key JEEP GRAND CHEROKEE 2003 WJ / 2.G Owners Manual

INSTALLATION
INSTALLATION - 4.0L
The IAC motor is located on the throttle body.
(1) Install IAC motor to throttle body.
(2) Install and tighten two mounting bolts (screws)
to 7 N´m (60 in. lbs.) torque.
(3) Install electrical connector.
(4) Install air cleaner duct/air box to throttle body.
INSTALLATION - 4.7L
(1) Install IAC motor to throttle body.
(2) Install and tighten two mounting bolts (screws)
to 7 N´m (60 in. lbs.) torque.
(3) Install electrical connector.
(4) Install air duct/air box to throttle body.
INTAKE AIR TEMPERATURE
SENSOR
DESCRIPTION
The 2±wire Intake Manifold Air Temperature (IAT)
sensor is installed in the intake manifold with the
sensor element extending into the air stream.
The IAT sensor is a two-wire Negative Thermal
Coefficient (NTC) sensor. Meaning, as intake mani-
fold temperature increases, resistance (voltage) in the
sensor decreases. As temperature decreases, resis-
tance (voltage) in the sensor increases.
OPERATION
The IAT sensor provides an input voltage to the
Powertrain Control Module (PCM) indicating the
density of the air entering the intake manifold based
upon intake manifold temperature. At key-on, a
5±volt power circuit is supplied to the sensor from
the PCM. The sensor is grounded at the PCM
through a low-noise, sensor-return circuit.
The PCM uses this input to calculate the following:
²Injector pulse-width
²Adjustment of spark timing (to help prevent
spark knock with high intake manifold air-charge
temperatures)
The resistance values of the IAT sensor is the same
as for the Engine Coolant Temperature (ECT) sensor.
REMOVAL
REMOVAL - 4.0L
The Intake Manifold Air Temperature (IAT) sensor
is installed into the intake manifold plenum near the
front of the throttle body (Fig. 27).
(1) Disconnect electrical connector from sensor.
(2) Remove sensor from intake manifold.
REMOVAL - 4.7L
The Intake Manifold Air Temperature (IAT) sensor
is located on the left side of the intake manifold.
Threaded Type Sensor
(1) Disconnect electrical connector from sensor.
(2) Remove sensor from intake manifold (Fig. 28).
Snap-In Type Sensor
(1) Disconnect electrical connector from IAT sen-
sor.
(2) Clean dirt from intake manifold at sensor base.
(3) Gently lift on small plastic release tab (Fig. 30)
or (Fig. 29) and rotate sensor about 1/4 turn counter-
clockwise for removal.
(4) Check condition of sensor o-ring.
Fig. 27 Intake Manifold Air Sensor LocationÐ4.0L
Engine
1 - MOUNTING BOLTS (4)
2 - THROTTLE BODY
3 - IAC MOTOR
4 - ELEC. CONN.
5 - TPS
6 - MAP SENSOR
7 - ELEC. CONN.
8 - IAT SENSOR
9 - ELEC. CONN.
14 - 46 FUEL INJECTIONWJ
IDLE AIR CONTROL MOTOR (Continued)

MAP SENSOR
DESCRIPTION
DESCRIPTION
On the 4.0L six-cylinder engine the MAP sensor is
mounted to the engine throttle body. On the 4.7L V-8
engine the MAP sensor is mounted to front of the
intake manifold.
DESCRIPTION - 4.7L
The MAP sensor is located on the front of the
intake manifold. An o-ring seals the sensor to the
intake manifold.
OPERATION
The MAP sensor is used as an input to the Power-
train Control Module (PCM). It contains a silicon
based sensing unit to provide data on the manifold
vacuum that draws the air/fuel mixture into the com-
bustion chamber. The PCM requires this information
to determine injector pulse width and spark advance.
When manifold absolute pressure (MAP) equals
Barometric pressure, the pulse width will be at max-
imum.
A 5 volt reference is supplied from the PCM and
returns a voltage signal to the PCM that reflects
manifold pressure. The zero pressure reading is 0.5V
and full scale is 4.5V. For a pressure swing of 0±15
psi, the voltage changes 4.0V. To operate the sensor,
it is supplied a regulated 4.8 to 5.1 volts. Ground is
provided through the low-noise, sensor return circuit
at the PCM.
The MAP sensor input is the number one contrib-
utor to fuel injector pulse width. The most important
function of the MAP sensor is to determine baromet-
ric pressure. The PCM needs to know if the vehicle is
at sea level or at a higher altitude, because the air
density changes with altitude. It will also help to cor-
rect for varying barometric pressure. Barometric
pressure and altitude have a direct inverse correla-
tion; as altitude goes up, barometric goes down. At
key-on, the PCM powers up and looks at MAP volt-
age, and based upon the voltage it sees, it knows the
current barometric pressure (relative to altitude).
Once the engine starts, the PCM looks at the voltage
again, continuously every 12 milliseconds, and com-
pares the current voltage to what it was at key-on.
The difference between current voltage and what it
was at key-on, is manifold vacuum.
During key-on (engine not running) the sensor
reads (updates) barometric pressure. A normal range
can be obtained by monitoring a known good sensor.
As the altitude increases, the air becomes thinner
(less oxygen). If a vehicle is started and driven to avery different altitude than where it was at key-on,
the barometric pressure needs to be updated. Any
time the PCM sees Wide Open Throttle (WOT), based
upon Throttle Position Sensor (TPS) angle and RPM,
it will update barometric pressure in the MAP mem-
ory cell. With periodic updates, the PCM can make
its calculations more effectively.
The PCM uses the MAP sensor input to aid in cal-
culating the following:
²Manifold pressure
²Barometric pressure
²Engine load
²Injector pulse-width
²Spark-advance programs
²Shift-point strategies (certain automatic trans-
missions only)
²Idle speed
²Decel fuel shutoff
The MAP sensor signal is provided from a single
piezoresistive element located in the center of a dia-
phragm. The element and diaphragm are both made
of silicone. As manifold pressure changes, the dia-
phragm moves causing the element to deflect, which
stresses the silicone. When silicone is exposed to
stress, its resistance changes. As manifold vacuum
increases, the MAP sensor input voltage decreases
proportionally. The sensor also contains electronics
that condition the signal and provide temperature
compensation.
The PCM recognizes a decrease in manifold pres-
sure by monitoring a decrease in voltage from the
reading stored in the barometric pressure memory
cell. The MAP sensor is a linear sensor; meaning as
pressure changes, voltage changes proportionately.
The range of voltage output from the sensor is usu-
ally between 4.6 volts at sea level to as low as 0.3
volts at 26 in. of Hg. Barometric pressure is the pres-
sure exerted by the atmosphere upon an object. At
sea level on a standard day, no storm, barometric
pressure is approximately 29.92 in Hg. For every 100
feet of altitude, barometric pressure drops .10 in. Hg.
If a storm goes through it can change barometric
pressure from what should be present for that alti-
tude. You should know what the average pressure
and corresponding barometric pressure is for your
area.
REMOVAL
REMOVAL - 4.0L
The MAP sensor is mounted to the side of the
throttle body (Fig. 40). An L-shaped rubber fitting is
used to connect the MAP sensor to throttle body (Fig.
31).
(1) Remove air cleaner duct and air resonator box
at throttle body.
14 - 48 FUEL INJECTIONWJ

COLUMN
TABLE OF CONTENTS
page page
COLUMN
DESCRIPTION
SERVICE WARNINGS AND CAUTIONS......7
REMOVAL.............................8
INSTALLATION.........................11
SPECIFICATIONS
TORQUE CHART......................12
SPECIAL TOOLS
STEERING COLUMN...................12
IGNITION SWITCH
DESCRIPTION.........................12
DIAGNOSIS AND TESTING - IGNITION
SWITCH............................12
REMOVAL
IGNITION SWITCH REMOVAL............13INSTALLATION
IGNITION SWITCH INSTALLATION........13
KEY-IN IGNITION SWITCH
DESCRIPTION.........................14
OPERATION...........................14
DIAGNOSIS AND TESTING
KEY-IN IGNITION SWITCH..............14
LOCK CYLINDER
REMOVAL.............................14
INSTALLATION.........................15
STEERING WHEEL
REMOVAL.............................15
INSTALLATION.........................15
COLUMN
DESCRIPTION
SERVICE WARNINGS AND CAUTIONS
DESCRIPTION
The tilt column (Fig. 1) has been designed to be
serviced as an assembly, less the wiring, switches,
shrouds, steering wheel, etc. Most steering column
components can be serviced without removing the
steering column from the vehicle.To service the steering wheel, switches or air-
bag,(Refer to 8 - ELECTRICAL/RESTRAINTS -
WARNING).
WARNING: THE AIRBAG SYSTEM IS A SENSITIVE,
COMPLEX ELECTRO-MECHANICAL UNIT. BEFORE
ATTEMPTING TO DIAGNOSE, REMOVE OR INSTALL
THE AIRBAG SYSTEM COMPONENTS YOU MUST
FIRST DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE. THEN WAIT TWO
MINUTES FOR THE SYSTEM CAPACITOR TO DIS-
CHARGE. FAILURE TO DO SO COULD RESULT IN
ACCIDENTAL DEPLOYMENT OF THE AIRBAG AND
POSSIBLE PERSONAL INJURY. THE FASTENERS,
SCREWS, AND BOLTS, ORIGINALLY USED FOR
THE AIRBAG COMPONENTS, HAVE SPECIAL COAT-
INGS AND ARE SPECIFICALLY DESIGNED FOR THE
AIRBAG SYSTEM. THEY MUST NEVER BE
REPLACED WITH ANY SUBSTITUTES. ANYTIME A
NEW FASTENER IS NEEDED, REPLACE WITH THE
CORRECT FASTENERS PROVIDED IN THE SERVICE
PACKAGE OR FASTENERS LISTED IN THE PARTS
BOOKS.
CAUTION: Safety goggles should be worn at all
times when working on steering columns.
Fig. 1 Steering Column
WJCOLUMN 19 - 7

(10) Disconnect the multifuction switch (Fig. 9)
and ignition switch harness.
(11) Remove the multifuction switch screw from
underneath the switch (Fig. 10). Slide the multifuc-
tion switch and clock spring off the column as an
assembly (Fig. 11).(12) Turn the ignition key to the on position then
release and remove the shifter interlock cable (Fig.
12) from the ignition lock cylinder housing.
Fig. 9 Multifuction Switch Harness
1 - MULTIFUNCTION SWITCH
2 - MULTIFUNCTION SWITCH HARNESS
Fig. 10 Multifuction
1 - CLOCK SPRING
2 - SCREW
3 - MULTI-FUNCTION SWITCH MOUNTING HOUSING
Fig. 11 Multifuction Switch And Clock Spring
1 - MULTI-FUNCTION SWITCH ASSEMBLY
2 - CLOCKSPRING
Fig. 12 Shifter Interlock Cable
1 - LOCK CYLINDER HOUSING
2 - INTERLOCK CABLE
19 - 10 COLUMNWJ
COLUMN (Continued)

(13) Remove the column coupler bolt (Fig. 13) and
slide the coupler off the column shaft.
(14) Remove the column mounting nuts (Fig. 13)
and lower column off mounting studs. Remove the
column from the vehicle.
(15) Remove the ignition switch, cylinder and
SKIM, (Refer to 19 - STEERING/COLUMN/LOCK
CYLINDER HOUSING - REMOVAL). (Fig. 14).INSTALLATION
WARNING: BEFORE SERVICING THE STEERING COL-
UMN THE AIRBAG SYSTEM MUST BE DISARMED.
FAILURE TO DO SO MAY RESULT IN ACCIDENTAL
DEPLOYMENT OF THE AIRBAG AND POSSIBLE PER-
SONAL INJURY. (Refer to 8 - ELECTRICAL/RE-
STRAINTS/DRIVER AIRBAG - INSTALLATION).
(1) Install the ignition switch, cylinder and SKIM-
,(Refer to 19 - STEERING/COLUMN/IGNITION
SWITCH - INSTALLATION).
(2) Install the column into the vehicle and lift the
column up onto the mounting studs. Install the
mounting nuts and tighten to 12 N´m (105 in. lbs.).
(3) Slid the coupler onto the column shaft and
install the coupler bolt. Tighten the coupler bolt to 49
N´m (36 ft. lbs.).
(4) Turn the ignition key to the on position then
release and install the shifter interlock cable (Fig.
12) into ignition lock cylinder housing.
(5) Verify ignition switch and shifter interlock
operation.,(Refer to 21 - TRANSMISSION/TRANS-
AXLE/AUTOMATIC - 42RE/GEAR SHIFT CABLE -
ADJUSTMENTS).
(6) Slide the multifuction switch and clock spring
onto the column as an assembly (Fig. 11).
(7) Install the multifuction switch mounting screw
(Fig. 10).
(8) Connect the multifuction switch (Fig. 9) and
ignition switch harness.
(9) Install the upper fixed shroud and mounting
screws (Fig. 8).
(10) Install the lower steering column shroud to
the steering column. Install and tighten the mount-
ing screw.
(11) Install the upper column shroud. Align the
upper shroud to the lower shroud and snap the two
shroud halves together.
(12) Install the knee blocker cover (Fig. 5),(Refer
to 23 - BODY/INSTRUMENT PANEL - INSTALLA-
TION).
(13) Install the cluster bezel by inserting it into
the instrument panel (Fig. 4).
(14) Align the steering wheel with the column
index spline and install the wheel on the column
shaft. Pull the clockspring wire harness through the
steering wheel armature spokes.
(15) Install and tighten the steering wheel mount-
ing nut to 61 N´m (45 ft. lbs.).
(16) Connect the steering wheel wire harness con-
nector to the clock spring connector.
(17) Install the airbag,(Refer to 8 - ELECTRICAL/
RESTRAINTS/DRIVER AIRBAG - INSTALLATION).
(18) Connect the negative (ground) cable to the
battery.
Fig. 13 Column Coupler Bolt And Mounting Nuts
1 - COLUMN MOUNTING NUTS
2 - COUPLER BOLT
Fig. 14 Ignition Switch And SKIM
1 - SKIM
2 - IGNITION SWITCH
WJCOLUMN 19 - 11
COLUMN (Continued)

SPECIFICATIONS
TORQUE CHART
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Steering Column
Steering Wheel Nut61 45 Ð
Steering Column
Column Bracket Nuts12 Ð 105
Steering Column
Shaft Coupler Bolts49 36 Ð
SPECIAL TOOLS
STEERING COLUMN
IGNITION SWITCH
DESCRIPTION
The electrical ignition switch is located on the
steering column. It is used as the main on/off switch-
ing device for most electrical components. The
mechanical key lock cylinder is used to engage/disen-
gage the electrical ignition switch.
DIAGNOSIS AND TESTING - IGNITION SWITCH
ELECTRICAL DIAGNOSIS
For ignition switch electrical schematics, refer to
Ignition Switch in Wiring Diagrams.
MECHANICAL DIAGNOSIS (KEY DIFFICULT TO
ROTATE)
Vehicles equipped with an automatic trans-
mission and a floor mounted shifter:a cable is
used to connect the interlock device in the steering
column assembly, to the transmission floor shift
lever. This interlock device is used to lock the trans-
mission shifter in the PARK position when the key
lock cylinder is rotated to the LOCKED or ACCES-
SORY position. The interlock device within the steer-
ing column is not serviceable. If repair is necessary,the steering column assembly must be replaced,(Re-
fer to 19 - STEERING/COLUMN - REMOVAL).
If the ignition key is difficult to rotate to or from
the LOCK or ACCESSORY position, it may not be
the fault of the key cylinder or the steering column
components. The brake transmission shift interlock
cable may be out of adjustment,(Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC -
44RE/SHIFT INTERLOCK MECHANISM - ADJUST-
MENTS) .
Vehicles equipped with an automatic trans-
mission and a steering column mounted shifter:
an interlock device is located within the steering col-
umn. This interlock device is used to lock the trans-
mission shifter in the PARK position when the key
lock cylinder is in the LOCKED or ACCESSORY
position. If it is difficult to rotate the key to or from
the LOCK or ACCESSORY position, the interlock
device within the steering column may be defective.
This device is not serviceable. If repair is necessary,
the steering column assembly must be replaced,(Re-
fer to 19 - STEERING/COLUMN - REMOVAL).
Vehicles equipped with a manual transmis-
sion and a floor mounted shifter:on certain mod-
els, a lever is located on the steering column behind
the ignition key lock cylinder. The lever must be
manually operated to allow rotation of the ignition
key lock cylinder to the LOCK or ACCESSORY posi-
tion. If it is difficult to rotate the key to the LOCK or
ACCESSORY position, the lever mechanism may be
defective. This mechanism is not serviceable. If
repair is necessary, the steering column assembly
must be replaced,(Refer to 19 - STEERING/COL-
UMN - REMOVAL).
On other models, the ignition key cylinder must be
depressed to allow it to be rotated into the LOCK or
ACCESSORY position. If it is difficult to rotate the
key to the LOCK or ACCESSORY position, the lock
mechanism within the steering column may be defec-
tive. This mechanism is not serviceable. If repair is
Puller C-3894-A
19 - 12 COLUMNWJ
COLUMN (Continued)

necessary, the steering column assembly must be
replaced,(Refer to 19 - STEERING/COLUMN -
REMOVAL).
REMOVAL
IGNITION SWITCH REMOVAL
The ignition key must be in the key cylinder for
cylinder removal. The key cylinder must be removed
first before removing ignition switch.
(1) Remove key cylinder. Refer to previous steps.
(2) Remove lower steering column cover screws
and remove cover (Fig. 19).
(3) Remove ignition switch mounting screw (Fig.
17). Use tamper proof torx bit to remove the screw.
(4) Using a small screwdriver, push on locking tab
(Fig. 15) and remove switch from steering column.
(5) Disconnect two electrical connectors at rear of
ignition switch (Fig. 17).
INSTALLATION
IGNITION SWITCH INSTALLATION
The ignition key must be in the key cylinder for
cylinder removal. The key cylinder must be removed
first before removing ignition switch.(1) Before installing ignition switch, rotate the slot
in the switch to the ON position (Fig. 16).
(2) Connect two electrical connectors to rear of
ignition switch. Make sure that locking tabs are fully
seated into wiring connectors.
(3) Position switch to column and install tamper
proof screw. Tighten screw to 3 N´m (26 in. lbs.).
(4) Install steering column lower cover.
Fig. 15 Ignition Switch Lock Tab
1 - LOCK TAB
2 - IGNITION SWITCH
3 - SCREWDRIVER
Fig. 16 Switch In ON Position
1 - IGNITION SWITCH
2 - ROTATE TO ON POSITION
Fig. 17 Ignition Switch Removal/Installation
1 - TAMPER PROOF SCREW
2 - IGNITION SWITCH
3 - ELECTRICAL CONNECTORS
WJCOLUMN 19 - 13
IGNITION SWITCH (Continued)

KEY-IN IGNITION SWITCH
DESCRIPTION
The key-in ignition switch is concealed within and
integral to the ignition switch, which is mounted on
the steering column. The key-in ignition switch is
actuated by the ignition lock cylinder mechanism,
and is hard wired between a body ground and the
Body Control Module (BCM) through the instrument
panel wire harness.
The key-in ignition switch cannot be adjusted or
repaired and, if faulty or damaged, the entire igni-
tion switch unit must be replaced,(Refer to 19 -
STEERING/COLUMN/LOCK CYLINDER HOUSING
- REMOVAL). For complete circuit diagrams, refer to
Body Control Modulein the Contents of Wiring
Diagrams.
OPERATION
The key-in ignition switch closes a path to ground
for the BCM when the ignition key is inserted in the
ignition lock cylinder, and opens the ground path
when the key is removed from the ignition lock cyl-
inder. The BCM monitors the key-in ignition switch
status through an internal pull-up, then sends the
proper switch status messages to other electronic
modules over the Programmable Communications
Interface (PCI) data bus network. The key-in ignition
switch status is also used by the BCM as an input
for chime warning system operation.
DIAGNOSIS AND TESTING
KEY-IN IGNITION SWITCH
For complete circuit diagrams, refer toBody Con-
trol Modulein the Contents of Wiring Diagrams.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO GROUP 8M - PASSIVE
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING WHEEL, STEERING COLUMN, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.(1) Disconnect and isolate the battery negative
cable. Disconnect the instrument panel wire harness
connector from the key-in ignition switch connector
receptacle on the ignition switch. Check for continu-
ity between the key-in ignition switch sense and
ground terminals of the key-in ignition switch con-
nector receptacle. There should be continuity with
the key inserted in the ignition lock cylinder, and no
continuity with the key removed from the ignition
lock cylinder. If OK, go to Step 2. If not OK, replace
the faulty ignition switch unit.
(2) Check for continuity between the ground cir-
cuit cavity of the instrument panel wire harness con-
nector for the key-in ignition switch and a good
ground. There should be continuity. If OK, go to Step
3. If not OK, repair the open ground circuit to ground
as required.
(3) Disconnect the gray 26-way instrument panel
wire harness connector from the Body Control Mod-
ule (BCM) connector receptacle. Check for continuity
between the key-in ignition switch sense circuit cav-
ity of the instrument panel wire harness connector
for the key-in ignition switch and a good ground.
There should be no continuity. If OK, go to Step 4. If
not OK, repair the shorted key-in ignition switch
sense circuit as required.
(4) Check for continuity between the key-in igni-
tion switch sense circuit cavities of the instrument
panel wire harness connector for the key-in ignition
switch and the gray 26-way instrument panel wire
harness connector for the BCM. There should be con-
tinuity. If OK, use a DRB scan tool and the proper
Diagnostic Procedures manual to test the BCM. If
not OK, repair the open key-in ignition switch sense
circuit as required.
LOCK CYLINDER
REMOVAL
The ignition key must be in the key cylinder for
cylinder removal. The key cylinder must be removed
first before removing ignition switch.
(1) Disconnect negative battery cable at battery.
(2) If equipped with an automatic transmission,
place shifter in PARK position.
(3) Rotate key to ON position.
19 - 14 COLUMNWJ

(4) A release tang is located on bottom of key cyl-
inder (Fig. 18).(5) Position a small screwdriver or pin punch into
tang access hole on bottom of steering column lower
cover (Fig. 19).
(6) Push the pin punch up while pulling key cylin-
der from steering column.
INSTALLATION
The ignition key must be in the key cylinder for
cylinder removal. The key cylinder must be removed
first before removing ignition switch.
(1) If equipped with an automatic transmission,
place shifter in PARK position.
(2) Position key cylinder into steering column as it
would normally be in the ON position.
(3) Press key cylinder into column until it snaps
into position.
(4) Check mechanical operation of switch.Auto-
matic Transmission:Be sure transmission lever is
locked in PARK position after key removal. If key is
difficult to rotate or is difficult to remove, the shift
lever-to-steering column cable may be out of adjust-
ment or defective. Refer to Transmission for proce-
dures.Manual Transmission:Be sure key cannot
be removed until release lever is operated. If key can
be removed, release lever mechanism may be defec-
tive. Release lever mechanism is not serviced sepa-
rately. If repair is necessary, the steering column
must be replaced,(Refer to 19 - STEERING/COL-
UMN - REMOVAL).
(5) Connect negative cable to battery.
(6) Check electrical operation of switch.
STEERING WHEEL
REMOVAL
For steering wheel removal procedure,(Refer to 8 -
ELECTRICAL/RESTRAINTS/CLOCKSPRING -
REMOVAL).
INSTALLATION
For steering wheel installation procedure,(Refer to
8 - ELECTRICAL/RESTRAINTS/CLOCKSPRING -
INSTALLATION).
Fig. 18 Key Cylinder Release Tang
1 - KEY CYLINDER
2 - RELEASE TANG
Fig. 19 Key Cylinder and Cover Removal
1 - LOWER COVER
2 - ACCESS HOLE
3 - PIN PUNCH
4 - COVER SCREWS (3)
WJCOLUMN 19 - 15
LOCK CYLINDER (Continued)

CLUTCH AND BAND APPLICATION CHART
SHIFT
LEVER
POSI-
TIONTRANSMISSION CLUTCHES AND BANDS OVERDRIVE CLUTCHES
FRONT
CLUTCHFRONT
BANDREAR
CLUTCHREAR
BANDOVER-
RUNNING
CLUTCHOVER-
DRIVE
CLUTCHDIRECT
CLUTCHOVER-
RUNNING
CLUTCH
Reverse X X X
Drive -
FirstXXXX
Drive -
SecondXX X X
Drive -
ThirdXX XX
Drive -
FourthXX X
Manual
SecondXXXXX
Manual
FirstXX X X X
Note that the rear clutch is applied in all forward
ranges (D, 2, 1). The transmission overrunning clutch
is applied in first gear (D, 2 and 1 ranges) only. The
rear band is applied in 1 and R range only.
Note that the overdrive clutch is applied only in
fourth gear and the overdrive direct clutch and over-
running clutch are applied in all ranges except fourth
gear.
For example: If slippage occurs in first gear in D
and 2 range but not in 1 range, the transmission
overrunning clutch is faulty. Similarly, if slippage
occurs in any two forward gears, the rear clutch is
slipping.
Applying the same method of analysis, note that
the front and rear clutches are applied simulta-
neously only in D range third and fourth gear. If the
transmission slips in third gear, either the front
clutch or the rear clutch is slipping.
If the transmission slips in fourth gear but not in
third gear, the overdrive clutch is slipping. By select-
ing another gear which does not use these clutches,
the slipping unit can be determined. For example, if
the transmission also slips in Reverse, the front
clutch is slipping. If the transmission does not slip in
Reverse, the rear clutch is slipping.
If slippage occurs during the 3-4 shift or only in
fourth gear, the overdrive clutch is slipping. Simi-
larly, if the direct clutch were to fail, the transmis-
sion would lose both reverse gear and overrun
braking in 2 position (manual second gear).
If the transmission will not shift to fourth gear, the
control switch, overdrive solenoid or related wiring
may also be the problem cause.This process of elimination can be used to identify
a slipping unit and check operation. Proper use of
the Clutch and Band Application Chart is the key.
Although road test analysis will help determine the
slipping unit, the actual cause of a malfunction usu-
ally cannot be determined until hydraulic and air
pressure tests are performed. Practically any condi-
tion can be caused by leaking hydraulic circuits or
sticking valves.
Unless a malfunction is obvious, such as no drive
in D range first gear, do not disassemble the trans-
mission. Perform the hydraulic and air pressure tests
to help determine the probable cause.
DIAGNOSIS AND TESTING - HYDRAULIC
PRESSURE TEST
Hydraulic test pressures range from a low of one
psi (6.895 kPa) governor pressure, to 300 psi (2068
kPa) at the rear servo pressure port in reverse.
An accurate tachometer and pressure test gauges
are required. Test Gauge C-3292 has a 100 psi range
and is used at the accumulator, governor, and front
servo ports. Test Gauge C-3293-SP has a 300 psi
range and is used at the rear servo and overdrive
ports where pressures exceed 100 psi.
Pressure Test Port Locations
Test ports are located at both sides of the transmis-
sion case (Fig. 9).
Line pressure is checked at the accumulator port
on the right side of the case. The front servo pressure
port is at the right side of the case just behind the
filler tube opening.
21 - 12 AUTOMATIC TRANSMISSION - 42REWJ
AUTOMATIC TRANSMISSION - 42RE (Continued)