2003 JEEP GRAND CHEROKEE Bolts

²a faulty or improperly adjusted switch that
allows a lamp to stay on. Refer to Ignition-Off Draw
Test in 8, Battery for more information.
INSPECTION
The Powertrain Control Module (PCM) monitors
critical input and output circuits of the charging sys-
tem, making sure they are operational. A Diagnostic
Trouble Code (DTC) is assigned to each input and
output circuit monitored by the On-Board Diagnostic
(OBD) system. Some charging system circuits are
checked continuously, and some are checked only
under certain conditions.
Refer to Diagnostic Trouble Codes in; Powertrain
Control Module; Electronic Control Modules for more
DTC information. This will include a complete list of
DTC's including DTC's for the charging system.
To perform a complete test of the charging system,
refer to the appropriate Powertrain Diagnostic Proce-
dures service manual and the DRBtscan tool. Per-
form the following inspections before attaching the
scan tool.(1) Inspect the battery condition. Refer to 8, Bat-
tery for procedures.
(2) Inspect condition of battery cable terminals,
battery posts, connections at engine block, starter
solenoid and relay. They should be clean and tight.
Repair as required.
(3) Inspect all fuses in both the fuseblock and
Power Distribution Center (PDC) for tightness in
receptacles. They should be properly installed and
tight. Repair or replace as required.
(4) Inspect generator mounting bolts for tightness.
Replace or tighten bolts if required. Refer to the Gen-
erator Removal/Installation section of this group for
torque specifications.
(5) Inspect generator drive belt condition and ten-
sion. Tighten or replace belt as required. Refer to
Belt Tension Specifications in 7, Cooling System.
(6) Inspect automatic belt tensioner (if equipped).
Refer to 7, Cooling System for information.
(7) Inspect generator electrical connections at gen-
erator field, battery output, and ground terminal (if
equipped). Also check generator ground wire connec-
tion at engine (if equipped). They should all be clean
and tight. Repair as required.
SPECIFICATIONS
GENERATOR RATINGS - GAS POWERED
TYPE PART NUMBER RATED SAE AMPS ENGINES MINIMUM TEST AMPS
BOSCH 56041322 136 4.0L 6-Cylinder 100
DENSO 56041324 136 4.7L V-8 100
TORQUE - GAS POWERED
DESCRIPTION N-m Ft. Lbs. In. Lbs.
Generator Mounting Bolts-4.0L 55 41
Generator Vertical Mounting Bolt-4.7L 40 29
Generator (long) Horizontal Mounting
Bolt-4.7L55 41
Generator (short) Horizontal Mounting
Bolt-4.7L55 41
Generator B+ Terminal Nut 11 95
WJCHARGING 8F - 25
CHARGING (Continued)

GENERATOR
DESCRIPTION
The generator is belt-driven by the engine using a
serpentine type drive belt. It is serviced only as a
complete assembly. If the generator fails for any rea-
son, the entire assembly must be replaced.
OPERATION
As the energized rotor begins to rotate within the
generator, the spinning magnetic field induces a cur-
rent into the windings of the stator coil. Once the
generator begins producing sufficient current, it also
provides the current needed to energize the rotor.
The Y type stator winding connections deliver the
induced AC current to 3 positive and 3 negative
diodes for rectification. From the diodes, rectified DC
current is delivered to the vehicle electrical system
through the generator battery terminal.
Although the generators appear the same exter-
nally, different generators with different output rat-
ings are used on this vehicle. Be certain that the
replacement generator has the same output rating
and part number as the original unit. Refer to Gen-
erator Ratings in the Specifications section at the
back of this group for amperage ratings and part
numbers.
Noise emitting from the generator may be caused
by: worn, loose or defective bearings; a loose or defec-
tive drive pulley; incorrect, worn, damaged or misad-
justed fan drive belt; loose mounting bolts; a
misaligned drive pulley or a defective stator or diode.
REMOVAL
WARNING: DISCONNECT NEGATIVE CABLE FROM
BATTERY BEFORE REMOVING BATTERY OUTPUT
WIRE (B+ WIRE) FROM GENERATOR. FAILURE TO
DO SO CAN RESULT IN INJURY OR DAMAGE TO
ELECTRICAL SYSTEM.
(1) Disconnect negative battery cable at battery.
(2) Remove generator drive belt. Refer to Cooling
System for procedure.
(3) Unsnap cable protector cover from B+ mount-
ing stud (Fig. 2) .
(4) Disconnect (unsnap) 2±wire field connector at
rear of generator (Fig. 2) .
(5) Remove generator mounting bolts (Fig. 3) or
(Fig. 4).
(6) Remove generator from vehicle.
Fig. 2 Generator B+ Cable and Field Wire
Connections (TypicalÐ4.0L Engine Shown)
1 - FIELD WIRE CONNECTOR
2 - B+ CABLE
3 - GENERATOR
4 - B+ CABLE MOUNTING NUT
5 - CABLE PROTECTOR
Fig. 3 Remove/Install GeneratorÐ4.7L V-8 Engine
1 - LOWER BOLTS
2 - REAR BOLT
3 - GENERATOR
WJCHARGING 8F - 27

INSTALLATION
(1) Position generator to engine and install mount-
ing bolts.
(2) Tighten generator mounting bolts as follows:
²Vertical mounting bolt 4.7L engineÐ40 N´m (29
ft. lbs.)
²Long horizontal mounting bolt 4.7L engineÐ55
N´m (41 ft. lbs.)
²Short horizontal mounting bolt 4.7L engineÐ55
N´m (41 ft. lbs.)
²Generator mounting bolts 4.0L engineÐ55 N´m
(41 ft. lbs.)
²B+ terminal nutÐ11 N´m (95 in. lbs.)
(3) Snap 2±wire field connector into rear of gener-
ator.
(4) Snap cable protector cover to B+ mounting
stud.
CAUTION: Never force a belt over a pulley rim
using a screwdriver. The synthetic fiber of the belt
can be damaged.
CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. The
water pump will be rotating in the wrong direction if
the belt is installed incorrectly, causing the engine
to overheat. Refer to belt routing label in engine
compartment, or refer to Belt Schematics in 7, Cool-
ing System.(5) Install generator drive belt. Refer to 7, Cooling
System for procedure.
(6) Install negative battery cable to battery.
VOLTAGE REGULATOR
DESCRIPTION
The Electronic Voltage Regulator (EVR) is not a
separate component. It is actually a voltage regulat-
ing circuit located within the Powertrain Control
Module (PCM). The EVR is not serviced separately. If
replacement is necessary, the PCM must be replaced.
OPERATION
The amount of DC current produced by the gener-
ator is controlled by EVR circuitry contained within
the PCM. This circuitry is connected in series with
the generators second rotor field terminal and its
ground.
Voltage is regulated by cycling the ground path to
control the strength of the rotor magnetic field. The
EVR circuitry monitors system line voltage (B+) and
battery temperature (refer to Battery Temperature
Sensor for more information). It then determines a
target charging voltage. If sensed battery voltage is
0.5 volts or lower than the target voltage, the PCM
grounds the field winding until sensed battery volt-
age is 0.5 volts above target voltage. A circuit in the
PCM cycles the ground side of the generator field up
to 100 times per second (100Hz), but has the capabil-
ity to ground the field control wire 100% of the time
(full field) to achieve the target voltage. If the charg-
ing rate cannot be monitored (limp-in), a duty cycle
of 25% is used by the PCM in order to have some
generator output. Also refer to Charging System
Operation for additional information.
Fig. 4 Remove/Install GeneratorÐ4.0L 6±Cylinder
Engine
1 - GENERATOR
2 - UPPER BOLT
3 - LOWER BOLT
8F - 28 CHARGINGWJ
GENERATOR (Continued)

SPECIFICATIONS
TORQUE - STARTER
DESCRIPTION N-m Ft. Lbs. In. Lbs.
Stater Motor (B+) Terminal
(Diesel)27 20
Stater Motor (B+) Terminal
(Except Diesel)11.3 100
Starter Motor Retaining Bolts
(Diesel)27 20
Starter Motor Retaining Bolt
(Forward Facing 4.0L)41 30
Starter Motor Retaining Bolt
(Forward Facing 4.7L)54 40
Starter Motor Retaining Bolt
(Rearward Facing 4.7L)54 40
STARTER MOTOR - GAS POWERED
Starter Motor and Solenoid
Manufacturer Mitsubishi
Engine Application 4.0L/4.7L
Power Rating 1.4 Kilowatt (1.9 Horsepower)
Voltage12 Volts
Number of Fields 4
Number of Poles 4
Number of Brushes 4
Drive Type Planetary Gear Reduction
Free Running Test Voltage 11.2 Volts
Free Running Test Maximum Amperage Draw 90 Amperes
Free Running Test Minimum Speed 2400 rpm
Solenoid Closing Maximum Voltage Required 7.8 Volts
*Cranking Amperage Draw Test 160 Amperes
*Test at operating temperature. Cold engine, tight (new) engine, or heavy oil will increase starter amperage draw.
STARTER MOTOR
DESCRIPTION
The starter motors used for both the 4.0L and the
4.7L engines available in this model are very similar,
but are not interchangeable. Both starter motors are
mounted with two screws to the automatic transmis-
sion torque converter housing and are located on the
right side of the engine.
Each of these starter motors incorporates several
of the same features to create a reliable, efficient,compact, lightweight and powerful unit. The electric
motors of both starters feature four electromagnetic
field coils wound around four pole shoes, and four
brushes contact the motor commutator. Both starter
motors are rated at 1.4 kilowatts (about 1.9 horse-
power) output at 12 volts.
Both of these starter motors are serviced only as a
unit with their starter solenoids, and cannot be
repaired. If either component is faulty or damaged,
the entire starter motor and starter solenoid unit
must be replaced.
WJSTARTING 8F - 35
STARTING (Continued)

IGNITION CONTROL
TABLE OF CONTENTS
page page
IGNITION CONTROL
DESCRIPTION..........................1
OPERATION............................1
SPECIFICATIONS
ENGINE FIRING ORDER - 4.0L 6-CYLINDER
ENGINE..............................2
ENGINE FIRING ORDERÐ4.7L V-8 ENGINE . . 2
IGNITION COIL RESISTANCE - 4.0L ENGINE . 2
IGNITION COIL RESISTANCEÐ4.7L V-8
ENGINE..............................2
IGNITION TIMING......................2
SPARK PLUGS........................3
TORQUE - IGNITION SYSTEM............3
AUTO SHUT DOWN RELAY
DESCRIPTION - PCM OUTPUT.............3
OPERATION
OPERATION - PCM OUTPUT.............3
OPERATION - ASD SENSE - PCM INPUT....4
REMOVAL.............................4
INSTALLATION..........................4
CAMSHAFT POSITION SENSOR
DESCRIPTION
DESCRIPTION - 4.0L....................4
DESCRIPTION - 4.7L....................5
OPERATION
OPERATION - 4.0L.....................5
OPERATION - 4.7L.....................5
REMOVAL
REMOVAL - 4.0L.......................6
REMOVAL - 4.7L.......................7INSTALLATION
INSTALLATION - 4.0L...................8
INSTALLATION - 4.7L...................9
COIL RAIL
DESCRIPTION..........................9
OPERATION...........................10
REMOVAL.............................10
INSTALLATION.........................11
IGNITION COIL
DESCRIPTION.........................11
OPERATION...........................12
REMOVAL.............................12
INSTALLATION.........................12
IGNITION COIL CAPACITOR
DESCRIPTION.........................13
OPERATION...........................13
REMOVAL.............................13
INSTALLATION.........................13
KNOCK SENSOR
DESCRIPTION.........................13
OPERATION...........................13
REMOVAL.............................14
INSTALLATION.........................15
SPARK PLUG
DESCRIPTION.........................15
DIAGNOSIS AND TESTING - SPARK PLUG
CONDITIONS.........................15
REMOVAL.............................18
CLEANING............................18
INSTALLATION.........................18
IGNITION CONTROL
DESCRIPTION
Two different ignition systems are used. One type
of system is for the 4.0L 6±cylinder engine. The other
is for the 4.7L V-8 engine.
OPERATION
The 4.0L 6±cylinder engine uses a one-piece coil
rail containing three independent coils. Although cyl-
inder firing order is the same as 4.0L engines of pre-
vious years, spark plug firing is not. The 3 coils dual-
fire the spark plugs on cylinders 1±6, 2±5 and/or 3±4.
When one cylinder is being fired (on compressionstroke), the spark to the opposite cylinder is being
wasted (on exhaust stroke). The one-piece coil bolts
directly to the cylinder head. Rubber boots seal the
secondary terminal ends of the coils to the top of all
6 spark plugs. One electrical connector (located at
the rear end of the coil rail) is used for all three coils.
The 4.7L V-8 engine uses 8 dedicated and individ-
ually fired coil for each spark plug. Each coil is
mounted directly to the top of each spark plug. A sep-
arate electrical connector is used for each coil.
Because of coil design, spark plug cables (second-
ary cables) are not used on either engine. Adistrib-
utor is not usedwith either the 4.0L or 4.7L
engines.
WJIGNITION CONTROL 8I - 1

SPARK PLUGS
ENGINE PLUG TYPE ELECTRODE GAP
4.0L 6-CYL. RC12ECC 0.89 mm (.035 in.)
4.7L V-8 (Exc. HO) RC12MCC4 1.01 mm (.040 in.)
4.7L V-8 High
Output (HO)RC7PYCB4 1.01 mm (.040 in.)
TORQUE - IGNITION SYSTEM
DESCRIPTION N-m Ft. Lbs. In. Lbs.
Crankshaft Position Sensor
Bolts - 4.0L Engine7- 60
Crankshaft Position Sensor
Bolt - 4.7L V-8 Engine28 21 -
Camshaft Position
Sensor±to±base bolts - 4.0L
Engine2- 15
Camshaft Position Sensor
Bolt - 4.7L V-8 Engine12 - 106
Oil Pump Drive Hold-down
Bolt - 4.0L Engine23 17 -
Ignition Coil Rail Mounting
Bolts - 4.0L Engine29 - 250
Ignition Coil Mounting Nut -
4.7L V-8 Engine8- 70
* Knock Sensor Bolt - 4.7L
HO V-8 Engine*20 *15 -
Spark Plugs - 4.0L Engine 35-41 26-30 -
Spark Plugs - 4.7L V-8
Engine24-30 18-22 -
* Do not apply any sealant,
thread-locker or adhesive to
bolts. Poor sensor
performance may result.
Refer to Removal / Installation
for additional information.
AUTO SHUT DOWN RELAY
DESCRIPTION - PCM OUTPUT
The 5±pin, 12±volt, Automatic Shutdown (ASD)
relay is located in the Power Distribution Center
(PDC). Refer to label on PDC cover for relay location.
OPERATION
OPERATION - PCM OUTPUT
The ASD relay supplies battery voltage (12+ volts)
to the fuel injectors and ignition coil(s). With certain
emissions packages it also supplies 12±volts to the
oxygen sensor heating elements.
The ground circuit for the coil within the ASD
relay is controlled by the Powertrain Control Module
(PCM). The PCM operates the ASD relay by switch-
ing its ground circuit on and off.
WJIGNITION CONTROL 8I - 3
IGNITION CONTROL (Continued)

The ASD relay will be shut±down, meaning the
12±volt power supply to the ASD relay will be de-ac-
tivated by the PCM if:
²the ignition key is left in the ON position. This
is if the engine has not been running for approxi-
mately 1.8 seconds.
²there is a crankshaft position sensor signal to
the PCM that is lower than pre-determined values.
OPERATION - ASD SENSE - PCM INPUT
A 12 volt signal at this input indicates to the PCM
that the ASD has been activated. The relay is used to
connect the oxygen sensor heater element, ignition
coil and fuel injectors to 12 volt + power supply.
This input is used only to sense that the ASD relay
is energized. If the Powertrain Control Module
(PCM) does not see 12 volts at this input when the
ASD should be activated, it will set a Diagnostic
Trouble Code (DTC).
REMOVAL
The ASD relay is located in the Power Distribution
Center (PDC) (Fig. 1). Refer to label on PDC cover
for relay location.
(1) Remove PDC cover.
(2) Remove relay from PDC.
(3) Check condition of relay terminals and PDC
connector terminals for damage or corrosion. Repair
if necessary before installing relay.
(4) Check for pin height (pin height should be the
same for all terminals within the PDC connector).
Repair if necessary before installing relay.
INSTALLATION
The ASD relay is located in the Power Distribution
Center (PDC) (Fig. 1). Refer to label on PDC cover
for relay location.
(1) Install relay to PDC.
(2) Install cover to PDC.
CAMSHAFT POSITION
SENSOR
DESCRIPTION
DESCRIPTION - 4.0L
The Camshaft Position Sensor (CMP) on the 4.0L
6±cylinder engine is bolted to the top of the oil pump
drive shaft assembly (Fig. 2). The sensor and drive
shaft assembly is located on the right side of the
engine near the oil filter (Fig. 3).
Fig. 1 Power Distribution Center (PDC) Location
1 - PCM
2 - COOLANT TANK
Fig. 2 CMP and Oil Pump Drive ShaftÐ4.0L Engine
1 - CAMSHAFT POSITION SENSOR
2 - MOUNTING BOLTS (2)
3 - PULSE RING
4 - DRIVE GEAR (TO CAMSHAFT)
5 - OIL PUMP DRIVESHAFT
6 - SENSOR BASE (OIL PUMP DRIVESHAFT ASSEMBLY)
8I - 4 IGNITION CONTROLWJ
AUTO SHUT DOWN RELAY (Continued)

DESCRIPTION - 4.7L
The Camshaft Position Sensor (CMP) on the 4.7L
V±8 engine is bolted to the front/top of the right cyl-
inder head (Fig. 4).
OPERATION
OPERATION - 4.0L
The CMP sensor contains a hall effect device called
a sync signal generator to generate a fuel sync sig-
nal. This sync signal generator detects a rotating
pulse ring (shutter) on the oil pump drive shaft (Fig.
2). The pulse ring rotates 180 degrees through the
sync signal generator. Its signal is used in conjunc-
tion with the crankshaft position sensor to differenti-
ate between fuel injection and spark events. It is also
used to synchronize the fuel injectors with their
respective cylinders.
When the leading edge of the pulse ring (shutter)
enters the sync signal generator, the following occurs:
The interruption of magnetic field causes the voltage
to switch high resulting in a sync signal of approxi-
mately 5 volts.When the trailing edge of the pulse ring (shutter)
leaves the sync signal generator, the following occurs:
The change of the magnetic field causes the sync sig-
nal voltage to switch low to 0 volts.
OPERATION - 4.7L
The CMP sensor contains a hall effect device called
a sync signal generator to generate a fuel sync sig-
nal. This sync signal generator detects notches
located on a tonewheel. The tonewheel is located at
the front of the camshaft for the right cylinder head
(Fig. 5). As the tonewheel rotates, the notches pass
through the sync signal generator. The pattern of the
notches (viewed counter-clockwise from front of
engine) is: 1 notch, 2 notches, 3 notches, 3 notches, 2
notches 1 notch, 3 notches and 1 notch. The signal
from the CMP sensor is used in conjunction with the
crankshaft position sensor to differentiate between
fuel injection and spark events. It is also used to syn-
chronize the fuel injectors with their respective cylin-
ders.
Fig. 3 CMP LocationÐ4.0L Engine
1 - OIL FILTER
2 - CAMSHAFT POSITION SENSOR
3 - CLAMP BOLT
4 - HOLD-DOWN CLAMP
5 - MOUNTING BOLTS (2)
6 - ELEC. CONNECTORFig. 4 CMP LocationÐ4.7L Engine
1 - RIGHT CYLINDER HEAD
2 - CAMSHAFT POSITION SENSOR
3 - MOUNTING BOLT
4 - ELEC. CONNECTOR
WJIGNITION CONTROL 8I - 5
CAMSHAFT POSITION SENSOR (Continued)