2003 JEEP GRAND CHEROKEE Tire sensor

(e) Use DRB scan tool to power fuel pump. If
pressure is now within specifications, replace fuel
filter/fuel pressure regulator.
(f) If pressure is still low, replace fuel pump
module.
(4) If operating pressure is above 54.2 psi, electric
fuel pump is OK, but fuel pressure regulator is defec-
tive. Replace fuel filter/fuel pressure regulator.
(5) Install test port cap to fuel rail test port.
FUEL PUMP MODULE
DESCRIPTION
The fuel pump module is installed in the top of the
fuel tank (Fig. 16). The fuel pump module (Fig. 17)
contains the following components:
²A separate fuel pick-up filter (strainer)
²An electric fuel pump
²A threaded locknut to retain module to tank
²A gasket between tank flange and module
²Fuel gauge sending unit (fuel level sensor)²Fuel supply tube (line) connection
²Fuel return tube (line) connection
The fuel gauge sending unit and pick-up filter may
be serviced separately. If the electrical fuel pump
requires service, the entire fuel pump module must
be replaced.
OPERATION
Refer to Fuel Pump, Fuel Filter/Fuel Pressure Reg-
ulator and Fuel Gauge Sending Unit.
REMOVAL
Fuel tank removal will be necessary for fuel pump
module removal.
WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE (EVEN WITH THE ENGINE OFF).
BEFORE SERVICING FUEL PUMP MODULE, FUEL
SYSTEM PRESSURE MUST BE RELEASED.
(1) Perform Fuel System Pressure Release Proce-
dure.
Fig. 16 FUEL TANK AND COMPONENTS
1 - FUEL PUMP MODULE 9 - TANK SUPPORT BRACKET (SMALL/FRONT)
2 - MODULE LOCK RING 10 - MODULE PIGTAIL HARNESS
3 - TANK SUPPORT BRACKETS (REAR) 11 - FUEL SUPPLY (PRESSURE) LINE
4 - CHECK VALVE 12 - FUEL RETURN LINE
5 - FUEL FILL HOSE 13 - SKID PLATE
6 - ORVR COMPONENTS 14 - TANK STRAPS (2)
7 - ORVR CONTROL VALVE 15 - FUEL TANK
8 - CONTROL VALVE LOCK RING
WJFUEL DELIVERY 14 - 13
FUEL PUMP (Continued)

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)

TIRES/WHEELS
TABLE OF CONTENTS
page page
TIRES/WHEELS
DIAGNOSIS AND TESTING - TIRE AND
WHEEL RUNOUT......................1
STANDARD PROCEDURE
STANDARD PROCEDURE - TIRE AND
WHEEL BALANCE......................2
STANDARD PROCEDURE - MATCH
MOUNTING...........................4
STANDARD PROCEDURE - TIRE ROTATION . 5
STANDARD PROCEDURE - WHEEL
INSTALLATION........................5
TIRES
DESCRIPTION
DESCRIPTION - TIRES..................6
DESCRIPTION - RADIAL±PLY TIRES.......6
DESCRIPTION - TIRE INFLATION
PRESSURES..........................6
DESCRIPTION - TIRE PRESSURE FOR
HIGH SPEED..........................7
DESCRIPTION - REPLACEMENT TIRES.....7
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - PRESSURE
GAUGES.............................8
DIAGNOSIS AND TESTING - TREAD WEAR
INDICATORS..........................8
DIAGNOSIS AND TESTING - TIRE WEAR
PATTERNS...........................8
DIAGNOSIS AND TESTING - TIRE NOISE
OR VIBRATION........................8STANDARD PROCEDURE - REPAIRING
LEAKS...............................8
CLEANING.............................9
SPECIFICATIONS
TIRES...............................9
SPECIFICATIONS -.....................9
SPARE TIRE
DESCRIPTION - SPARE / TEMPORARY TIRE . . 10
WHEELS
DESCRIPTION.........................10
DIAGNOSIS AND TESTING - WHEEL
INSPECTION.........................10
STANDARD PROCEDURE - WHEEL
REPLACEMENT.......................10
SPECIFICATIONS
TORQUE CHART......................11
STUDS
REMOVAL.............................11
INSTALLATION.........................11
TIRE PRESSURE MONITORING
DESCRIPTION.........................12
OPERATION...........................12
DIAGNOSIS AND TESTING - TIRE PRESSURE
MONITORING SYSTEM.................12
SENSOR
REMOVAL - TIRE PRESSURE SENSOR/
TRANSMITTER.......................12
INSTALLATION - TIRE PRESSURE SENSOR/
TRANSMITTER.......................13
TIRES/WHEELS
DIAGNOSIS AND TESTING - TIRE AND WHEEL
RUNOUT
Radial runout is the difference between the high
and low points on the tire or wheel (Fig. 1).
Lateral runout is thewobbleof the tire or wheel.
Radial runout of more than 1.5 mm (.060 inch)
measured at the center line of the tread may cause
the vehicle to shake.
Lateral runout of more than 2.0 mm (.080 inch)
measured near the shoulder of the tire may cause the
vehicle to shake.
Sometimes radial runout can be reduced. Relocate
the wheel and tire assembly on the mounting studs
(See Method 1). If this does not reduce runout to an
acceptable level, the tire can be rotated on the wheel.
(See Method 2).
METHOD 1 (RELOCATE WHEEL ON HUB)
(1) Drive vehicle a short distance to eliminate tire
flat spotting from a parked position.
(2) Check wheel bearings and adjust if adjustable
or replace if necessary.
(3) Check the wheel mounting surface.
(4) Relocate wheel on the mounting, two studs
over from the original position.
(5) Tighten wheel nuts until all are properly
torqued, to eliminate brake distortion.
(6) Check radial runout. If still excessive, mark
tire sidewall, wheel, and stud at point of maximum
runout and proceed to Method 2.
METHOD 2 (RELOCATE TIRE ON WHEEL)
NOTE: Rotating the tire on wheel is particularly
effective when there is runout in both tire and
wheel.
WJTIRES/WHEELS 22 - 1

TIRE PRESSURE MONITORING
DESCRIPTION
The EVIC will monitor the tire pressure signals
from the five tire sensors and determine if any tire
has gone below the low pressure threshold or raised
above the high pressure threshold. Refer to the table
below.
LOW TIRE PRESSURE THRESHOLDS
SYSTEM STATUS
INDICATORTIRE PRESSURE
ON 179 kPa (26 PSI)
OFF 214 kPa (31 PSI)
HIGH TIRE PRESSURE THRESHOLDS
SYSTEM STATUS
INDICATORTIRE PRESSURE
ON 310 kPa (45 PSI)
OFF 276 kPa (40 PSI)
The Remote Tire Pressure Monitors (RTPM) are
not internally serviceable. For a Sensor Failure or
Low Battery fault, the RTPM must be replaced.
OPERATION
If equipped with the Tire Pressure Monitoring Sys-
tem, each of the vehicle's five wheels will have a
valve stem with a pressure sensor and radio trans-
mitter built in. Signals from the tire pressure sensors
are received and interpreted by the Electronic Vehi-
cle Information Center (EVIC). A sensor in a
mounted wheel will broadcast its detected pressure
once per minute when the vehicle is moving faster
than 40 km/h (25 mph). The spare tire sensor will
broadcast once every hour. Each sensor's broadcast is
uniquely coded so that the EVIC can determine loca-
tion. The individual tire pressures can be displayed
graphically on the EVIC
DIAGNOSIS AND TESTING - TIRE PRESSURE
MONITORING SYSTEM
All Tire Pressure Monitoring System Faults are
specific to one location. If a9BATTERY LOW9or
9SENSOR FAILURE9fault is detected, the location
will be displayed. The appropriate sensor/transmitter
can then be replaced. If a single sensor/transmitter
cannot be detected by the EVIC, replace that sensor
transmitter. If none of the sensors/transmitters can
be detected, refer to symptoms in the EVIC section.
For additional system description and diagnosis,
refer to Tire Pressure Monitoring in the Body Diag-
nostic manual.
SENSOR
REMOVAL - TIRE PRESSURE SENSOR/
TRANSMITTER
(1) Remove the tire/wheel from the vehicle.
CAUTION: When removing the stick on balancing
weights from the wheel, do not use an abrasive
cleaner or a cleaner which will damage the protec-
tive finish on the wheel.
(2) Remove the balancing weights from the wheel.
NOTE: The cap used on this valve stem contains an
O-ring seal to prevent contamination and moisture
from entering the valve stem. Retain this valve stem
cap for re-use. Do not substitute a regular valve
stem cap in its place.
(3) Remove the cap from the valve stem.
NOTE: The valve stem used on this vehicle is made
of aluminum and the core is nickel plated brass.
The original valve stem core must be reinstalled
and not substituted for a valve stem core made of a
different material. This is required to prevent corro-
sion in the valve stem caused by the different met-
als.
(4) Using the appropriate tool, remove the core
from the valve stem (Fig. 20).
(5) Let the tire fully deflate.
Fig. 20 REMOVING VALVE STEM CORE - TYPICAL
1 - WHEEL
2 - VALVE STEM
3 - TIRE
4 - VALVE STEM CORE TOOL
22 - 12 TIRES/WHEELSWJ

CAUTION: The pressure transmitter must be
removed from the wheel and dropped into the tire
prior to breaking the bead and dismounting the tire.
Failure to do this will greatly increase the risk of
damaging the pressure transducer when servicing
the tire.
(6) Remove nut mounting valve stem of pressure
sensor/transmitter to the wheel (Fig. 21). Drop sen-
sor/transmitter into tire.
CAUTION: When breaking the top and bottom bead
of the tire off the wheel, care must be used so the
bead breaking mechanism on the tire changer does
not damage the wheel. This includes the surface of
the wheel flange on the inside of the wheel.
(7) Using the tire changer manufacturers proce-
dure, first break down the upper bead of the tire.
Then break down the bottom bead of the tire.
CAUTION: When dismounting the upper tire bead
from the wheel, the proper procedure must be used.
Not using the proper procedure will result in dam-
age to the wheel and tire.(8) Dismount the upper bead of the tire from the
wheel.The upper bead must be fully dis-
mounted from the wheel to remove the tire
pressure transmitter from the inside of the tire.
The bottom bead of the tire does not need to be
removed from the wheel.
(9) Pull upward on the tire (Fig. 22). Reach into
the tire and remove the pressure sensor/transmitter
from inside the tire.
INSTALLATION - TIRE PRESSURE SENSOR/
TRANSMITTER
NOTE: When installing the tire pressure sensor/
transmitter, inspect the sealing O-ring at the bottom
of the valve stem for any sign of damage or deteri-
oration. Replace O-ring if necessary, before install-
ing the pressure transmitter on the wheel. Also, be
sure the surface of the wheel that the O-ring seals
against is clean and not damaged.
Fig. 21 VALVE STEM/PRESSURE TRANSMITTER -
TYPICAL
1 - NUT
2 - WHEEL
3 - TIRE
4 - VALVE STEM
Fig. 22 PRESSURE TRANSMITTER REMOVAL -
TYPICAL
1 - TIRE
2 - WHEEL
3 - PRESSURE TRANSMITTER
WJTIRES/WHEELS 22 - 13
SENSOR (Continued)

(1) Install the tire pressure sensor/transmitter on
the wheel (Fig. 23).
(2) Tighten the tire pressure sensor/transmitter
mounting nut to a torque of 11 N´m (97 in. lbs.) (Fig.
24). When tightening the sensor/transmitter nut,
hold the transmitter so it does not rotate. If the sen-
sor/transmitter rotates so the top edge is not level
with the wheel (Fig. 25), damage to the transmitter
will occur when mounting the tire. If the top edge of
the transmitter is not level with the wheel, it can be
rotated into position by lightly tapping it with your
hand.
CAUTION: When mounting the upper bead of the
extended mobility tire, the proper procedure must
be used. Not using the proper procedure will result
in damage to the wheel and tire.
(3) Mount the upper bead of the tire on the wheel.
(4) Install the original or an OEM replacement
valve stem cap on the valve stem.
(5) Using a soap solution, check that no air leak is
present where the valve stem mounts to the wheel.
(6) Balance the tire/wheel assembly using the cor-
rect procedure for using wheel flange mount and
stick-on wheel weights. For balancing information
and wheel weight positioning, (Refer to 22 - TIRES/
WHEELS - STANDARD PROCEDURE).
(7) Install the tire/wheel on the vehicle (Refer to
22 - TIRES/WHEELS - STANDARD PROCEDURE).
(8) Program the identification code for the new tire
pressure sensor/transmitter into the TPM module.(9) Verify that the TPM module has been pro-
grammed with the identification code from the new
tire pressure sensor/transmitter Refer to the appropi-
ate electrical section. If the identification code and
tire pressure thresholds from the new tire pressure
transmitter are present in the receivers memory the
new tire pressure transmitter has been correctly pro-
grammed to the receiver.
Fig. 23 TIRE PRESSURE SENSOR/TRANSMITTER -
TYPICAL
1 - WHEEL
2 - TIRE PRESSURE TRANSMITTER
Fig. 24 TIGHTENING SENSOR/TRANSDUCER -
TYPICAL
1 - TORQUE WRENCH
2 - WHEN TORQUING TRANSMITTER MOUNTING NUT DO NOT
LET THIS END OF TRANSMITTER ROTATE AWAY FROM THE
WHEEL
3 - WHEEL
4 - TIRE PRESSURE TRANSMITTER
Fig. 25 CORRECTLY POSITIONED SENSOR/TRAN -
TYPICAL
1 - THE TOP EDGES OF THE TIRE PRESSURE SENSOR/
TRANSMITTER MUST BE FLUSH WITH THE WHEEL HERE
2 - WHEEL
3 - TIRE PRESSURE SENSOR/TRANSMITTER
22 - 14 TIRES/WHEELSWJ
SENSOR (Continued)

Both the manual A/C Heater control panel and the
AZC control panel are serviced only as complete
units and cannot be repaired. If faulty or damaged,
the entire control panel unit must be replaced.
DIAGNOSIS AND TESTING - AUTOMATIC ZONE
CONTROL SYSTEM
The Automatic Zone Control (AZC) control module
has a system self-diagnostic mode which continuously
monitors various parameters during normal system
operation. If a system fault is detected, a current and
historical fault is recorded. When the current fault is
cleared, the historical fault remains until reset (man-
ually or automatically). Both the current and histor-
ical fault codes can be accessed through either the
front panel, or over the Programmable Communica-
tions Interface (PCI) bus using a DRBIIItscan tool,
and the appropriate diagnostic information.
The AZC control module is capable of three differ-
ent types of self-diagnostic tests, as follows:
²Fault Code Tests
²Input Circuit Tests
²Output Circuit/Actuator Tests
The information that follows describes:
²How to read the self-diagnostic display
²How to enter the AZC control module self-diag-
nostic test mode
²How to select the self-diagnostic test types
²How to perform the different tests
ENTERING THE AZC SELF-DIAGNOSTIC MODE
To enter the AZC self-diagnostic mode, perform the
following:
(1) Depress the a/c and recirc buttons at the same
time and hold. Rotate the left temperature control
knob clockwise (CW) one detent.
(2) If you continue to keep the a/c and recirc but-
tons depressed, the AZC control module will perform
a Segment Test of the Vacuum Fluorescent (VF) dis-
play. In the Segment Test you should see all of the
display segments illuminate as long as both buttons
are held. If a display segment fails to illuminate, the
vacuum fluorescent display is faulty and the a/c
heater control must be replaced.
(3) After viewing the Segment Test, release the
A/C and Recirc buttons and the display will clear
momentarily.Ifa0isdisplayed, then no faults
are set in the system.Should there be any faults,
either9current9or9historical9, all fault codes will be
displayed in ascending numerical sequence (note no
effort is made to display fault codes in chronological
order). Each fault code is displayed for one second
before the next code is displayed. Once all fault codes
have been displayed, the system will then repeat the
fault code numbers. This will continue until the left
side set temperature control is moved at least onedetent position in the CW direction or the ignition is
turned9OFF9.
FAULT CODE TESTS
Fault codes are two-digit numbers that identify a
circuit that is malfunctioning. There are two differ-
ent kinds of fault codes.
1.Current Fault Codes- Current means the
fault is present right now. There are two types of cur-
rent faults: input faults, and system faults.
2.Historical Fault Codes- Historical or stored
means that the fault occurred previously, but is not
present right now. A majority of historical fault codes
are caused by intermittent wire harness or wire har-
ness connector problems.
CURRENT FAULT CODES
Input faults 01 = IR thermister circuit
open
02 = IR thermister circuit
shorted
03 = Fan pot shorted
04 = Fan pot open
05 = Mode pot shorted
06 = Mode pot open
07 = IR sensor delta too
large
08 = Reserved
09 = Reserved
10 = One of four motor
drivers has drive9A9
shorted to ground
11 = Engine air intake
temperature Buss
message missing
12 = Country code Buss
message missing
24 - 18 CONTROLSWJ
A/C HEATER CONTROL (Continued)

ING & AIR CONDITIONING/CONTROLS/A/C
PRESSURE TRANSDUCER - INSTALLATION).
(9) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)
(10) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
(11) Connect the negative battery cable.
INSTALLATION
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
Any kinks or sharp bends in the refrigerant plumb-
ing will reduce the capacity of the entire air condi-
tioning system. Kinks and sharp bends reduce the
flow of refrigerant in the system. A good rule for the
flexible hose refrigerant lines is to keep the radius of
all bends at least ten times the diameter of the hose.
In addition, the flexible hose refrigerant lines should
be routed so they are at least 80 millimeters (3
inches) from the exhaust manifold.
High pressures are produced in the refrigerant sys-
tem when the air conditioning compressor is operat-
ing. Extreme care must be exercised to make sure
that each of the refrigerant system connections is
pressure-tight and leak free. It is a good practice to
inspect all flexible hose refrigerant lines at least once
a year to make sure they are in good condition and
properly routed.
(1) Remove the tape or plugs from the discharge
line block fitting and the manifold on the compressor.
Install the discharge line block fitting to the manifold
on the compressor. Tighten the mounting bolt to 25.4
N´m (225 in. lbs.).
(2) Remove the tape or plugs from the refrigerant
line fittings on the condenser inlet and the discharge
line. Connect the discharge line to the condenser
inlet. Tighten the retaining nut to 28 N´m (250 in.
lbs.).
(3) Install the a/c high pressure transducer(Refer
to 24 - HEATING & AIR CONDITIONING/CON-
TROLS/A/C PRESSURE TRANSDUCER - INSTAL-
LATION).
(4) Connect the battery negative cable.
(5) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)(6) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
A/C EXPANSION VALVE
DESCRIPTION
The ªHº valve type thermal expansion valve (TXV)
is located at the front of the heater-A/C housing
between the liquid and suction lines and the evapo-
rator coil.
The expansion valve is a factory calibrated unit
and cannot be adjusted or repaired. If faulty or dam-
aged, the expansion valve must be replaced.
OPERATION
High-pressure, high temperature liquid refrigerant
from the liquid line passes through the expansion
valve orifice, converting it inot a low-pressure, low-
temperature mixture of liquid and gas before it
enters the evaporator coil. A temperature sensor in
the expansion valve control head monitors the tem-
perature of the refrigerant leaving the evaporator coil
throught the suction line, and adjusts the orifice size
at the liquid line to let the proper amoount of refrig-
erant into the evaporator coil to meet the vehicle
cooling requirements. Controlling the refrigerant flow
through the evaporator ensures that none of the
refrigerant leaving the evaporator is still in a liquid
state, which could damage the compressor.
DIAGNOSIS AND TESTING - A/C EXPANSION
VALVE
The expansion valve is located on the engine side
of the dash panel near the shock tower.
The expansion valve can fail in three different
positions (open, closed or restricted).
In an Open Position: this will result in a noisy
compressor or no cooling. The cause can be broken
spring, broken ball or excessive moisture in the A/C
system. If the spring or ball are found to be defective,
replace the expansion valve. If excessive moisture is
found in the A/C system, recycle the refrigerant.
In a Closed Position: There will be low suction
pressure and no cooling. This may be caused by a
failed power dome or excessive moisture in the A/C
system. If the power dome on the expansion valve is
found to be defective replace the expansion valve. If
excessive moisture is found recycle the refrigerant.
A Restricted Orifice: There will be low suction
pressure and no cooling. This may be caused by
debris in the refrigerant system. If debris is believed
to be the cause, recycle the refrigerant and replace
the expansion valve and the receiver/drier.
WJPLUMBING 24 - 65
A/C DISCHARGE LINE (Continued)