2003 JEEP GRAND CHEROKEE compress

A/C COMPRESSOR CLUTCH - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 C2 18DB/YL A/C COMPRESSOR CLUTCH RELAY OUTPUT
2 Z18 18BK GROUND
A/C PRESSURE TRANSDUCER - BLACK 4 WAY
CAV CIRCUIT FUNCTION
1 K4 18BK/LB SENSOR GROUND
2 K6 18VT/WT (DIESEL) SENSOR REFERENCE VOLTAGE B
2 K6 18VT/BK (GAS) 5 VOLT SUPPLY
3 C18 18DB A/C PRESSURE SIGNAL
4- -
ACCELERATOR PEDAL POSITION SENSOR (DIESEL) - BLACK 10 WAY
CAV CIRCUIT FUNCTION
1- -
2 F855 18BR/YL SENSOR REFERENCE VOLTAGE A
3 K22 14RD/DB ACCELERATOR PEDAL POSITION SENSOR 2 SIGNAL
4- -
5- -
6 K225 18BK ACCELERATOR PEDAL POSITION SENSOR 2 GROUND
7 K81 20DB/DG ACCELERATOR PEDAL POSITION SENSOR 1 SIGNAL
8 K255 20WT/DG ACCELERATOR PEDAL POSITION SENSOR 1 GROUND
9- -
10 Y43 20WT/VT ACCELERATOR PEDAL POSITION SENSOR 1 5-VOLT
SUPPLY
ADJUSTABLE PEDALS MODULE (EXCEPT BUILT-UP-EXPORT) - GREEN 14 WAY
CAV CIRCUIT FUNCTION
1 Y151 20LG/BR ADJUSTABLE PEDALS SWITCH SENSE (FORWARD)
2 Y152 20LG/OR ADJUSTABLE PEDALS SWITCH SENSE (REARWARD)
3 Q110 16OR/VT ADJUSTABLE PEDALS MOTOR (FORWARD)
4 F72 16RD/YL FUSED B(+)
5- -
6 Q111 16OR/GY ADJUSTABLE PEDALS MOTOR (REARWARD)
7 Q113 20OR/DB (MEMORY) PEDAL POSITION SENSOR FEED
8 Q112 20OR/YL (MEMORY) PEDAL POSITION SENSOR SENSE
9 Q114 20OR/TN (MEMORY) PEDAL POSITION SENSOR RETURN
10 Z151 16BK GROUND
11 Z155 20BK/OR GROUND
12 L1 18WT/BR BACK-UP LAMP FEED
13 D25 20VT/YL PCI BUS
14 Y153 16DB/RD ADJUSTABLE PEDALS SWITCH FEED
8W - 80 - 6 8W-80 CONNECTOR PIN-OUTWJ

ENGINE CONTROL MODULE C1 (DIESEL) - BLACK 81 WAY
CAV CIRCUIT FUNCTION
55 B22 20DG/YL VEHICLE SPEED SENSOR SIGNAL
56 K225 18BK ACCELERATOR PEDAL POSITION SENSOR 2 GROUND
57 - -
58 K4 20BK/LB WATER IN FUEL SENSOR GROUND
59 K900 18GY INTAKE PORT SWIRL ACTUATOR SIGNAL
60 K7 20RD/WT FUEL PRESSURE SENSOR 5 VOLT SUPPLY
61 K51 20DB/YL AUTO SHUT DOWN RELAY CONTROL
62 - -
63 - -
64 - -
65 - -
66 - -
67 K173 20GY HYDRAULIC RADIATOR FAN SOLENOID CONTROL
68 - -
69 C13 20DB/RD A/C COMPRESSOR CLUTCH RELAY CONTROL
70 - -
71 - -
72 K236 20GY/PK GLOW PLUG RELAY NO. 2 CONTROL
73 - -
74 T752 20DG/RD ENGINE STARTER MOTOR RELAY CONTROL
75 K132 20BR/BK VISCOUS/CABIN HEATER RELAY CONTROL
76 Y42 20BR/BK WASTEGATE SOLENOID CONTROL
77 K152 20WT GLOW PLUG RELAY NO. 1 CONTROL
78 - -
79 - -
80 K46 20DB/BK FUEL PRESSURE SOLENOID CONTROL
81 K46 20DB/BK FUEL PRESSURE SOLENOID CONTROL
ENGINE CONTROL MODULE C2 (DIESEL) - BLACK 40 WAY
CAV CIRCUIT FUNCTION
82 D21 20PK SCI TRANSMIT
83 - -
84 - -
85 - -
86 - -
87 - -
88 - -
89 K35 20GY/YL EGR SOLENOID CONTROL
90 - -
91 - -
92 - -
93 - -
94 G123 20DG/WT WATER IN FUEL SENSOR SIGNAL
95 - -
96 - -
97 - -
98 - -
99 - -
100 - -
101 - -
102 - -
103 - -
104 - -
8W - 80 - 76 8W-80 CONNECTOR PIN-OUTWJ

POWERTRAIN CONTROL MODULE C3 (GAS) - GRAY 32 WAY
CAV CIRCUIT FUNCTION
1 C13 18DB/OR A/C COMPRESSOR CLUTCH RELAY CONTROL
2- -
3 K51 18DB/YL AUTO SHUT DOWN RELAY CONTROL
4 V36 18TN/RD SPEED CONTROL VACUUM SOLENOID CONTROL
5 V35 18LG/RD SPEED CONTROL VENT SOLENOID CONTROL
6- -
7 K42 18DB/LG (4.7L HIGH OUTPUT) KNOCK SENSOR NO. 1 SIGNAL
8 K99 18BR/OR OXYGEN SENSOR 1/1 HEATER CONTROL
9 K512 18RD/YL (EXCEPT 4.0L
BUILT-UP-EXPORT)OXYGEN SENSOR DOWNSTREAM RELAY CONTROL
10 K106 18WT/DG (EXCEPT
BUILT-UP-EXPORT)LEAK DETECTION PUMP SOLENOID CONTROL
11 V32 18OR/DG SPEED CONTROL SUPPLY
12 F42 18DG/LG FUSED AUTO SHUT DOWN RELAY OUTPUT
13 T10 18YL/DG (4.7L RHD) TORQUE MANAGEMENT REQUEST SENSE
13 T6 18OR/WT (4.0L LHD) OVERDRIVE OFF SWITCH SENSE
13 T10 18DG/LG (4.7L LHD) TORQUE MANAGEMENT REQUEST SENSE
13 T6 18OR/BK (4.0L RHD) OVERDRIVE OFF SWITCH SENSE
14 K107 18OR/PK (EXCEPT
BUILT-UP-EXPORT)LEAK DETECTION PUMP SWITCH SENSE
15 K25 18VT/LG BATTERY TEMPERATURE SENSOR SIGNAL
16 K299 18BR/WT OXYGEN SENSOR 1/2 HEATER CONTROL
17 - -
18 K142 18GY/BK (4.7L HIGH OUTPUT) KNOCK SENSOR NO. 2 SIGNAL
19 K31 18BR FUEL PUMP RELAY CONTROL
20 K52 18PK/BK DUTY CYCLE EVAP/PURGE SOLENOID CONTROL
21 - -
22 - -
23 - -
24 K29 18WT/PK SECONDARY BRAKE SWITCH SIGNAL
25 K125 18WT/DB GENERATOR SOURCE
26 K226 18LB/YL FUEL LEVEL SENSOR SIGNAL
27 D21 18PK SCI TRANSMIT
28 - -
29 D32 18LG (LHD) SCI RECEIVE
29 D32 18LG/DG (RHD) SCI RECEIVE
30 D25 18VT/YL PCI BUS
31 - -
32 V37 18RD/LG SPEED CONTROL SWITCH SIGNAL
RADIATOR FAN MOTOR - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 C23 12DG RADIATOR FAN RELAY OUTPUT
2 Z4 12BK/PK GROUND
8W - 80 - 110 8W-80 CONNECTOR PIN-OUTWJ

8W-91 CONNECTOR/GROUND/SPLICE LOCATION
TABLE OF CONTENTS
page
CONNECTOR/GROUND/SPLICE LOCATION
DESCRIPTION..........................1
CONNECTOR/GROUND/SPLICE
LOCATION
DESCRIPTION
This section provides illustrations identifying con-
nector, ground, and splice locations in the vehicle.Connector, ground, and splice indexes are provided.
Use the wiring diagrams in each section for connec-
tor, ground, and splice identification. Refer to the
appropriate index for the proper figure number. For
items that are not shown in this section N/S is placed
in the Fig. column.
CONNECTORS
CONNECTOR NAME/
NUMBERCOLOR LOCATION FIG.
A/C Compressor Clutch BK At A/C Compressor 9, 13
A/C Pressure Transducer BK Right Front of Engine Compartment 3, 4, 5
Accelerator Pedal Position
Sensor (Diesel)BK Rear of Engine Compartment Near
Fuel/Water Seperator7
Adjustable Pedals Module
(Except Built-up Export)GN Above Drivers Control Pedals N/S
Adjustable Pedals Motor/
Sensor Assembly (Except
Built-up Export)Above Drivers Control Pedals N/S
Adjustable Pedals Switch WT Drivers Lower Kick Panel 21
Airbag Control Module (ORC)
C1YL Below Center Floor Console, Near
Park Brake19, 20, 21, 22
Airbag Control Module (ORC)
C2YL Below Center Floor Console, Near
Park Brake19, 20, 21, 22
Ambient Temperature Sensor BK On Radiator Center Support 5
Antenna Module (Built-up-
export)WT Above Right Quarter Window N/S
Ash Receiver Lamp BK Below Cigarette Lighter 19, 20
Automatic Day/Night Mirror BK In Front of Rear View Mirror N/S
Automatic Headlamp Light
Sensor/VTSS LEDBK Near Left Instrument Panel Speaker 19, 20
Automatic Zone Control
Module - C1 (AZC)WT Left Side of HVAC Housing N/S
Automatic Zone Control
Module - C2 (AZC)WT Left Side of HVAC Housing N/S
Battery Temperature Sensor BK Below Battery Tray 4, 5
Blower Motor BK Behind Right Hand Side of
Instrument PanelN/S
WJ8W-91 CONNECTOR/GROUND/SPLICE LOCATION 8W - 91 - 1

SPLICES
SPLICE
NUMBERLOCATION FIG.
S100 Near T/O for Power Distribution Center Eyelet 2
S102 (4.0L) Near T/O for G103 10, 11
102 (4.7L) Near T/O for Fuel Injector No. 1 13
S102 (Diesel) Near T/O for C110 7, 8
S103 (4.7L) Near T/O for Engine Oil Pressure Sensor 13
S104 (4.0L) Near T/O for A/C Compressor Clutch N/S
S104 (4.7L) Near T/O for Oxygen Sensor 2/2 Downstream N/S
S105 (4.0L) Near T/O for Capacitor 10 11
S105 (4.7L) Near T/O for Fuel Injector NO. 7 13
S106 (4.0L) In T/O for Oxygen Sensors 11, 12
S106 (4.7L) Near T/O for C103 14
S106 (4.7L) RHD Near T/O for Fuel Injector No.4 15
S107 (4.0L) Near T/O for Fuel Injector No.5 9
S107 (4.7L) Near T/O for Fuel Injector No.7 13
S109 (4.0L) Near T/O for Fuel Injector No.2 9
S109 (4.7L) Near T/O for Coil On Plug No. 6 14, 15
S110 (4.0L
Except
Built-Up-Export)Near T/O for Oxygen Sensor N/S
S111 (4.7L) In T/O for Oxygen Sensor N/S
S111 (4.0L
Except
Built-Up-Export)Near T/O for Oxygen Sensor N/S
S112 (4.0L) Near T/O for C102, C103 and C104 10, 11
S112 (4.7L) Near T/O for Coil On Plug No.8 15
S112 (Diesel) Near T/O for Accelerator Pedal Position Sensor N/S
S113 (4.7L) Near T/O for Transmission Control Module 15, 18
S114 (4.0L) Near T/O for Transmission Control Module 18
S114 (4.7L) Near T/O for Transmission Control Module 15, 18
S115 (4.0L) Near T/O for Transmission Control Module 18
S115 (4.7L) Near T/O for Transmission Control Module 15, 18
S116 (4.0L) Near Powertrain Control Module C1 and C2 18
S116 (4.7L) LHD Near T/O for C102, C103 and C104 14
S116 (4.7L) RHD In T/O for Powertrain Control Module 15
S117 (4.7L) LHD Neat T/O for C102, C103 and C104 14
S118 (4.7L) Near T/O for Coil On PlugNo.4 14, 15
S118 (Diesel) Near T/O for Fuel Sender Unit N/S
S119 (4.7L) LHD In T/O for Crankshaft Position Sensor 18
S119 (4.7L) RHD In T/O for Powertrain Control Module 15
S120 (4.7L) Near T/O for Powertrain Control Module 15, 18
S121 (4.7L) Near T/O for Idle Air Control Motor 13
8W - 91 - 12 8W-91 CONNECTOR/GROUND/SPLICE LOCATIONWJ
CONNECTOR/GROUND/SPLICE LOCATION (Continued)

ENGINE
TABLE OF CONTENTS
page page
ENGINE - 4.0L............................ 1ENGINE - 4.7L........................... 61
ENGINE - 4.0L
TABLE OF CONTENTS
page page
ENGINE - 4.0L
DESCRIPTION..........................2
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - INTRODUCTION............3
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - PERFORMANCE............4
DIAGNOSIS AND TESTINGÐ ENGINE
DIAGNOSIS - MECHANICAL..............6
DIAGNOSIS AND TESTINGÐCYLINDER
COMPRESSION PRESSURE..............8
DIAGNOSIS AND TESTING - CYLINDER
COMBUSTION PRESSURE LEAKAGE.......8
DIAGNOSIS AND TESTINGÐREAR SEAL
AREA LEAKS..........................9
STANDARD PROCEDURE
STANDARD PROCEDURE - FORM-IN-
PLACE GASKETS AND SEALERS..........9
STANDARD PROCEDURE - REPAIR
DAMAGED OR WORN THREADS.........10
STANDARD PROCEDUREÐHYDROSTATIC
LOCK...............................10
STANDARD PROCEDURE - CYLINDER
BORE HONING.......................10
STANDARD PROCEDURE - ENGINE CORE
AND OIL GALLERY PLUGS..............11
REMOVAL.............................11
INSTALLATION.........................13
SPECIFICATIONS
ENGINE - 4.0L........................14
TORQUE - 4.0L ENGINE................17
AIR CLEANER ELEMENT
REMOVAL - 4.0L........................18
INSTALLATION - 4.0L....................19
AIR CLEANER HOUSING
REMOVAL - 4.0L........................19
INSTALLATION - 4.0L....................19CYLINDER HEAD
DESCRIPTION.........................19
REMOVAL.............................19
CLEANING............................21
INSPECTION..........................21
INSTALLATION.........................21
CYLINDER HEAD COVER(S)
DESCRIPTION.........................22
REMOVAL.............................22
CLEANING............................23
INSPECTION..........................23
INSTALLATION.........................23
INTAKE/EXHAUST VALVES & SEATS
DESCRIPTION.........................23
STANDARD PROCEDURE - VALVE SERVICE . . 23
REMOVAL.............................25
INSTALLATION.........................25
ROCKER ARM / ADJUSTER ASSEMBLY
DESCRIPTION.........................26
OPERATION...........................26
REMOVAL.............................26
CLEANING............................26
INSPECTION..........................27
INSTALLATION.........................27
VALVE STEM SEALS
DESCRIPTION.........................27
VALVE SPRINGS
DESCRIPTION.........................28
STANDARD PROCEDURE - VALVE SPRING
TENSION TEST.......................28
REMOVAL.............................28
INSTALLATION.........................29
ENGINE BLOCK
CLEANING............................30
INSPECTION..........................30
CAMSHAFT & BEARINGS
DESCRIPTION.........................30
WJENGINE 9 - 1

REMOVAL
REMOVAL - CAMSHAFT BEARINGS.......31
REMOVAL - CAMSHAFT................31
INSPECTION
INSPECTION - CAMSHAFT BEARINGS.....31
INSPECTION - CAMSHAFT..............31
INSTALLATION
INSTALLATION - CAMSHAFT BEARINGS . . . 32
INSTALLATION - CAMSHAFT............32
CONNECTING ROD BEARINGS
STANDARD PROCEDURE - FITTING
CONNECTING ROD BEARINGS..........33
CRANKSHAFT
DESCRIPTION.........................35
CRANKSHAFT MAIN BEARINGS
STANDARD PROCEDURE - FITTING
CRANKSHAFT MAIN BEARINGS..........36
REMOVAL.............................39
INSPECTION..........................40
INSTALLATION.........................40
CRANKSHAFT OIL SEAL - FRONT
REMOVAL.............................41
INSTALLATION.........................41
CRANKSHAFT OIL SEAL - REAR
REMOVAL.............................42
INSTALLATION.........................42
HYDRAULIC LIFTERS
DESCRIPTION.........................43
REMOVAL.............................43
CLEANING............................43
INSPECTION..........................43
INSTALLATION.........................43
PISTON & CONNECTING ROD
DESCRIPTION.........................44
STANDARD PROCEDURE - PISTON FITTING . 44
REMOVAL.............................45
INSTALLATION.........................46
PISTON RINGS
STANDARD PROCEDURE - PISTON RING
FITTING.............................47
VIBRATION DAMPER
REMOVAL.............................49
INSTALLATION.........................49STRUCTURAL SUPPORT
REMOVAL.............................49
INSTALLATION.........................50
LUBRICATION
DESCRIPTION.........................50
OPERATION...........................50
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE OIL
PRESSURE..........................51
DIAGNOSIS AND TESTING - ENGINE OIL
LEAK...............................51
OIL
STANDARD PROCEDURE - ENGINE OIL
SERVICE............................53
OIL FILTER
REMOVAL.............................53
INSTALLATION.........................54
OIL PAN
DESCRIPTION.........................54
REMOVAL.............................54
INSTALLATION.........................55
ENGINE OIL PRESSURE SENSOR
DESCRIPTION.........................56
OPERATION...........................56
OIL PUMP
REMOVAL.............................56
INSTALLATION.........................57
INTAKE MANIFOLD
DESCRIPTION.........................57
DIAGNOSIS AND TESTING - INTAKE
MANIFOLD LEAKAGE..................57
REMOVAL.............................57
INSTALLATION.........................57
EXHAUST MANIFOLD
DESCRIPTION.........................58
REMOVAL.............................58
INSTALLATION.........................58
TIMING BELT / CHAIN COVER(S)
REMOVAL.............................58
INSTALLATION.........................58
TIMING BELT/CHAIN AND SPROCKETS
REMOVAL.............................60
INSTALLATION.........................60
ENGINE - 4.0L
DESCRIPTION
The 4.0 Liter (242 CID) six-cylinder engine is an
In-line, lightweight, overhead valve engine. This
engine is designed for unleaded fuel.
The engine cylinder head has dual quench-type
combustion chambers that create turbulence and fast
burning of the air/fuel mixture. This results in better
fuel economy.
The cylinders are numbered 1 through 6 from front
to rear. The firing order is 1-5-3-6-2-4 (Fig. 1).The crankshaft rotation is clockwise, when viewed
from the front of the engine. The crankshaft rotates
within seven main bearings. The camshaft rotates
within four bearings.
The engine Build Date Code is located on a
machined surface on the right side of the cylinder
block between the No.2 and No.3 cylinders (Fig. 2).
The digits of the code identify:
²1st DigitÐThe year (8 = 1998).
²2nd & 3rd DigitsÐThe month (01 - 12).
²4th & 5th DigitsÐThe engine type/fuel system/
compression ratio (MX = A 4.0 Liter (242 CID) 8.7:1
compression ratio engine with a multi-point fuel
injection system).
9 - 2 ENGINE - 4.0LWJ

²6th & 7th DigitsÐThe day of engine build (01 -
31).(1)FOR EXAMPLE:Code * 801MX12 * identifies
a 4.0 Liter (242 CID) engine with a multi-point fuel
injection system, 8.7:1 compression ratio and built on
January 12, 1998.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - INTRODUCTION
Engine diagnosis is helpful in determining the
causes of malfunctions not detected and remedied by
routine maintenance.
These malfunctions may be classified as either
mechanical (e.g., a strange noise), or performance
(e.g., engine idles rough and stalls).
(Refer to 9 - ENGINE - DIAGNOSIS AND TEST-
ING - Preformance) or (Refer to 9 - ENGINE - DIAG-
NOSIS AND TESTING - Mechanical). Refer to 14 -
FUEL SYSTEM for fuel system diagnosis.
Additional tests and diagnostic procedures may be
necessary for specific engine malfunctions that can-
not be isolated with the Service Diagnosis charts.
Information concerning additional tests and diagno-
sis is provided within the following:
²Cylinder Compression Pressure Test (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING)
²Cylinder Combustion Pressure Leakage Test
(Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
²Cylinder Head Gasket Failure Diagnosis (Refer
to 9 - ENGINE/CYLINDER HEAD - DIAGNOSIS
AND TESTING)
²Intake Manifold Leakage Diagnosis (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
DIAGNOSIS AND TESTING)
²Lash Adjuster (Tappet) Noise Diagnosis (Refer to
9 - ENGINE/ENGINE BLOCK/HYDRAULIC LIFT-
ERS (CAM IN BLOCK) - DIAGNOSIS AND TEST-
ING)
²Engine Oil Leak Inspection (Refer to 9 -
ENGINE/LUBRICATION - DIAGNOSIS AND TEST-
ING)
Fig. 1 Engine Firing Order
Fig. 2 Build Date Code Location
1 - YEAR
2 - MONTH
3-DAY
WJENGINE - 4.0L 9 - 3
ENGINE - 4.0L (Continued)