2003 JEEP GRAND CHEROKEE instrument panel description

FuseandBatteryin the index in this service man-
ual for the location of additional service information
covering the ignition-off draw fuse and the battery.
FUSE COVER
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Pull down on the rear edge (nearest the rear of
the vehicle) of the instrument panel fuse cover until
the rear latches unsnap from the tabs on the lower
junction block housing and the side latch unsnaps
from the tab on the instrument panel steering col-
umn support bracket outboard of the 16-way data
link connector (Fig. 18).
(3) Move the instrument panel fuse cover towards
the front of the vehicle to disengage the front latches
from the mounting slots in the lower housing of the
body control module.
(4) Remove the fuse cover from under the instru-
ment panel.
INSTALLATION
(1) Position the two front latches of the instrument
panel fuse cover within the two locator channel for-
mations on the bottom of the body control module
housing (Fig. 19).
(2) While applying a slight upward pressure to the
instrument panel fuse cover over the front latches,
slowly slide the front latches through the locator
channels toward the front of the vehicle until thelatches exit the front of the locator channels. This
will locate the front latches at the mounting slots in
the lower housing of the body control module.
(3) Apply a slight rearward pressure on the instru-
ment panel fuse cover to engage the front latches in
the mounting slots in the lower housing of the body
control module.
(4) Swing the rear edge (nearest the rear of the
vehicle) of the instrument panel fuse cover up toward
the junction block.
(5) Press firmly upward on the instrument panel
fuse cover over the rear latches until the latches
snap into place over the tabs on the lower edge of the
junction block housing.
(6) Press firmly upward on the 16-way data link
connector cover formation of the instrument panel
fuse cover until the side latch snaps into place over
the tab on the outboard side of the instrument panel
steering column support bracket.
(7) Reconnect the battery negative cable.
REAR POWER OUTLET
DESCRIPTION - REAR POWER OUTLET
A rear accessory power outlet is optional equip-
ment on this model. The rear power outlet is
installed in the lower right quarter trim panel near
the right liftgate opening pillar in the cargo area of
Fig. 18 Instrument Panel Fuse Cover Remove/Install
1 - REAR LATCHES
2 - JUNCTION BLOCK AND BODY CONTROL MODULE UNIT
3 - INSTRUMENT PANEL FUSE COVER
4 - SIDE LATCH
5 - FRONT LATCHES
Fig. 19 Instrument Panel Fuse Cover Locator
Channels
1 - JUNCTION BLOCK
2 - SCREWS (4)
3 - BODY CONTROL MODULE
4 - FUSE COVER LOCATOR CHANNELS
5 - FUSE COVER MOUNTING SLOTS
6 - INSTRUMENT PANEL WIRE HARNESS CONNECTORS
8W - 97 - 16 8W-97 POWER DISTRIBUTIONWJ
IOD WIRE HARNESS CONNECTOR (Continued)

(9) Lower the engine until it is properly located on
the engine mounts.
(10) Install the through bolts and tighten the nuts.
(11) Lower the jack stand and remove the piece of
wood.
(12) Install the engine flywheel and transmission
torque converter housing access cover.
(13) Install the engine starter motor. (Refer to 8 -
ELECTRICAL/STARTING/STARTER MOTOR -
INSTALLATION).
(14) Connect the exhaust pipe to the hanger and to
the engine exhaust manifold.
(15) Install transmission oil cooling lines (if
equipped) and oxygen sensor wiring supports that
attach to the oil pan studs.
(16) Install the oil pan drain plug (Fig. 81).
Tighten the plug to 34 N´m (25 ft. lbs.) torque.
(17) Lower the vehicle.
(18) Connect negative cable to battery.
(19) Fill the oil pan with engine oil to the specified
level.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR FAN. DO
NOT WEAR LOOSE CLOTHING.
(20) Start the engine and inspect for leaks.
ENGINE OIL PRESSURE
SENSOR
DESCRIPTION
The 3±wire, solid-state engine oil pressure sensor
(sending unit) is located in an engine oil pressure
gallery.
OPERATION
The oil pressure sensor uses three circuits. They
are:
²A 5±volt power supply from the Powertrain Con-
trol Module (PCM)
²A sensor ground through the PCM's sensor
return
²A signal to the PCM relating to engine oil pres-
sure
The oil pressure sensor has a 3±wire electrical
function very much like the Manifold Absolute Pres-
sure (MAP) sensor. Meaning different pressures
relate to different output voltages.
A 5±volt supply is sent to the sensor from the PCM
to power up the sensor. The sensor returns a voltage
signal back to the PCM relating to engine oil pres-
sure. This signal is then transferred (bussed) to theinstrument panel on either a CCD or PCI bus circuit
(depending on vehicle line) to operate the oil pressure
gauge and the check gauges lamp. Ground for the
sensor is provided by the PCM through a low-noise
sensor return.
OIL PUMP
REMOVAL
A gear-type oil pump is mounted at the underside
of the cylinder block opposite the No.4 main bearing.
(1) Drain the engine oil.
(2) Remove the oil pan (Refer to 9 - ENGINE/LU-
BRICATION/OIL PAN - REMOVAL).
(3) Remove the pump-to-cylinder block attaching
bolts. Remove the pump assembly with gasket (Fig.
82).
CAUTION: If the oil pump is not to be serviced, DO
NOT disturb position of oil inlet tube and strainer
assembly in pump body. If the tube is moved within
the pump body, a replacement tube and strainer
assembly must be installed to assure an airtight
seal.
Fig. 82 Oil Pump Assembly
1 - OIL FILTER ADAPTOR
2 - BLOCK
3 - GASKET
4 - OIL INLET TUBE
5 - OIL PUMP
6 - STRAINER ASSEMBLY
7 - ATTACHING BOLTS
9 - 56 ENGINE - 4.0LWJ
OIL PAN (Continued)

NOTE: When installing oil pan gasket/windage tray,
start four pan bolts at each corner before tightening
oil pickup tube. This will keep pan gasket in align-
ment.
(3) Install oil pump pick-up tube using a new
O-ring. First tighten bolt at O-ring end of tube to 28
N´m (20 ft. lbs.). Tighten remain tube support fasten-
ers to 28 N´m (20 ft. lbs.).
(4) Install oil pan and tighten fasteners to 15 N´m
(11 ft. lbs.) (Fig. 95).
(5) Reconnect transmission oil cooler lines to oil
pan stud bolt.
(6) Install starter (Refer to 8 - ELECTRICAL/
STARTING/STARTER MOTOR - INSTALLATION).
(7) Install exhaust system Y-pipe.
(8) Install structural cover (Refer to 9 - ENGINE/
ENGINE BLOCK/STRUCTURAL COVER - INSTAL-
LATION).
(9) Lower vehicle.
(10) Fill engine with proper amount of oil (Refer to
LUBRICATION & MAINTENANCE/FLUID TYPES -
SPECIFICATIONS).
(11) Connect negative cable to battery.
OIL PRESSURE SENSOR/
SWITCH
DESCRIPTION
The 3±wire, solid-state engine oil pressure sensor
(sending unit) is located in an engine oil pressure
gallery.
OPERATION
The oil pressure sensor uses three circuits. They are:
²A 5±volt power supply from the Powertrain Con-
trol Module (PCM)
²A sensor ground through the PCM's sensor
return
²
A signal to the PCM relating to engine oil pressure
The oil pressure sensor has a 3±wire electrical
function very much like the Manifold Absolute Pres-
sure (MAP) sensor. Meaning different pressures
relate to different output voltages.
A 5±volt supply is sent to the sensor from the PCM
to power up the sensor. The sensor returns a voltage
signal back to the PCM relating to engine oil pres-
sure. This signal is then transferred (bussed) to the
instrument panel on either a CCD or PCI bus circuit
(depending on vehicle line) to operate the oil pressure
gauge and the check gauges lamp. Ground for the
sensor is provided by the PCM through a low-noise
sensor return.
REMOVAL
(1) Disconnect the negative cable from the battery.
(2) Raise vehicle on hoist.
(3) Remove front splash shield.
(4) Disconnect oil pressure sender wire (Fig. 96).
(5) Remove the pressure sender (Fig. 96).
INSTALLATION
(1) Install oil pressure sender.
(2) Connect oil pressure sender wire.
(3) Install front splash shield.
(4) Lower vehicle.
(5) Connect the negative battery cable.
Fig. 95 Oil Pan Tightening Sequence
Fig. 96 Oil Pressure Sending Unit
1 - BELT
2 - OIL PRESSURE SENSOR
3 - OIL FILTER
4 - ELEC. CONNECTOR
WJENGINE - 4.7L 9 - 133
OIL PAN (Continued)

(3) Apply a small amount of clean engine oil to
o-rings.
(4) Position filter/regulator to body and install 2
bolts. Tighten bolts to 3 N´m (30 in. lbs.) torque.
(5) Connect 3 fittings. Refer to Quick-Connect Fit-
tings.
(6) Connect negative battery cable to battery.
(7) Start engine and check for leaks.
FUEL LEVEL SENDING UNIT /
SENSOR
DESCRIPTION
The fuel gauge sending unit (fuel level sensor) is
attached to the side of the fuel pump module. The
sending unit consists of a float, an arm, and a vari-
able resistor track (card).
OPERATION
The fuel pump module has 4 different circuits
(wires). Two of these circuits are used for the fuel
gauge sending unit for fuel gauge operation, and for
certain OBD II emission requirements. The other 2
wires are used for electric fuel pump operation.
For Fuel Gauge Operation:A constant input
voltage source of about 12 volts (battery voltage) is
supplied to the resistor track on the fuel gauge send-
ing unit. This is fed directly from the Powertrain
Control Module (PCM).NOTE: For diagnostic pur-
poses, this 12V power source can only be veri-fied with the circuit opened (fuel pump module
electrical connector unplugged). With the con-
nectors plugged, output voltages will vary from
about 0.6 volts at FULL, to about 8.6 volts at
EMPTY (about 8.6 volts at EMPTY for Jeep
models, and about 7.0 volts at EMPTY for
Dodge Truck models).The resistor track is used to
vary the voltage (resistance) depending on fuel tank
float level. As fuel level increases, the float and arm
move up, which decreases voltage. As fuel level
decreases, the float and arm move down, which
increases voltage. The varied voltage signal is
returned back to the PCM through the sensor return
circuit.
Both of the electrical circuits between the fuel
gauge sending unit and the PCM are hard-wired (not
multi-plexed). After the voltage signal is sent from
the resistor track, and back to the PCM, the PCM
will interpret the resistance (voltage) data and send
a message across the multi-plex bus circuits to the
instrument panel cluster. Here it is translated into
the appropriate fuel gauge level reading. Refer to
Instrument Panel for additional information.
For OBD II Emission Monitor Requirements:
The PCM will monitor the voltage output sent from
the resistor track on the sending unit to indicate fuel
level. The purpose of this feature is to prevent the
OBD II system from recording/setting false misfire
and fuel system monitor diagnostic trouble codes.
The feature is activated if the fuel level in the tank
is less than approximately 15 percent of its rated
capacity. If equipped with a Leak Detection Pump
(EVAP system monitor), this feature will also be acti-
vated if the fuel level in the tank is more than
approximately 85 percent of its rated capacity.
DIAGNOSIS AND TESTING - FUEL LEVEL
SENDING UNIT
The fuel level sending unit contains a variable
resistor (track). As the float moves up or down, elec-
trical resistance will change. Refer to Instrument
Panel and Gauges for Fuel Gauge testing. To test the
gauge sending unit only, it must be removed from
vehicle. The unit is part of the fuel pump module.
Refer to Fuel Pump Module Removal/Installation for
procedures. Measure the resistance across the send-
ing unit terminals. With float in up position, resis-
tance should be 20 ohms (+/- 5%). With float in down
position, resistance should be 270 ohms (+/- 5%).
REMOVAL
The fuel gauge sending unit (fuel level sensor) and
float assembly is located on the side of fuel pump
module (Fig. 6). The fuel pump module is located
within the fuel tank.
Fig. 5 Fuel Filter/Fuel Pressure Regulator Removal/
Installation
1 - FUEL FILTER/FUEL PRESSURE REGULATOR
2 - MOUNTING BOLTS (2)
WJFUEL DELIVERY 14 - 7
FUEL FILTER/PRESSURE REGULATOR (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

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

WELD LOCATIONS
SPECIFICATIONS
WELD LOCATIONS
INDEX
DESCRIPTION FIGURE
RADIATOR SUPPORT BRACKETS 49
FRONT SUSPENSION SUPPORT REINFORCEMENT 50
FRONT LOWER CROSSMEMBER TO COWL SIDE PANEL 51
FRONT SILL TO LOWER CROSSMEMBER 52
FRONT FENDER MOUNTING BRACKET AND REINFORCEMENT 53
FRONT SUSPENSION SUPPORT TO SILLS AND COWL SIDE PANEL 54
LEFT INSTRUMENT PANEL BRACKET TO COWL SIDE PANEL 55
COWL SIDE UPPER REINFORCEMENT TO COWL SIDE AND FRONT SUSPENSION
SUPPORT56
COWL SIDE PANEL TO DASH PANEL AND INNER BODYSIDE PANEL AND SILL 57
PLENUM ASSEMBLY TO COWL SIDE PANEL 58
FRONT LOWER CROSSMEMBER 59
FRONT SUSPENSION SUPPORT TO DASH 60
WIPER MOUNTING BRACKETS TO PLENUM ASSEMBLY 61
COWL TOP AND PLENUM ASSEMBLY 62
LOWER PLENUM REINFORCEMENT TO LOWER PLENUM PANEL 63
DASH PANEL TO LOWER PLENUM PANEL 64
PLENUM ASSEMBLY TO COWL 65
COWL PANEL TO BODYSIDE SILL 66
COWL PANEL TO FRONT FLOOR PAN 67
FRONT SILLS TO DASH AND FRONT FLOOR PAN 68
COWL SIDE PANEL DASH INNER BODYSIDE AND OUTER BODYSIDE PANELS 69
UPPER FRONT INNER PILLAR TO ROOF AND COWL 70
DOOR OPENINGS 71
B-PILLAR REINFORCEMENT TO INNER BODYSIDE APERTURE 72
REAR QUARTER WINDOW TO BODYSIDE APERTURE INNER AND OUTER 73
LOWER REAR QUARTER TO BODYSIDE APERTURE INNER AND OUTER 74
INNER TRACK BAR, LOWER CONTROL ARM AND TRANSMISSION CROSSMEMBER
BRACKETS TO FRONT SILLS75
TRANSMISSION CROSSMEMBER BRACKET AND REINFORCEMENT TO FRONT
SILLS76
UPPER SILLS AND UPPER CONTROL ARM REINFORCEMENT AND BRACKETS TO
FRONT SILLS77
REINFORCEMENT TO FRONT OUTER SILLS 78
FRONT INNER SILL TO FRONT OUTER SILL 79
OUTER TRACK BAR BRACKET TO FRONT OUTER SILL 80
WJBODY STRUCTURE 23 - 153

HEATING & AIR CONDITIONING
TABLE OF CONTENTS
page page
HEATING & AIR CONDITIONING
DESCRIPTION
DESCRIPTION - COOLING SYSTEM
REQUIREMENTS.......................1
DESCRIPTION - HEATER AND AIR
CONDITIONER........................1
DESCRIPTION - REFRIGERANT SYSTEM
SERVICE PORT........................1
OPERATION
OPERATION - HEATER AND AIR
CONDITIONER........................2
OPERATION - REFRIGERANT SYSTEM
SERVICE PORT........................2DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - A/C
PERFORMANCE.......................2
DIAGNOSIS AND TESTING - HEATER
PERFORMANCE.......................6
STANDARD PROCEDURE - DIODE
REPLACEMENT.......................6
SPECIFICATIONS
A/C APPLICATION TABLE................7
TORQUE SPECIFICATIONS..............8
CONTROLS.............................9
DISTRIBUTION..........................36
PLUMBING.............................51
HEATING & AIR
CONDITIONING
DESCRIPTION
DESCRIPTION - COOLING SYSTEM
REQUIREMENTS
To maintain the performance level of the heating-
air conditioning system, the engine cooling system
must be properly maintained. The use of a bug
screen is not recommended. Any obstructions in front
of the radiator or condenser will reduce the perfor-
mance of the air conditioning and engine cooling sys-
tems.
The engine cooling system includes the heater core
and the heater hoses. Refer to Cooling for more infor-
mation before opening, or attempting any service to
the engine cooling system.
DESCRIPTION - HEATER AND AIR
CONDITIONER
A manual temperature control type heating-air
conditioning system is standard factory-installed
equipment on this model. An electronically controlled
Automatic Zone Control (AZC) type heating-air con-
ditioning system is an available factory-installed
option.
All vehicles are equipped with a common HVAC
housing assembly (Fig. 1). The system combines air
conditioning, heating, and ventilating capabilities in
a single unit housing mounted under the instrument
panel.DESCRIPTION - REFRIGERANT SYSTEM
SERVICE PORT
The two refrigerant system service ports are used
to charge, recover/recycle, evacuate, and test the air
conditioning refrigerant system. Unique service port
coupler sizes are used on the R-134a system to
ensure that the refrigerant system is not accidentally
contaminated by the use of the wrong refrigerant
(R-12), or refrigerant system service equipment.
Fig. 1 Blend-Air HVAC System - (typical)
1 - Blend Door
2 - Expansion Valve
3 - Evaporator Core
4 - Blower Assembly
5 - Recirculation Door
6 - Evaporator Probe
7 - Heater Core
8 - Heat/Defrost Door
9 - Panel/Defrost Door
WJHEATING & AIR CONDITIONING 24 - 1