2003 JEEP GRAND CHEROKEE 23 Body

depressed, pull fitting from component.The plas-
tic retainer ring must be pressed squarely
into fitting body. If this retainer is cocked
during removal, it may be difficult to discon-
nect fitting. Use an open-end wrench on
shoulder of plastic retainer ring to aid in dis-
connection.
(b) After disconnection, plastic retainer ring will
remain with quick-connect fitting connector body.
(c) Inspect fitting connector body, plastic retainer
ring and fuel system component for damage.
Replace as necessary.(9)Latch Clips:Depending on vehicle model and
engine, 2 different types of safety latch clips are used
(Fig. 50) or (Fig. 51). Type-1 is tethered to fuel line
and type-2 is not. A special tool will be necessary to
disconnect fuel line after latch clip is removed. The
latch clip may be used on certain fuel line/fuel rail
connection, or to join fuel lines together.
Fig. 46 DISCONNECTING SINGLE-TAB TYPE
FITTING
1 - PULL TAB
2 - SCREWDRIVER
3 - QUICK-CONNECT FITTING
Fig. 47 REMOVING PULL TAB
1 - FUEL TUBE OR FUEL SYSTEM COMPONENT
2 - PULL TAB
3 - QUICK-CONNECT FITTING
4 - FUEL TUBE STOP
Fig. 48 TYPICAL 2±TAB TYPE FITTING
1 - TAB(S)
2 - QUICK-CONNECT FITTING
Fig. 49 PLASTIC RETAINER RING TYPE FITTING
1 - FUEL TUBE
2 - QUICK CONNECT FITTING
3 - PUSH
4 - PLASTIC RETAINER
5 - PUSH
6 - PUSH
7 - PUSH
8 - PUSH
WJFUEL DELIVERY 14 - 29
QUICK CONNECT FITTING (Continued)

(a) Type 1: Pry up on latch clip with a screw-
driver (Fig. 50).
(b) Type 2: Separate and unlatch 2 small arms
on end of clip (Fig. 51) and swing away from fuel
line.
(c) Slide latch clip toward fuel rail while lifting
with screwdriver.
(d) Insert special fuel line removal tool (Snap-On
number FIH 9055-1 or equivalent) into fuel line(Fig. 52). Use tool to release locking fingers in end
of line.
(e) With special tool still inserted, pull fuel line
from fuel rail.
(f) After disconnection, locking fingers will
remain within quick-connect fitting at end of fuel
line.
(10) Disconnect quick-connect fitting from fuel sys-
tem component being serviced.
CONNECTING
(1) Inspect quick-connect fitting body and fuel sys-
tem component for damage. Replace as necessary.
(2) Prior to connecting quick-connect fitting to
component being serviced, check condition of fitting
and component. Clean parts with a lint-free cloth.
Lubricate with clean engine oil.
(3) Insert quick-connect fitting into fuel tube or
fuel system component until built-on stop on fuel
tube or component rests against back of fitting.
(4) Continue pushing until a click is felt.
(5) Single-tab type fitting: Push new tab down
until it locks into place in quick-connect fitting.
(6) Verify a locked condition by firmly pulling on
fuel tube and fitting (15-30 lbs.).
(7) Latch Clip Equipped: Install latch clip (snaps
into position).If latch clip will not fit, this indi-
cates fuel line is not properly installed to fuel
rail (or other fuel line). Recheck fuel line con-
nection.
(8) Connect negative cable to battery.
(9) Start engine and check for leaks.
Fig. 50 LATCH CLIP-TYPE 1
1 - TETHER STRAP
2 - FUEL LINE
3 - SCREWDRIVER
4 - LATCH CLIP
5 - FUEL RAIL
Fig. 51 LATCH CLIP-TYPE 2
1 - LATCH CLIP
Fig. 52 FUEL LINE DISCONNECTION USING
SPECIAL TOOL
1 - SPECIAL FUEL LINE TOOL
2 - FUEL LINE
3 - FUEL RAIL
14 - 30 FUEL DELIVERYWJ
QUICK CONNECT FITTING (Continued)

FUEL INJECTION
TABLE OF CONTENTS
page page
FUEL INJECTION
DIAGNOSIS AND TESTING
VISUAL INSPECTION..................32
SPECIFICATIONS
TORQUE - FUEL INJECTION.............39
ACCELERATOR PEDAL
REMOVAL.............................39
INSTALLATION.........................39
CRANKSHAFT POSITION SENSOR
DESCRIPTION
DESCRIPTION - 4.0L...................40
DESCRIPTION - 4.7L...................40
OPERATION
OPERATION - 4.0L....................40
OPERATION - 4.7L....................41
REMOVAL
REMOVAL - 4.0L......................41
REMOVAL - 4.7L......................41
INSTALLATION
INSTALLATION - 4.0L..................42
INSTALLATION - 4.7L..................43
FUEL INJECTOR
DESCRIPTION.........................43
OPERATION
OPERATION.........................43
OPERATION - PCM OUTPUT............43
DIAGNOSIS AND TESTING - FUEL INJECTOR . 44
REMOVAL.............................44
INSTALLATION.........................44
FUEL PUMP RELAY
DESCRIPTION.........................44
OPERATION...........................44
IDLE AIR CONTROL MOTOR
DESCRIPTION.........................44
OPERATION...........................44
REMOVAL
REMOVAL - 4.0L......................45
REMOVAL - 4.7L......................45
INSTALLATION
INSTALLATION - 4.0L..................46
INSTALLATION - 4.7L..................46
INTAKE AIR TEMPERATURE SENSOR
DESCRIPTION.........................46
OPERATION...........................46
REMOVAL
REMOVAL - 4.0L......................46
REMOVAL - 4.7L......................46
INSTALLATION
INSTALLATION - 4.0L..................47INSTALLATION - 4.7L..................47
MAP SENSOR
DESCRIPTION
DESCRIPTION........................48
DESCRIPTION - 4.7L...................48
OPERATION...........................48
REMOVAL
REMOVAL - 4.0L......................48
REMOVAL - 4.7L......................49
INSTALLATION
INSTALLATION - 4.0L..................49
INSTALLATION - 4.7L..................49
O2S HEATER RELAY
DESCRIPTION.........................49
OPERATION...........................49
REMOVAL.............................50
INSTALLATION.........................50
O2S SENSOR
DESCRIPTION.........................50
OPERATION...........................50
REMOVAL.............................51
INSTALLATION.........................51
THROTTLE BODY
DESCRIPTION.........................52
OPERATION...........................52
REMOVAL
REMOVAL - 4.0L......................52
REMOVAL - 4.7L......................53
INSTALLATION
INSTALLATION - 4.0L..................53
INSTALLATION - 4.7L..................54
THROTTLE CONTROL CABLE
REMOVAL
REMOVAL - 4.0L......................54
REMOVAL - 4.7L......................55
INSTALLATION
INSTALLATION ± 4.0L..................55
INSTALLATION - 4.7L..................56
THROTTLE POSITION SENSOR
DESCRIPTION.........................56
OPERATION...........................56
REMOVAL
REMOVAL - 4.0L......................57
REMOVAL - 4.7L......................57
INSTALLATION
INSTALLATION - 4.0L..................58
INSTALLATION - 4.7L..................58
WJFUEL INJECTION 14 - 31

(8) Inspect system body grounds for loose or dirty
connections. Refer to Group 8, Wiring for ground
locations.
(9) Verify crankcase ventilation (CCV) operation.
Refer to Emission Control System for additional
information.
(10) Inspect all fuel line quick-connect fittings for
damage or leaks.
(11) Verify hose connections to all ports of vacuum
fittings on intake manifold, and for emission system
are tight and not leaking.
(12) Inspect accelerator cable, transmission throt-
tle cable (if equipped) and speed control cable connec-
tions (if equipped). Check their connections to
throttle body linkage for any binding or restrictions.
(13) Verify vacuum booster hose is firmly con-
nected to fitting on intake manifold. Also check con-
nection to brake vacuum booster.(14) Inspect air cleaner inlet and air cleaner ele-
ment for dirt or restrictions.
(15) Inspect radiator grille area, radiator fins and
air conditioning condenser for restrictions.
(16) 4.0L Engine: Verify MAP, Intake Manifold Air
Temperature (IAT) sensor, TPS and Idle Air Control
(IAC) motor connectors are firmly connected (Fig. 9).
Be sure throttle body mounting bolts (Fig. 9)are
tight.
(17) 4.7L Engine: Verify Intake Manifold Air Tem-
perature (IAT) sensor, TPS and Idle Air Control (IAC)
motor connectors are firmly connected (Fig. 10). Be
sure throttle body mounting bolts (Fig. 10)are tight.
Fig. 8 Crankshaft Position SensorÐ4.7L V-8 Engine
1 - CRANKSHAFT POSITION SENSOR
2-STARTER
3 - ELEC. CONNECTOR
Fig. 9 IAT, MAP, IAC, TPS Sensor LocationsÐ4.0L
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 - 34 FUEL INJECTIONWJ
FUEL INJECTION (Continued)

(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)

(23) Inspect for pinched or leaking fuel tubes/lines.
Inspect for pinched, cracked or leaking fuel hoses.
(24) Inspect for exhaust system restrictions such
as pinched exhaust pipes, collapsed muffler or
plugged catalytic convertor.
(25) If equipped with automatic transmission, ver-
ify electrical harness is firmly connected to park/neu-
tral switch and to transmission components.
(26) Verify fuel pump module pigtail harness elec-
trical connector (Fig. 15) is firmly connected to body
harness connector.
(27) Inspect fuel line harness (from fuel pump
module) at fuel filter/fuel pressure regulator (Fig. 15)
for chaffing, cracks or leaks.
(28) Verify battery cable and solenoid feed wire
connections to starter solenoid are tight and clean.
(29) Inspect for chaffed wires or wires rubbing up
against other components.
(30) Inspect for chaffed vacuum lines or lines rub-
bing up against other components.
Fig. 15 Fuel Filter/Fuel Pressure Regulator Location
1 - FUEL RETURN LINE
2 - FUEL SUPPLY LINE (TO FUEL RAIL)
3 - FUEL FILTER/FUEL PRESSURE REGULATOR
4 - FUEL PRESSURE LINE
5 - REAR AXLE
6 - ELEC. CONNECTOR
7 - EVAP LINE
14 - 38 FUEL INJECTIONWJ
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

The PCM determines injector on-time (pulse width)
based on various inputs.
DIAGNOSIS AND TESTING - FUEL INJECTOR
To perform a complete test of the fuel injectors and
their circuitry, use the DRB scan tool and refer to the
appropriate Powertrain Diagnostics Procedures man-
ual. To test the injector only, refer to the following:
Disconnect the fuel injector wire harness connector
from the injector. The injector is equipped with 2
electrical terminals (pins). Place an ohmmeter across
the terminals. Resistance reading should be approxi-
mately 12 ohms  1.2 ohms at 20ÉC (68ÉF).
REMOVAL
WARNING: THE FUEL SYSTEM IS UNDER CON-
STANT PRESSURE EVEN WITH ENGINE OFF.
BEFORE SERVICING FUEL INJECTOR(S), FUEL
SYSTEM PRESSURE MUST BE RELEASED.
To remove one or more fuel injectors, the fuel rail
assembly must be removed from engine.
(1) Perform Fuel System Pressure Release Proce-
dure.
(2) Remove fuel injector rail. Refer to Fuel Injector
Rail Removal/Installation.
(3) Remove clip(s) retaining injector(s) to fuel rail
(Fig. 25).
(4) Remove injector(s) from fuel rail.
INSTALLATION
(1) Apply a small amount of engine oil to each fuel
injector o-ring. This will help in fuel rail installation.
(2) Install injector(s) and injector clip(s) to fuel
rail.
(3) Install fuel rail assembly. Refer to Fuel Injector
Rail Removal/Installation.
(4) Start engine and check for leaks.
FUEL PUMP RELAY
DESCRIPTION
The 5±pin, 12±volt, fuel pump relay is located in
the Power Distribution Center (PDC). Refer to the
label on the PDC cover for relay location.
OPERATION
The Powertrain Control Module (PCM) energizes
the electric fuel pump through the fuel pump relay.
The fuel pump relay is energized by first applying
battery voltage to it when the ignition key is turned
ON, and then applying a ground signal to the relay
from the PCM.
Whenever the ignition key is turned ON, the elec-
tric fuel pump will operate. But, the PCM will shut-
down the ground circuit to the fuel pump relay in
approximately 1±3 seconds unless the engine is oper-
ating or the starter motor is engaged.
IDLE AIR CONTROL MOTOR
DESCRIPTION
The IAC stepper motor is mounted to the throttle
body, and regulates the amount of air bypassing the
control of the throttle plate. As engine loads and
ambient temperatures change, engine rpm changes.
A pintle on the IAC stepper motor protrudes into a
passage in the throttle body, controlling air flow
through the passage. The IAC is controlled by the
Powertrain Control Module (PCM) to maintain the
target engine idle speed.
OPERATION
At idle, engine speed can be increased by retract-
ing the IAC motor pintle and allowing more air to
pass through the port, or it can be decreased by
restricting the passage with the pintle and diminish-
ing the amount of air bypassing the throttle plate.
The IAC is called a stepper motor because it is
moved (rotated) in steps, or increments. Opening the
IAC opens an air passage around the throttle blade
which increases RPM.Fig. 25 Fuel Injector MountingÐTypical (4.7L V-8
Engine Shown)
1 - INLET FITTING
2 - FUEL INJECTOR RAIL
3 - CLIP
4 - FUEL INJECTOR
14 - 44 FUEL INJECTIONWJ
FUEL INJECTOR (Continued)