2003 JEEP GRAND CHEROKEE lamp

(6) Remove both horns and the mounting bracket
from the right extension of the radiator closure
assembly as a unit.
INSTALLATION
(1) Position both horns and the mounting bracket
onto the right extension of the radiator closure
assembly as a unit.
(2) Install and tighten the screw that secures the
horn mounting bracket to the right extension of the
radiator closure assembly. Tighten the screw to 11.3
N´m (100 in. lbs.).
(3) Reconnect the two right headlamp and dash
wire harness connectors to the horn connector recep-
tacles. Be certain to engage the connector lock tabs
after reconnecting them to the horn connector recep-
tacles.
(4) Install the lower front half of the inner liner to
the right front fender wheel house. (Refer to 23 -
BODY/EXTERIOR/FRONT FENDER - INSTALLA-
TION) for the procedure.
(5) Lower the vehicle.
(6) Reconnect the battery negative cable.
HORN RELAY
DESCRIPTION
The horn relay is a electromechanical device that
switches battery current to the horn when the horn
switch grounds the relay coil. The horn relay is
located in the Power Distribution Center (PDC) inthe engine compartment. If a problem is encountered
with a continuously sounding horn, it can usually be
quickly resolved by removing the horn relay from the
PDC until further diagnosis is completed. See the
fuse and relay layout label affixed to the inside sur-
face of the PDC cover for horn relay identification
and location.
The horn relay is a International Standards Orga-
nization (ISO) micro-relay. Relays conforming to the
ISO specifications have common physical dimensions,
current capacities, terminal patterns, and terminal
functions. The ISO micro-relay terminal functions
are the same as a conventional ISO relay. However,
the ISO micro-relay terminal pattern (or footprint) is
different, the current capacity is lower, and the phys-
ical dimensions are smaller than those of the conven-
tional ISO relay.
The horn relay cannot be repaired or adjusted and,
if faulty or damaged, it must be replaced.
OPERATION
The ISO relay consists of an electromagnetic coil, a
resistor or diode, and three (two fixed and one mov-
able) electrical contacts. The movable (common feed)
relay contact is held against one of the fixed contacts
(normally closed) by spring pressure. When the elec-
tromagnetic coil is energized, it draws the movable
contact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact.
When the electromagnetic coil is de-energized,
spring pressure returns the movable contact to the
normally closed position. The resistor or diode is con-
nected in parallel with the electromagnetic coil in the
relay, and helps to dissipate voltage spikes that are
produced when the coil is de-energized.
DIAGNOSIS AND TESTING - HORN RELAY
The horn relay (Fig. 2) is located in the Power Dis-
tribution Center (PDC) between the battery and the
right inner fender shield on the passenger side of the
engine compartment. If a problem is encountered
with a continuously sounding horn, it can usually be
quickly resolved by removing the horn relay from the
PDC until further diagnosis is completed. See the
fuse and relay layout label affixed to the inside sur-
face of the PDC cover for horn relay identification
and location. For complete circuit diagrams, refer to
the appropriate wiring information. The wiring infor-
mation includes wiring diagrams, proper wire and
connector repair procedures, details of wire harness
routing and retention, connector pin-out information
and location views for the various wire harness con-
nectors, splices and grounds.
Fig. 1 Horns Remove/Install
1 - RADIATOR CLOSURE ASSEMBLY
2 - HORNS AND MOUNTING BRACKET
3 - RIGHT HEADLAMP AND DASH WIRE HARNESS
CONNECTORS
8H - 4 HORNWJ
HORN (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)

REMOVAL
REMOVAL - 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. 6). The sensor and drive
shaft assembly is located on the right side of the
engine near the oil filter (Fig. 7).
The rotational position of oil pump drive deter-
mines fuel synchronization only. It does not deter-
mine ignition timing.
NOTE: Do not attempt to rotate the oil pump drive
to modify ignition timing.
Two different proceduresare used for removal
and installation. The first procedure will detail
removal and installation of the sensor only. The sec-
ond procedure will detail removal and installation of
the sensor and oil pump drive shaft assembly. The
second procedure is to be used if the engine has been
disassembled.
An internal oil seal is used in the drive shaft hous-
ing that prevents engine oil at the bottom of the sen-
sor. The seal is not serviceable.
SENSOR ONLY - 4.0L
(1) Disconnect electrical connector at CMP sensor
(Fig. 7).
(2) Remove 2 sensor mounting bolts (Fig. 6) or
(Fig. 7).
(3) Remove sensor from oil pump drive.
OIL PUMP DRIVE AND SENSOR - 4.0L
If the CMP and oil pump drive are to be
removed and installed, do not allow engine
crankshaft or camshaft to rotate. CMP sensor
relationship will be lost.
(1) Disconnect electrical connector at CMP sensor
(Fig. 7).
(2) Remove 2 sensor mounting bolts (Fig. 6) or
(Fig. 7).
(3) Remove sensor from oil pump drive.
(4) Before proceeding to next step, mark and note
rotational position of oil pump drive in relationship
to engine block. After installation, the CMP sensor
should face rear of engine 0É.
(5) Remove hold-down bolt and clamp (Fig. 7).
Fig. 5 CMP Sensor and TonewheelÐ4.7L Engine
1 - NOTCHES
2 - RIGHT CYLINDER HEAD
3 - CAMSHAFT POSITION SENSOR
4 - TONEWHEEL
Fig. 6 CMP and Oil Pump Drive Shaft - 4.0L 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 - 6 IGNITION CONTROLWJ
CAMSHAFT POSITION SENSOR (Continued)

(6) While pulling assembly from engine, note direc-
tion and position of pulse ring (Fig. 6). After removal,
look down into top of oil pump and note direction and
position of slot at top of oil pump gear.
(7) Remove and discard old oil pump drive-to-en-
gine block gasket.
REMOVAL - 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. 10).
It is easier to remove/install sensor from under
vehicle.
(1) Raise and support vehicle.
(2) Disconnect electrical connector at CMP sensor
(Fig. 10).
(3) Remove sensor mounting bolt (Fig. 10).
(4) Carefully pry sensor from cylinder head in a
rocking action with two small screwdrivers.Some
4.7L engines are equipped with a sensor spacer
shim. If equipped, this shim will be located at
sensor bolt hole between cylinder head and
sensor mounting tang (TSB W08±18±00). Save
this shim for sensor installation.
(5) Check condition of sensor o-ring.
Fig. 7 CMP Location - 4.0L Engine
1 - OIL FILTER
2 - CAMSHAFT POSITION SENSOR
3 - CLAMP BOLT
4 - HOLD-DOWN CLAMP
5 - MOUNTING BOLTS (2)
6 - ELEC. CONNECTOR
Fig. 8 CMP Pulse Ring Alignment - 4.0L Engine
1 - PULSE RING (SHUTTER)
2 - TOOTHPICK
3 - SENSOR BASE (OIL PUMP DRIVESHAFT ASSEMBLY)
Fig. 9 Align Timing Marks - 4.0L Engine
1 - CRANKSHAFT VIBRATION DAMPER TIMING MARK
WJIGNITION CONTROL 8I - 7
CAMSHAFT POSITION SENSOR (Continued)

INSTALLATION
INSTALLATION - 4.0L
SENSOR ONLY - 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. 6). The sensor and drive
shaft assembly is located on the right side of the
engine near the oil filter (Fig. 7).
(1) Install sensor to oil pump drive.
(2) Install 2 sensor mounting bolts and tighten to
2 N´m (15 in. lbs.) torque.
(3) Connect electrical connector to CMP sensor.
OIL PUMP DRIVE AND SENSOR - 4.0L
(1) Clean oil pump drive mounting hole area of
engine block.
(2) Install new oil pump drive-to-engine block gas-
ket.
(3) Temporarily install a toothpick or similar tool
through access hole at side of oil pump drive housing.
Align toothpick into mating hole on pulse ring (Fig.
8).(4) Install oil pump drive into engine while align-
ing into slot on oil pump. Rotate oil pump drive back
to its original position and install hold-down clamp
and bolt. Finger tighten bolt. Do not do a final tight-
ening of bolt at this time.
(5) If engine crankshaft or camshaft has been
rotated, such as during engine tear-down, CMP sen-
sor relationship must be reestablished.
(a) Remove ignition coil rail assembly. Refer to
Ignition Coil Removal/Installation.
(b) Remove cylinder number 1 spark plug.
(c) Hold a finger over the open spark plug hole.
Rotate engine at vibration dampener bolt until
compression (pressure) is felt.
(d) Slowly continue to rotate engine. Do this
until timing index mark on vibration damper pul-
ley aligns with top dead center (TDC) mark (0
degree) on timing degree scale (Fig. 9). Always
rotate engine in direction of normal rotation. Do
not rotate engine backward to align timing marks.
(e) Install oil pump drive into engine while
aligning into slot on oil pump. If pump drive will
not drop down flush to engine block, the oil pump
slot is not aligned. Remove oil pump drive and
align slot in oil pump to shaft at bottom of drive.
Install into engine. Rotate oil pump drive back to
its original position and install hold-down clamp
and bolt. Finger tighten bolt. Do not do a final
tightening of bolt at this time.
(f) Remove toothpick from housing.
(6) Install sensor to oil pump drive. After installa-
tion, the CMP sensor should face rear of engine 0É.
(7) Install 2 sensor mounting bolts and tighten to
2 N´m (15 in. lbs.) torque.
(8) Connect electrical connector to CMP sensor.
(9) If removed, install spark plug and ignition coil
rail.
To verify correct rotational position of oil pump
drive, the DRB scan tool must be used.
WARNING: WHEN PERFORMING THE FOLLOWING
TEST, THE ENGINE WILL BE RUNNING. BE CARE-
FUL NOT TO STAND IN LINE WITH THE FAN
BLADES OR FAN BELT. DO NOT WEAR LOOSE
CLOTHING.
(10) Connect DRB scan tool to data link connector.
The data link connector is located in passenger com-
partment, below and to left of steering column.
(11) Gain access to SET SYNC screen on DRB.
(12) Follow directions on DRB screen and start
engine. Bring to operating temperature (engine must
be in ªclosed loopº mode).
(13) With engine running atidle speed, the words
IN RANGE should appear on screen along with 0É.
This indicates correct position of oil pump drive.
Fig. 10 CMP LocationÐ4.7L Engine
1 - RIGHT CYLINDER HEAD
2 - CAMSHAFT POSITION SENSOR
3 - MOUNTING BOLT
4 - ELEC. CONNECTOR
8I - 8 IGNITION CONTROLWJ
CAMSHAFT POSITION SENSOR (Continued)

(14) If a plus (+) or a minus (-) is displayed next to
degree number, and/or the degree displayed is not
zero, loosen but do not remove hold-down clamp bolt.
Rotate oil pump drive until IN RANGE appears on
screen. Continue to rotate oil pump drive until
achieving as close to 0É as possible.
The degree scale on SET SYNC screen of DRB is
referring to fuel synchronization only.It is not
referring to ignition timing.Because of this, do
not attempt to adjust ignition timing using this
method. Rotating oil pump drive will have no effect
on ignition timing. All ignition timing values are con-
trolled by powertrain control module (PCM).
(15) Tighten hold-down clamp bolt to 23 N´m (17
ft. lbs.) torque.
INSTALLATION - 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. 10).
(1) Clean out machined hole in cylinder head.
(2) Apply a small amount of engine oil to sensor
o-ring.
(3) Install sensor into cylinder head 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 head.
If sensor is not flush, damage to sensor mounting
tang may result.
(4) Install mounting bolt and tighten to 12 N´m
(106 in. lbs.) torque.
(5) Connect electrical connector to sensor.
(6) Lower vehicle.
COIL RAIL
DESCRIPTION
A one-piece coil rail assembly containing three
individual coils is used on the 4.0L 6±cylinder engine
(Fig. 11). The coil rail must be replaced as one
assembly. The bottom of the coil is equipped with 6
individual rubber boots (Fig. 11) to seal the 6 spark
plugs to the coil. Inside each rubber boot is a spring.
The spring is used for a mechanical contact between
the coil and the top of the spark plug. These rubber
boots and springs are a permanent part of the coil
and are not serviced separately.
(1) The coil is bolted directly to the cylinder head
(Fig. 12). One electrical connector (located at rear of
coil) is used for all three coils.
Fig. 11 Ignition Coil AssemblyÐ4.0L 6±Cylinder
Engine
1 - CYL. #6
2 - CYL. #5
3 - CYL. #4
4 - CYL. #3
5 - CYL. #2
6 - CYL. #1
7 - COILS (3)
8 - MOUNTING BOLTS (4)
9 - BOLT BASES (4)
10 - RUBBER BOOTS (6)
Fig. 12 Coil LocationÐ4.0L Engine
1 - COIL RAIL
2 - COIL MOUNTING BOLTS (4)
3 - COIL
4 - COIL ELECTRICAL CONNECTION
WJIGNITION CONTROL 8I - 9
CAMSHAFT POSITION SENSOR (Continued)

INSTRUMENT CLUSTER
TABLE OF CONTENTS
page page
INSTRUMENT CLUSTER
DESCRIPTION..........................2
OPERATION............................4
DIAGNOSIS AND TESTING - INSTRUMENT
CLUSTER............................7
REMOVAL.............................9
DISASSEMBLY.........................10
ASSEMBLY............................11
INSTALLATION.........................12
ABS INDICATOR
DESCRIPTION.........................13
OPERATION...........................13
AIRBAG INDICATOR
DESCRIPTION.........................14
OPERATION...........................14
BRAKE/PARK BRAKE INDICATOR
DESCRIPTION.........................15
OPERATION...........................15
DIAGNOSIS AND TESTING - BRAKE
INDICATOR..........................16
CHECK GAUGES INDICATOR
DESCRIPTION.........................16
OPERATION...........................17
COOLANT LOW INDICATOR
DESCRIPTION.........................17
OPERATION...........................18
CRUISE INDICATOR
DESCRIPTION.........................18
OPERATION...........................18
ENGINE TEMPERATURE GAUGE
DESCRIPTION.........................19
OPERATION...........................19
FRONT FOG LAMP INDICATOR
DESCRIPTION.........................20
OPERATION...........................20
FUEL GAUGE
DESCRIPTION.........................21
OPERATION...........................21
HIGH BEAM INDICATOR
DESCRIPTION.........................22
OPERATION...........................22
LOW FUEL INDICATOR
DESCRIPTION.........................22
OPERATION...........................23
MALFUNCTION INDICATOR LAMP (MIL)
DESCRIPTION.........................23OPERATION...........................23
ODOMETER
DESCRIPTION.........................24
OPERATION...........................25
OIL PRESSURE GAUGE
DESCRIPTION.........................25
OPERATION...........................26
OVERDRIVE OFF INDICATOR
DESCRIPTION.........................26
OPERATION...........................26
REAR FOG LAMP INDICATOR
DESCRIPTION.........................27
OPERATION...........................27
SEATBELT INDICATOR
DESCRIPTION.........................28
OPERATION...........................28
SHIFT INDICATOR (TRANSFER CASE)
DESCRIPTION.........................29
OPERATION...........................29
SKIS INDICATOR
DESCRIPTION.........................29
OPERATION...........................29
SPEEDOMETER
DESCRIPTION.........................30
OPERATION...........................31
TACHOMETER
DESCRIPTION.........................31
OPERATION...........................31
TRANS TEMP INDICATOR
DESCRIPTION.........................32
OPERATION...........................32
TURN SIGNAL INDICATOR
DESCRIPTION.........................33
OPERATION...........................33
DIAGNOSIS AND TESTING - TURN SIGNAL
INDICATOR..........................33
VOLTAGE GAUGE
DESCRIPTION.........................34
OPERATION...........................34
WAIT-TO-START INDICATOR
DESCRIPTION.........................35
OPERATION...........................35
WATER-IN-FUEL INDICATOR
DESCRIPTION.........................36
OPERATION...........................36
WJINSTRUMENT CLUSTER 8J - 1

INSTRUMENT CLUSTER
DESCRIPTION
The instrument cluster for this model is an Elec-
troMechanical Instrument Cluster (EMIC) module
that is located in the instrument panel above the
steering column opening, directly in front of the
driver (Fig. 1). The remainder of the EMIC, including
the mounts and the electrical connections, are con-
cealed behind the cluster bezel. The EMIC gauges
and indicators are protected by an integral clear
plastic cluster lens, and are visible through a dedi-
cated hooded opening in the instrument panel top
pad. Just behind and integral to the cluster lens are
the cluster hood and cluster mask, which are con-
structed of molded black plastic. Two cluster masks
are used: A base version features a black matte face
and no trim ring around the perimeter of each gauge
opening, while a premium version features a black
matte face and a raised trim ring around the perim-
eter of each gauge opening. The cluster hood serves
as a visor and shields the face of the cluster from
ambient light and reflections to reduce glare, while
the cluster mask serves to separate and define the
individual gauges of the EMIC. On the lower edge of
the cluster lens just right of the speedometer, the
black plastic odometer/trip odometer switch button
protrudes through dedicated holes in the cluster
mask and the cluster lens. The molded plastic EMIC
lens, hood and mask unit has four integral mounting
tabs, two tabs extend down vertically from the lower
edge of the unit and two tabs extend horizontally
rearward from the upper surface of the hood. The
two lower mounting tabs are used to secure theEMIC to the molded plastic instrument panel cluster
carrier with two screws, while the two upper tabs are
secured to the underside of the hood formation of the
instrument panel top pad with two screws. A single
molded connector receptacle located on the EMIC
electronic circuit board is accessed from the back of
the cluster housing and is connected to the vehicle
electrical system through a single dedicated take out
and connector of the instrument panel wire harness.
The cluster mask features two large round open-
ings near its center through which the two major
gauges are visible, and two smaller round openings
stacked at the outboard side of each of the large
openings through which the four minor gauges are
visible. The cluster mask and the dial faces of the
gauges are laminated plastic units. The dark, visible
surface of the mask and the gauge dial faces are the
outer layer or overlay, which is translucent. The
darkness of this outer layer prevents the cluster from
appearing too cluttered or busy by concealing the
cluster indicators that are not illuminated, while the
translucence of this layer allows those indicators and
icons that are illuminated to be readily visible. The
underlying layer of the cluster mask overlay is
opaque and allows light from the various indicators
behind it to be visible through the outer layer of the
mask and gauge dial faces only through predeter-
mined cutouts. On the base instrument clusters the
graphics, increments, and numerals on the gauge
faces are also translucent and illuminated from
behind, while the orange gauge pointers are illumi-
nated internally. On the premium instrument clus-
ters the graphics, increments, numerals and gauge
needles are opaque while the remainder of the gauge
faces are translucent and illuminated from behind by
an electro-luminescent lamp. The EMIC electronic
circuitry is protected by a molded plastic rear cover
that features several round access holes for service of
the incandescent cluster indicator and illumination
lighting lamps and a large rectangular access hole
for the EMIC connector receptacle. The EMIC rear
cover is secured to the cluster housing with screws,
while the cluster lens, hood, and mask unit is
secured to the cluster housing with several integral
plastic latch features.
Twelve versions of the EMIC module are offered on
this model, two base and ten premium. These ver-
sions accommodate all of the variations of optional
equipment and regulatory requirements for the vari-
ous markets in which the vehicle will be offered. This
module utilizes integrated circuitry and information
carried on the Programmable Communications Inter-
face (PCI) data bus network for control of all gauges
and many of the indicators. (Refer to 8 - ELECTRI-
CAL/ELECTRONIC CONTROL MODULES/COM-
MUNICATION - DESCRIPTION - PCI BUS). The
Fig. 1 Instrument Cluster
1 - INSTRUMENT PANEL TOP PAD HOOD FORMATION
2 - INSTRUMENT CLUSTER
3 - CLUSTER BEZEL
8J - 2 INSTRUMENT CLUSTERWJ