2002 JEEP GRAND CHEROKEE 545RFE

PARK LOCK CABLE
REMOVAL
(1) Place the shifter in the PARK position.
(2) Lower the steering column cover.
(3) With the ignition switch in the ªRUNº position
depress the park lock cable locking tab, located on
top of the cable connector at the steering column and
pull the park lock cable straight out.
(4) Remove the park lock cable from steering col-
umn (Fig. 97).
(5) Remove the floor console and related trim.
(Refer to 23 - BODY/INTERIOR/FLOOR CONSOLE -
REMOVAL)
(6) Disconnect the park lock cable from the shift
BTSI lever and remove the cable from the shifter
assembly bracket.
(7) Release the park lock cable from any remaining
clips.
(8) Remove park lock cable from the vehicle.
INSTALLATION
NOTE: The gearshift cable must be secured into
position and properly adjusted before the installa-
tion of the Park Lock Cable.
(1) Verify that the shifter is in the PARK position.
(2) Push the park lock cable straight into the
square mounting hole in the steering column until
cable snaps in place.
(3) Route park lock cable to the shifter mecha-
nism.
(4) Install the park lock cable end fitting into
shifter BTSI lever.
(5) Pull rearward on the cable housing to snap
park lock cable adjuster ears into floor shifter
bracket.
(6) Place the ignition key cylinder in the ACCES-
SORY position.
(7) Push the cable adjuster lock clamp downward
to lock it.
(8) Test the park lock cable operation.
(9) Install the floor console and related trim.
(Refer to 23 - BODY/INTERIOR/FLOOR CONSOLE -
INSTALLATION)
Fig. 97 Brake Transmission Shift Interlock
1 - SHIFT MECHANISM 4 - STEERING COLUMN ASSEMBLY
2 - SHIFTER BTSI LEVER 5 - INTERLOCK CABLE
3 - ADJUSTMENT CLIP
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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. 98) 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: 100
lbs. 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. 99) 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 pres-
sure. 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. 98 Force and Pressure Relationship
Fig. 99 Pressure on a Confined Fluid
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FORCE MULTIPLICATION
Using the 10 PSI example used in the illustration
(Fig. 100), a force of 1000 lbs. can be moved with a
force of only 100 lbs. The secret of force multiplica-
tion in hydraulic systems is the total fluid contact
area employed. The illustration, (Fig. 100), shows an
area that is ten times larger than the original area.
The pressure created with the smaller 100 lb. input
is 10 PSI. The concept ªpressure is the same every-
whereº means that the pressure underneath the
larger piston is also 10 PSI. Pressure is equal to the
force applied divided by the contact area. Therefore,
by means of simple algebra, the output force may be
found. This concept is extremely important, as it is
also used in the design and operation of all shift
valves and limiting valves in the valve body, as well
as the pistons, of the transmission, which activate
the clutches and bands. It is nothing more than
using a difference of area to create a difference in
pressure to move an object.
PISTON TRAVEL
The relationship between hydraulic lever and a
mechanical lever is the same. With a mechanical
lever it's a weight-to-distance output rather than a
pressure-to-area output. Using the same forces and
areas as in the previous example, the smaller piston
(Fig. 101) has to move ten times the distance
required to move the larger piston one inch. There-
fore, for every inch the larger piston moves, the
smaller piston moves ten inches. This principle is
true in other instances also. A common garage floor
jack is a good example. To raise a car weighing 2000
lbs., an effort of only 100 lbs. may be required. For
every inch the car moves upward, the input piston at
the jack handle must move 20 inches downward.
Fig. 100 Force Multiplication
Fig. 101 Piston Travel
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PISTONS (Continued)

PLANETARY GEARTRAIN
DESCRIPTION
The planetary geartrain is located behind the 4C
retainer/bulkhead, toward the rear of the transmis-
sion. The planetary geartrain consists of three pri-
mary assemblies:
²Reaction (Fig. 102).
²Reverse (Fig. 103).
²Input (Fig. 103).
Fig. 102 Reaction Planetary Geartrain
1 - BEARING NUMBER 8 5 - BEARING NUMBER 7
2 - BEARING NUMBER 9 6 - THRUST PLATE (SELECT)
3 - REACTION PLANETARY CARRIER 7 - BEARING NUMBER 6
4 - REACTION SUN GEAR 8 - REACTION ANNULUS
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Fig. 103 Reverse/Input Planetary Geartrain
1 - SNAP-RING 5 - INPUT PLANETARY CARRIER
2 - BEARING NUMBER 10 6 - INPUT SUN GEAR
3 - BEARING NUMBER 11 7 - REVERSE PLANETARY CARRIER
4 - INPUT ANNULUS
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PLANETARY GEARTRAIN (Continued)

OPERATION
REACTION PLANETARY GEARTRAIN
The reaction planetary carrier and reverse sun
gear of the reaction planetary geartrain are a single
component which is held by the 2C clutch when
required. The reaction annulus gear is a stand alone
component that can be driven by the reverse clutch
or held by the 4C clutch. The reaction sun gear is
driven by the overdrive clutch.
REVERSE PLANETARY GEARTRAIN
The reverse planetary geartrain is the middle of
the three planetary sets. The reverse planetary car-
rier can be driven by the overdrive clutch as
required. The reverse planetary carrier is also
splined to the input annulus gear, which can be held
by the low/reverse clutch. The reverse planetary
annulus, input planetary carrier, and output shaft
are all one piece.
INPUT PLANETARY GEARTRAIN
The input sun gear of the input planetary
geartrain is driven by the underdrive clutch.
DISASSEMBLY
(1) Remove the snap-ring holding the input annu-
lus into the input carrier (Fig. 104).
(2) Remove the input annulus from the input car-
rier (Fig. 104).
(3) Remove the number 9 bearing from the reverse
planetary carrier. Note that this planetary carrier
has four pinion gears.
(4) Remove the reverse planetary gear carrier (Fig.
104).
(5) Remove the number 10 bearing from the input
sun gear (Fig. 104).
(6) Remove the input sun gear from the input car-
rier (Fig. 104).
(7) Remove the number 11 bearing from the input
carrier (Fig. 104).
CLEANING
Clean the planetary components in solvent and dry
them with compressed air.
INSPECTION
Check sun gear and driving shell condition.
Replace the gear if damaged or if the bushings are
scored or worn. The bushings are not serviceable.
Fig. 104 Reverse/Input Planetary Carrier Assembly
1 - SNAP-RING 5 - INPUT PLANETARY CARRIER
2 - BEARING NUMBER 10 6 - INPUT SUN GEAR
3 - BEARING NUMBER 11 7 - REVERSE PLANETARY CARRIER
4 - INPUT ANNULUS
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PLANETARY GEARTRAIN (Continued)

Replace the driving shell if worn, cracked or dam-
aged.
Replace planetary gear sets if gears, pinion pins, or
carrier are damaged in any way. Replace the annulus
gears and supports if either component is worn or
damaged.
Replace the output shaft if the machined surfaces
are scored, pitted, or damaged in any way. Also
replace the shaft if the splines are damaged, or
exhibits cracks at any location.
ASSEMBLY
(1) Clean and inspect all components. Replace any
components which show evidence of excessive wear
or scoring.
(2) Install the number 11 bearing into the input
planetary carrier so that the inner race will be
toward the front of the transmission (Fig. 104).
(3) Install the input sun gear into the input carrier
(Fig. 104).
(4) Install the number 10 bearing onto the rear of
the reverse planetary carrier with the inner race
toward the carrier (Fig. 104).
(5) Install the number 9 bearing onto the front of
the reverse planetary carrier with the outer race
toward the carrier and the inner race facing upward
(Fig. 104).
(6) Install the reverse planetary gear carrier into
the input carrier (Fig. 104).
(7) Install the input annulus gear into the input
carrier (Fig. 104).
(8) Install the snap-ring to hold the input annulus
gear into the input carrier (Fig. 104).
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.
MANUAL SECOND (2) range provides FIRST and
SECOND gear only.
DRIVE range provides FIRST, SECOND, THIRD
and OVERDRIVE FOURTH and FIFTH gear ranges.
The shift into OVERDRIVE FOURTH and FIFTH
gear range occurs only after the transmission hascompleted the shift into D THIRD gear range. No
further movement of the shift mechanism is required
to complete the 3-4 or 4-5 shifts.
The FOURTH and FIFTH gear upshifts occurs
automatically when the overdrive selector switch is
in the ON position. An upshift to FOURTH and
FIFTH gears may not occur or may be delayed in
some of the possible shift schedules. (Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/TRANSMISSION CONTROL MODULE -
OPERATION)
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. 105).
(4) Disconnect the park lock cable from the shifter
BTSI lever and the shifter assembly bracket. (Fig.
106)
(5) Disconnect the transfer case shift cable from
the transfer case shift lever pin (Fig. 107), 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.
(8) Disengage all wiring connectors from the
shifter assembly.
(9) Remove all nuts holding the shifter assembly to
the floor pan (Fig. 108).
Fig. 105 Transmission Shift Cable
1 - SHIFT LEVER PIN
2 - ADJUSTMENT SCREW
3 - SHIFT CABLE
4 - SHIFTER ASSEMBLY BRACKET
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PLANETARY GEARTRAIN (Continued)

(10) Remove the shifter assembly from the vehicle.
Fig. 106 Brake Transmission Interlock Cable
1 - SHIFT MECHANISM 4 - STEERING COLUMN ASSEMBLY
2 - SHIFTER BTSI LEVER 5 - INTERLOCK CABLE
3 - ADJUSTMENT CLIP
Fig. 107 Transfer Case Shift Cable
1 - CLIP
2 - SHIFTER
3 - TRANSFER CASE SHIFT LEVER PIN
4 - TRANSFER CASE SHIFT CABLE
Fig. 108 Shifter Assembly
1 - FLOOR PAN
2 - SHIFTER ASSEMBLY
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SHIFT MECHANISM (Continued)