sensor JEEP GRAND CHEROKEE 2003 WJ / 2.G Workshop Manual

(18) 4.0L Engine: Verify wire harness connector is
firmly connected to Engine Coolant Temperature
(ECT) sensor (Fig. 11).(19) 4.7L Engine: Verify MAP and Engine Coolant
Temperature (ECT) sensor electrical connectors are
firmly connected to sensors (Fig. 12).
(20) Verify fuel injector wire harness connectors
are firmly connected to injectors in correct order.
Each harness connector is numerically tagged with
injector number (INJ 1, INJ 2 etc.) of its correspond-
ing fuel injector and cylinder number.
(21) Raise and support vehicle.
(22) Verify all oxygen sensor wire connectors are
firmly connected to sensors. Inspect sensors and con-
nectors for damage (Fig. 13)or (Fig. 14).
Fig. 10 IAT, IAC, TPS Sensor LocationsÐ4.7L V-8
Engine
1 - MOUNTING BOLTS (3)
2 - THROTTLE BODY
3 - IAT SENSOR CONNECTOR
4 - IAC MOTOR CONNECTOR
5 - TPS CONNECTOR
Fig. 11 ECT Sensor LocationÐ4.0L Engine
1 - THERMOSTAT HOUSING
2 - ENGINE COOLANT TEMPERATURE SENSOR
3 - ELECTRICAL CONNECTOR
Fig. 12 MAP and ECT Sensor LocationsÐ4.7L V-8
Engine
1 - ECT SENSOR
2 - MOUNTING BOLTS (2)
3 - MAP SENSOR
4 - INTAKE MANIFOLD
WJFUEL INJECTION 14 - 35
FUEL INJECTION (Continued)

Fig. 13 Oxygen Sensor LocationsÐ4.0L Engine
14 - 36 FUEL INJECTIONWJ
FUEL INJECTION (Continued)

Fig. 14 Oxygen Sensor LocationsÐ4.7L V-8 Engine
WJFUEL INJECTION 14 - 37
FUEL INJECTION (Continued)

SPECIFICATIONS
TORQUE - FUEL INJECTION
DESCRIPTION N-m Ft. Lbs. In. Lbs.
Air Cleaner Housing Mount. Nuts 10 93
Air Cleaner Air Duct Clamps 4 35
Air Cleaner Resonator Bolts 4 35
Engine Coolant Temperature SensorÐ4.0L Engine 11 96
Engine Coolant Temperature SensorÐ4.7L Engine 11 96
Fuel Hose Clamps 1 10
IAC Motor-To-Throttle Body BoltsÐ4.0L Engine 7860
IAC Motor-To-Throttle Body BoltsÐ4.7L Engine 7 60
Intake Manifold Air Temp. SensorÐ4.0L Engine 28 20
Intake Manifold Air Temp. SensorÐ4.7L Engine 28 20
MAP Sensor Mounting ScrewsÐ4.0L Engine 3 25
MAP Sensor Mounting ScrewsÐ4.7L Engine 3 25
Oxygen SensorÐAll Engines 30 22
PCM-to-Mounting Bracket Screws 3 25
PCM-to-Mounting Bracket Screws 9 80
Radiator Cooling Fan Relay Bolts 3 25
Throttle Body Mounting BoltsÐ4.0L Engine 11 100
Throttle Body Mounting BoltsÐ4.7L Engine 12 105
TPS Mounting ScrewsÐ4.0L Engine 7 60
TPS Mounting ScrewsÐ4.7L Engine 7 60
ACCELERATOR PEDAL
REMOVAL
The accelerator pedal is connected to the throttle
body linkage by the throttle cable. The cable is pro-
tected by a plastic sheathing and is connected to the
throttle body linkage by a ball socket. It is connected
to the accelerator pedal arm by a plastic retainer
(clip) (Fig. 16). This retainer (clip) snaps into the top
of the accelerator pedal arm. A retainer clip (Fig. 16)
is also used to fasten cable to dash panel.
CAUTION: Be careful not to damage or kink the
cable core wire (within the cable sheathing) while
servicing accelerator pedal or throttle cable.
(1) From inside vehicle, hold up accelerator pedal.
Remove plastic cable retainer (clip) and throttle cable
core wire from upper end of pedal arm. Plastic cable
retainer (clip) snaps into pedal arm.
(2) Remove accelerator pedal bracket nuts. Remove
accelerator pedal assembly.
INSTALLATION
The accelerator pedal is connected to the throttle
body linkage by the throttle cable. The cable is pro-
tected by a plastic sheathing and is connected to the
throttle body linkage by a ball socket. It is connected
to the accelerator pedal arm by a plastic retainer
(clip) (Fig. 16) . This retainer (clip) snaps into the top
of the accelerator pedal arm. A retainer clip (Fig. 16)
is also used to fasten cable to dash panel.
(1) Place accelerator pedal assembly over studs
protruding from floor pan. Tighten mounting nuts to
12 N´m   2 N´m (105 in. lbs.   20 in. lbs.) torque.
(2) Slide throttle cable into opening in top of pedal
arm. Push plastic cable retainer (clip) into pedal arm
opening until it snaps into place.
(3) Before starting engine, operate accelerator
pedal to check for any binding.
WJFUEL INJECTION 14 - 39

CRANKSHAFT POSITION
SENSOR
DESCRIPTION
DESCRIPTION - 4.0L
The Crankshaft Position Sensor (CKP) is mounted
to the transmission bellhousing at the left/rear side
of the engine block (Fig. 17).
DESCRIPTION - 4.7L
The Crankshaft Position Sensor (CKP) is mounted
into the engine block above the starter motor (Fig.
18).
OPERATION
OPERATION - 4.0L
Engine speed and crankshaft position are provided
through the crankshaft position sensor. The sensor
generates pulses that are the input sent to the pow-
ertrain control module (PCM). The PCM interprets
the sensor input to determine the crankshaft posi-
tion. The PCM then uses this position, along withother inputs, to determine injector sequence and igni-
tion timing.
Fig. 16 Accelerator Pedal Mounting
1 - CLIP
2 - ACCELERATOR CABLE
3 - CABLE CONNECTOR
4 - MOUNTING NUTS (2)
5 - PEDAL/BRACKET ASSEMBLY
6 - MOUNTING STUDS (2)
Fig. 17 CKP Sensor LocationÐ4.0L 6-Cyl. Engine
1 - SLOTTED HOLE
2 - CRANKSHAFT POSITION SENSOR
3 - WIRE SHIELD
4 - MOUNTING BOLT
5 - TRANSMISSION HOUSING
6 - PAPER SPACER
Fig. 18 CKP Sensor LocationÐ4.7L V±8 Engine
1 - CRANKSHAFT POSITION SENSOR
2-STARTER
3 - ELEC. CONNECTOR
14 - 40 FUEL INJECTIONWJ
ACCELERATOR PEDAL (Continued)

The sensor is a hall effect device combined with an
internal magnet. It is also sensitive to steel within a
certain distance from it.
On 4.0L 6-cylinder engines, the flywheel/drive
plate has 3 sets of four notches at its outer edge (Fig.
19).
The notches cause a pulse to be generated when
they pass under the sensor. The pulses are the input
to the PCM. For each engine revolution there are 3
sets of four pulses generated.
The trailing edge of the fourth notch, which causes
the pulse, is four degrees before top dead center
(TDC) of the corresponding piston.
The engine will not operate if the PCM does not
receive a crankshaft position sensor input.
OPERATION - 4.7L
Engine speed and crankshaft position are provided
through the crankshaft position sensor. The sensor
generates pulses that are the input sent to the pow-
ertrain control module (PCM). The PCM interprets
the sensor input to determine the crankshaft posi-
tion. The PCM then uses this position, along with
other inputs, to determine injector sequence and igni-
tion timing.
The sensor is a hall effect device combined with an
internal magnet. It is also sensitive to steel within a
certain distance from it.On the 4.7L V±8 engine, a tonewheel is bolted to
the engine crankshaft (Fig. 20). This tonewheel has
sets of notches at its outer edge (Fig. 20).
The notches cause a pulse to be generated when
they pass under the sensor. The pulses are the input
to the PCM.
REMOVAL
REMOVAL - 4.0L
The Crankshaft Position (CKP) sensor is mounted
to the transmission bellhousing at the left/rear side
of the engine block (Fig. 21). The sensoris adjust-
ableand is attached with one bolt. A wire shield/
router is attached to the sensor (Fig. 21).
(1) Disconnect sensor pigtail harness (3±way con-
nector) from main engine wiring harness.
(2) Remove sensor mounting bolt.
(3) Remove wire shield and sensor.
REMOVAL - 4.7L
The Crankshaft Position (CKP) sensor is bolted to
the side of the engine cylinder block above the
starter motor (Fig. 22). It is positioned into a
machined hole at the side of the engine block.
(1) Remove starter motor. Refer to Starter Remov-
al/Installation.
Fig. 19 CKP Sensor OperationÐ4.0L 6-Cyl. Engine
1 - CRANKSHAFT POSITION SENSOR
2 - FLYWHEEL
3 - FLYWHEEL NOTCHES
Fig. 20 CKP Sensor Operation and TonewheelÐ4.7L
V±8 Engine
1 - TONEWHEEL
2 - NOTCHES
3 - CRANKSHAFT POSITION SENSOR
4 - CRANKSHAFT
WJFUEL INJECTION 14 - 41
CRANKSHAFT POSITION SENSOR (Continued)

(2) Disconnect CKP electrical connector at sensor
(Fig. 22).
(3) Remove CKP mounting bolt (Fig. 23).
(4) Carefully twist sensor from cylinder block.(5) Remove sensor from vehicle.
(6) Check condition of sensor o-ring.
INSTALLATION
INSTALLATION - 4.0L
The Crankshaft Position (CKP) sensor is mounted
to the transmission bellhousing at the left/rear side
of the engine block (Fig. 21). The sensoris adjust-
ableand is attached with one bolt. A wire shield/
router is attached to the sensor (Fig. 21).
New replacement sensors will be equipped with a
paper spacer glued to bottom of sensor. If installing
(returning) ausedsensor to vehicle, a new paper
spacer must be installed to bottom of sensor. This
spacer will be ground off the first time engine is
started. If spacer is not used, sensor will be broken
the first time engine is started.
(1) New Sensors: Be sure paper spacer is installed
to bottom of sensor. If not, obtain spacer
PN05252229.
(2) Used Sensors: Clean bottom of sensor and
install spacer PN05252229.
(3) Install sensor into transmission bellhousing
hole.
(4) Position sensor wire shield to sensor (Fig. 21).
Fig. 21 CKP SensorÐ4.0L 6-Cylinder Engine
1 - SLOTTED HOLE
2 - CRANKSHAFT POSITION SENSOR
3 - WIRE SHIELD
4 - MOUNTING BOLT
5 - TRANSMISSION HOUSING
6 - PAPER SPACER
Fig. 22 CKP Sensor LocationÐ4.7L V±8 Engine
1 - CRANKSHAFT POSITION SENSOR
2-STARTER
3 - ELEC. CONNECTOR
Fig. 23 CKP Sensor Removal/InstallationÐ4.7L V±8
Engine
1 - CRANKSHAFT POSITION SENSOR
2 - MOUNTING BOLT
14 - 42 FUEL INJECTIONWJ
CRANKSHAFT POSITION SENSOR (Continued)

(5) Push sensor against flywheel/drive plate. With
sensor pushed against flywheel/drive plate, tighten
mounting bolt to 7 N´m (60 in. lbs.) torque.
(6) Route sensor wiring harness into wire shield.
(7) Connect sensor pigtail harness electrical con-
nector to main wiring harness.
INSTALLATION - 4.7L
(1) Clean out machined hole in engine block.
(2) Apply a small amount of engine oil to sensor
o-ring.
(3) Install sensor into engine block with a slight
rocking action. Do not twist sensor into position as
damage to o-ring may result.
CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to cylinder
block. If sensor is not flush, damage to sensor
mounting tang may result.
(4) Install mounting bolt and tighten to 28 N´m
(21 ft. lbs.) torque.
(5) Connect electrical connector to sensor.
(6) Install starter motor. Refer to Starter Removal/
Installation.
FUEL INJECTOR
DESCRIPTION
A separate fuel injector (Fig. 24) is used for each
individual cylinder.
OPERATION
OPERATION
The fuel injectors are electrical solenoids. The
injector contains a pintle that closes off an orifice at
the nozzle end. When electric current is supplied to
the injector, the armature and needle move a short
distance against a spring, allowing fuel to flow out
the orifice. Because the fuel is under high pressure, a
fine spray is developed in the shape of a pencil
stream. The spraying action atomizes the fuel, add-
ing it to the air entering the combustion chamber.
The top (fuel entry) end of the injector (Fig. 24) is
attached into an opening on the fuel rail.
The nozzle (outlet) ends of the injectors are posi-
tioned into openings in the intake manifold just
above the intake valve ports of the cylinder head.
The engine wiring harness connector for each fuel
injector is equipped with an attached numerical tag
(INJ 1, INJ 2 etc.). This is used to identify each fuel
injector.
The injectors are electrically energized, individu-
ally and in a sequential order by the Powertrain Con-
trol Module (PCM). The PCM will adjust injector
pulse width by switching the ground path to each
individual injector on and off. Injector pulse width is
the period of time that the injector is energized. The
PCM will adjust injector pulse width based on vari-
ous inputs it receives.
Battery voltage is supplied to the injectors through
the ASD relay.
The PCM determines injector pulse width based on
various inputs.
OPERATION - PCM OUTPUT
The nozzle ends of the injectors are positioned into
openings in the intake manifold just above the intake
valve ports of the cylinder head. The engine wiring
harness connector for each fuel injector is equipped
with an attached numerical tag (INJ 1, INJ 2 etc.).
This is used to identify each fuel injector with its
respective cylinder number.
The injectors are energized individually in a
sequential order by the Powertrain Control Module
(PCM). The PCM will adjust injector pulse width by
switching the ground path to each individual injector
on and off. Injector pulse width is the period of time
that the injector is energized. The PCM will adjust
injector pulse width based on various inputs it
receives.
Battery voltage (12 volts +) is supplied to the injec-
tors through the ASD relay. The ASD relay will shut-
down the 12 volt power source to the fuel injectors if
the PCM senses the ignition is on, but the engine is
not running. This occurs after the engine has not
been running for approximately 1.8 seconds.
Fig. 24 Fuel InjectorÐ4.0L/4.7L Engines
1 - FUEL INJECTOR
2 - NOZZLE
3 - TOP (FUEL ENTRY)
WJFUEL INJECTION 14 - 43
CRANKSHAFT POSITION SENSOR (Continued)

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)

INSTALLATION
INSTALLATION - 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) Install sensor into intake manifold. Tighten
sensor to 28 N´m (20 ft. lbs.) torque.
(2) Connect electrical connector to sensor.
INSTALLATION - 4.7L
Threaded Type Sensor
(1) Install sensor (Fig. 28) into intake manifold.
Tighten sensor to 28 N´m (20 ft. lbs.) torque.
(2) Connect electrical connector to sensor.
Snap-In Type Sensor
(1) Check condition of sensor o-ring (Fig. 30).
(2) Clean sensor mounting hole in intake manifold.(3) Position sensor (Fig. 29) into intake manifold
and rotate clockwise until past release tab.
(4) Install electrical connector.
Fig. 28 IAT - 4.7L (THREADED TYPE)
1 - THROTTLE BODY
2 - TPS
3 - IAC MOTOR
4 - IAT SENSOR (THREADED TYPE)
5 - MOUNTING SCREWS
Fig. 29 IAT SENSOR - 4.7L (SNAP-IN TYPE)
1 - LEFT SIDE OF THROTTLE BODY
2 - ELEC. CONNECT.
3 - IAT SENSOR
4 - RELEASE TAB
Fig. 30 IAT SENSOR TAB / O-RING - 4.7L (SNAP-IN
TYPE)
1 - IAT SENSOR
2 - SENSOR O-RING
3 - RELEASE TAB
WJFUEL INJECTION 14 - 47
INTAKE AIR TEMPERATURE SENSOR (Continued)