumstances.
Replace the drum and race as an assembly if
either component is damaged.
Examine the overdrive piston retainer carefully for
wear, cracks, scoring or other damage. Be sure the
retainer hub is a snug fit in the case and drum.
Replace the retainer if worn or damaged.
ASSEMBLY
(1) Examine bolt holes in overrunning clutch cam.
Note that one hole isnot threaded(Fig. 192). This
hole must align with blank area in clutch cam bolt
circle (Fig. 193). Mark hole location on clutch cam
and blank area in case with grease pencil, paint
stripe, or scribe mark for assembly reference.
(2) Mark location of non-threaded hole in clutch
cam and blank area in bolt circle with grease pencil.
(3) Align and install overrunning clutch and cam
in case (Fig. 194). Be sure cam is correctly installed.
Bolt holes in cam are slightly countersunk on one
side. Be sure this side of cam faces rearward (toward
piston retainer).
(4) Verify that non-threaded hole in clutch cam is
properly aligned. Check alignment by threading a
bolt into each bolt hole. Adjust clutch cam position if
necessary.
Fig. 190 Overdrive Piston Removal
1 - OVERDRIVE CLUTCH PISTON
2 - INTERMEDIATE SHAFT
3 - SELECTIVE SPACER
4 - PISTON RETAINER
Fig. 191 Overrunning Clutch Cam Removal
1 - ALIGN MARKS IDENTIFYING NON-THREADED HOLE IN
CAM AND CASE
2 - OVERRUNNING CLUTCH ASSEMBLY
21 - 106 AUTOMATIC TRANSMISSION - 42REWJ
OVERRUNNING CLUTCH CAM/OVERDRIVE PISTON RETAINER (Continued)

PARK/NEUTRAL POSITION
SWITCH
DIAGNOSIS AND TESTING - PARK/NEUTRAL
POSITION SWITCH
The center terminal of the park/neutral position
switch is the starter-circuit terminal. It provides the
ground for the starter solenoid circuit through the
selector lever in PARK and NEUTRAL positions only.
The outer terminals on the switch are for the backup
lamp circuit.
SWITCH TEST
To test the switch, remove the wiring connector.
Test for continuity between the center terminal and
the transmission case. Continuity should exist only
when the transmission is in PARK or NEUTRAL.Shift the transmission into REVERSE and test
continuity at the switch outer terminals. Continuity
should exist only when the transmission is in
REVERSE. Continuity should not exist between the
outer terminals and the case.
Check gearshift linkage adjustment before replac-
ing a switch that tests faulty.
REMOVAL
(1) Raise vehicle and position drain pan under
switch.
(2) Disconnect switch wires.
(3) Remove switch from case.
INSTALLATION
(1) Move shift lever to PARK and NEUTRAL posi-
tions. Verify that switch operating lever fingers are
centered in switch opening in case (Fig. 198).
Fig. 197 Brake Transmission Shift Interlock
1 - SHIFT MECHANISM 4 - STEERING COLUMN ASSEMBLY
2 - SHIFTER BTSI LEVER 5 - INTERLOCK CABLE
3 - ADJUSTMENT CLIP
WJAUTOMATIC TRANSMISSION - 42RE 21 - 109
PARK LOCK CABLE (Continued)

(2) Install new seal on switch and install switch in
case. Tighten switch to 34 N´m (25 ft. lbs.) torque.
(3) Test continuity of new switch with 12V test
lamp.
(4) Connect switch wires and lower vehicle.
(5) Top off transmission fluid level.
PISTONS
DESCRIPTION
There are several sizes and types of pistons used in
an automatic transmission. Some pistons are used to
apply clutches. They all have in common the fact
that they are round or circular in shape, located
within a smooth walled cylinder, which is closed at
one end and converts fluid pressure into mechanical
movement. The fluid pressure exerted on the piston
is contained within the system through the use of
piston rings or seals.
OPERATION
The principal which makes this operation possible
is known as Pascal's Law. Pascal's Law can be stated
as: ªPressure on a confined fluid is transmitted
equally in all directions and acts with equal force on
equal areas.º
PRESSURE
Pressure (Fig. 199) is nothing more than force
(lbs.) divided by area (in or ft.), or force per unit
area. Given a 100 lb. block and an area of 100 sq. in.
on the floor, the pressure exerted by the block is: 100lbs. 100 in or 1 pound per square inch, or PSI as it is
commonly referred to.
PRESSURE ON A CONFINED FLUID
Pressure is exerted on a confined fluid (Fig. 200)
by applying a force to some given area in contact
with the fluid. A good example of this is a cylinder
filled with fluid and equipped with a piston that is
closely fitted to the cylinder wall. If a force is applied
to the piston, pressure will be developed in the fluid.
Of course, no pressure will be created if the fluid is
not confined. It will simply ªleakº past the piston.
There must be a resistance to flow in order to create
pressure. Piston sealing is extremely important in
hydraulic operation. Several kinds of seals are used
to accomplish this within a transmission. These
include but are not limited to O-rings, D-rings, lip
seals, sealing rings, or extremely close tolerances
between the piston and the cylinder wall. The force
exerted is downward (gravity), however, the principle
remains the same no matter which direction is taken.
The pressure created in the fluid is equal to the force
applied, divided by the piston area. If the force is 100
lbs., and the piston area is 10 sq. in., then the pres-
sure created equals 10 PSI. Another interpretation of
Pascal's Law is that regardless of container shape or
size, the pressure will be maintained throughout, as
long as the fluid is confined. In other words, the
pressure in the fluid is the same everywhere within
the container.
Fig. 198 Park/Neutral Position Switch
1 - NEUTRAL CONTACT
2 - MANUAL LEVER AND SWITCH PLUNGER IN REVERSE
POSITION
3 - PARK CONTACT
4 - SWITCH
Fig. 199 Force and Pressure Relationship
21 - 110 AUTOMATIC TRANSMISSION - 42REWJ
PARK/NEUTRAL POSITION SWITCH (Continued)

The selective snap-ring thicknesses are:
²0.107-0.109 in.
²0.098-0.100 in.
²0.095-0.097 in.
²0.083-0.085 in.
²0.076-0.078 in.
²0.071-0.073 in.
²0.060-0.062 in.
(16) Coat rear clutch thrust washer with petro-
leum jelly and install washer over input shaft and
into clutch retainer (Fig. 232). Use enough petroleum
jelly to hold washer in place.REAR SERVO
DESCRIPTION
The rear (low/reverse) servo consists of a single
stage or diameter piston and a spring loaded plug.
The spring is used to cushion the application of the
rear (low/reverse) band.
OPERATION
While in the de-energized state (no pressure
applied), the piston is held up in its bore by the pis-
ton spring. The plug is held down in its bore, in the
piston, by the plug spring. When pressure is applied
to the top of the piston, the plug is forced down in its
bore, taking up any clearance. As the piston moves, it
causes the plug spring to compress, and the piston
moves down over the plug. The piston continues to
move down until it hits the shoulder of the plug and
fully applies the band. The period of time from the
initial application, until the piston is against the
shoulder of the plug, represents a reduced shocking
of the band that cushions the shift.
DISASSEMBLY
(1) Remove small snap-ring and remove plug and
spring from servo piston (Fig. 233).
(2) Remove and discard servo piston seal ring.
CLEANING
Remove and discard the servo piston seal ring (Fig.
234). Then clean the servo components with solvent
and dry with compressed air. Replace either spring if
collapsed, distorted or broken. Replace the plug and
piston if cracked, bent, or worn. Discard the servo
snap-rings and use new ones at assembly.
Fig. 231 Checking Rear Clutch Pack Clearance
1 - DIAL INDICATOR
2 - PRESSURE PLATE
3 - SNAP-RING
4-STAND
5 - REAR CLUTCH
6 - GAUGE BAR
Fig. 232 Installing Rear Clutch Thrust Washer
1 - REAR CLUTCH RETAINER
2 - REAR CLUTCH THRUST WASHER
Fig. 233 Rear Servo Components
1 - SNAP-RING
2 - PISTON SEAL
3 - PISTON PLUG
4 - SPRING RETAINER
5 - SNAP-RING
6 - PISTON SPRING
7 - CUSHION SPRING
8 - PISTON
21 - 122 AUTOMATIC TRANSMISSION - 42REWJ
REAR CLUTCH (Continued)

ASSEMBLY
(1) Lubricate piston and guide seals (Fig. 235)
with petroleum jelly. Lubricate other servo parts with
MopartATF +4, type 9602, transmission fluid.
(2) Install new seal ring on servo piston.
(3) Assemble piston, plug, spring and new snap-
ring.
(4) Lubricate piston seal lip with petroleum jelly.
SHIFT MECHANISM
DESCRIPTION
The gear shift mechanism provides six shift posi-
tions which are:
²PARK (P)
²REVERSE (R)
²NEUTRAL (N)
²DRIVE (D)
²Manual SECOND (2)
²Manual LOW (1)
OPERATION
Manual LOW (1) range provides first gear only.
Overrun braking is also provided in this range. Man-
ual SECOND (2) range provides first and second gear
only.
DRIVE range provides first, second third and over-
drive fourth gear ranges. The shift into overdrive
fourth gear range occurs only after the transmission
has completed the shift into D third gear range. No
further movement of the shift mechanism is required
to complete the 3-4 shift.
The fourth gear upshift occurs automatically when
the overdrive selector switch is in the ON position.
No upshift to fourth gear will occur if any of the fol-
lowing are true:
²The transmission fluid temperature is below 10É
C (50É F) or above 121É C (250É F).
²The shift to third is not yet complete.
²Vehicle speed is too low for the 3-4 shift to occur.
²Battery temperature is below -5É C (23É F).
REMOVAL
(1) Remove any necessary console parts for access
to shift lever assembly and shifter cables. (Refer to
23 - BODY/INTERIOR/FLOOR CONSOLE -
REMOVAL)
(2) Shift transmission into PARK.
(3) Disconnect the transmission shift cable at shift
lever and shifter assembly bracket (Fig. 236).
(4) Disconnect the park lock cable from the shifter
BTSI lever and the shifter assembly bracket. (Fig.
237)
(5) Disconnect the transfer case shift cable from
the transfer case shift lever pin (Fig. 238), if
equipped.
(6) Remove the clip holding the transfer case shift
cable to the shifter assembly bracket, if equipped.
(7) Remove the transfer case shift cable from the
shifter assembly bracket, if equipped.
Fig. 234 Rear Servo Components
1 - SNAP-RING
2 - PISTON SEAL
3 - PISTON PLUG
4 - SPRING RETAINER
5 - SNAP-RING
6 - PISTON SPRING
7 - CUSHION SPRING
8 - PISTON
Fig. 235 Rear Servo Components
1 - SNAP-RING
2 - PISTON SEAL
3 - PISTON PLUG
4 - SPRING RETAINER
5 - SNAP-RING
6 - PISTON SPRING
7 - CUSHION SPRING
8 - PISTON
WJAUTOMATIC TRANSMISSION - 42RE 21 - 123
REAR SERVO (Continued)

TORQUE CONVERTER
DRAINBACK VALVE
DESCRIPTION
The drainback valve is located in the transmission
cooler outlet (pressure) line.
OPERATION
The valve prevents fluid from draining from the
converter into the cooler and lines when the vehicle
is shut down for lengthy periods. Production valves
have a hose nipple at one end, while the opposite end
is threaded for a flare fitting. All valves have an
arrow (or similar mark) to indicate direction of flow
through the valve.
STANDARD PROCEDURE - TORQUE
CONVERTER DRAINBACK VALVE
The converter drainback check valve is located in
the cooler outlet (pressure) line near the radiator
tank. The valve prevents fluid drainback when the
vehicle is parked for lengthy periods. The valve check
ball is spring loaded and has an opening pressure of
approximately 2 psi.
The valve is serviced as an assembly; it is not
repairable. Do not clean the valve if restricted, or
contaminated by sludge, or debris. If the valve fails,
or if a transmission malfunction occurs that gener-
ates significant amounts of sludge and/or clutch par-
ticles and metal shavings, the valve must be
replaced.
The valve must be removed whenever the cooler
and lines are reverse flushed. The valve can be flow
tested when necessary. The procedure is exactly the
same as for flow testing a cooler.
If the valve is restricted, installed backwards, or in
the wrong line, it will cause an overheating condition
and possible transmission failure.
CAUTION: The drainback valve is a one-way flow
device. It must be properly oriented in terms of flow
direction for the cooler to function properly. The
valve must be installed in the pressure line. Other-
wise flow will be blocked and would cause an over-
heating condition and eventual transmission failure.
TRANSMISSION
TEMPERATURE SENSOR
DESCRIPTION
Transmission fluid temperature readings are sup-
plied to the transmission control module by the ther-
mistor (Fig. 254). The temperature readings are used
to control engagement of the fourth gear overdrive
clutch, the converter clutch, and governor pressure.
Normal resistance value for the thermistor at room
temperature is approximately 2000 ohms.
The thermistor is part of the governor pressure
sensor assembly and is immersed in transmission
fluid at all times.
OPERATION
The PCM prevents engagement of the converter
clutch and overdrive clutch, when fluid temperature
is below approximately 10ÉC (50ÉF).
If fluid temperature exceeds 126ÉC (260ÉF), the
PCM causes a 4-3 downshift and engage the con-
verter clutch. Engagement is according to the third
gear converter clutch engagement schedule.
The overdrive OFF lamp in the instrument panel
illuminates when the shift back to third occurs. The
transmission will not allow fourth gear operation
until fluid temperature decreases to approximately
110ÉC (230ÉF).
Fig. 254 Governor Pressure Sensor
1 - GOVERNOR BODY
2 - GOVERNOR PRESSURE SENSOR/TRANSMISSION FLUID
TEMPERATURE THERMISTOR
21 - 134 AUTOMATIC TRANSMISSION - 42REWJ

OPERATION
NOTE: Refer to the Hydraulic Schematics for a
visual aid in determining valve location, operation
and design.
CHECK BALLS
CHECK BALL NUMBER DESCRIPTION
1 Allows either the manual valve to put line pressure on the 1-2 governor plug or
the KD Valve to put WOT line pressure on the 1-2 governor plug.
2 Allows either the manual valve to put line pressure on the 2-3 governor plug or
the KD Valve to put WOT line pressure on the 2-3 governor plug.
3 Allows either the Reverse circuit or the 3rd gear circuit to pressurize the front
clutch.
4 Allows either the Manual Low circuit from the Manual Valve or the Reverse
from the Manual Valve circuit to pressurize the rear servo.
5 Directs line pressure to the spring end of the 2-3 shift valve in either Manual
Low or Manual 2nd, forcing the downshift to 2nd gear regardless of governor
pressure.
6 Provides a by-pass around the front servo orifice so that the servo can release
quickly.
7 Provides a by-pass around the rear clutch orifice so that the clutch can release
quickly.
8 Directs reverse line pressure through an orifice to the throttle valve eliminating
the extra leakage and insuring that Reverse line pressure pressure will be
sufficient.
9 Provides a by-pass around the rear servo orifice so that the servo can release
quickly.
ECE (10) Allows the lockup clutch to used at WOT in 3rd gear by putting line pressure
from the 3-4 Timing Valve on the interlock area of the 2-3 shift valve, thereby
preventing a 3rd gear Lock-up to 2nd gear kickdown.
WJAUTOMATIC TRANSMISSION - 42RE 21 - 139
VALVE BODY (Continued)