2003 JEEP GRAND CHEROKEE fuse diagram

DESCRIPTION - CIRCUIT FUNCTIONS
All circuits in the diagrams use an alpha/numeric
code to identify the wire and it's function. To identify
which circuit code applies to a system, refer to the
Circuit Identification Code Chart. This chart shows
the main circuits only and does not show the second-
ary codes that may apply to some models.
CIRCUIT IDENTIFICATION CODE CHART
CIRCUIT FUNCTION
A BATTERY FEED
B BRAKE CONTROLS
C CLIMATE CONTROLS
D DIAGNOSTIC CIRCUITS
E DIMMING ILLUMINATION
CIRCUITS
F FUSED CIRCUITS
G MONITORING CIRCUITS
(GAUGES)
H OPEN
I NOT USED
J OPEN
K POWERTRAIN CONTROL
MODULE
L EXTERIOR LIGHTING
M INTERIOR LIGHTING
N NOT USED
O NOT USED
P POWER OPTION (BATTERY
FEED)
Q POWER OPTIONS (IGNITION
FEED)
R PASSIVE RESTRAINT
S SUSPENSION/STEERING
T TRANSMISSION/TRANSAXLE/
TRANSFER CASE
U OPEN
V SPEED CONTROL, WIPER/
WASHER
W OPEN
X AUDIO SYSTEMS
Y OPEN
Z GROUNDS
DESCRIPTION - SECTION IDENTIFICATION AND
INFORMATION
The wiring diagrams are grouped into individual
sections. If a component is most likely found in a par-
ticular group, it will be shown complete (all wires,
connectors, and pins) within that group. For exam-
ple, the Auto Shutdown Relay is most likely to be
found in Group 30, so it is shown there complete. It
can, however, be shown partially in another group if
it contains some associated wiring.
Splice diagrams in Section 8W-70 show the entire
splice and provide references to other sections the
splices serves. Section 8W-70 only contains splice dia-
grams that are not shown in their entirety some-
where else in the wiring diagrams.
Section 8W-80 shows each connector and the cir-
cuits involved with that connector. The connectors
are identified using the name/number on the dia-
gram pages.
WIRING SECTION CHART
GROUP TOPIC
8W-01 thru
8W-09General information and Diagram
Overview
8W-10 thru
8W-19Main Sources of Power and
Vehicle Grounding
8W-20 thru
8W-29Starting and Charging
8W-30 thru
8W-39Powertrain/Drivetrain Systems
8W-40 thru
8W-49Body Electrical items and A/C
8W-50 thru
8W-59Exterior Lighting, Wipers and
Trailer Tow
8W-60 thru
8W-69Power Accessories
8W-70 Splice Information
8W-80 Connector Pin Outs
8W-91 Connector, Ground and Splice
Locations
8W - 01 - 6 8W-01 WIRING DIAGRAM INFORMATIONWJ
WIRING DIAGRAM INFORMATION (Continued)

STANDARD PROCEDURE - TESTING OF
VOLTAGE POTENTIAL
(1) Connect the ground lead of a voltmeter to a
known good ground (Fig. 7).
(2) Connect the other lead of the voltmeter to the
selected test point. The vehicle ignition may need to
be turned ON to check voltage. Refer to the appropri-
ate test procedure.
STANDARD PROCEDURE - TESTING FOR
CONTINUITY
(1) Remove the fuse for the circuit being checked
or, disconnect the battery.
(2) Connect one lead of the ohmmeter to one side
of the circuit being tested (Fig. 8).
(3) Connect the other lead to the other end of the
circuit being tested. Low or no resistance means good
continuity.
STANDARD PROCEDURE - TESTING FOR A
SHORT TO GROUND
(1) Remove the fuse and disconnect all items
involved with the fuse.
(2) Connect a test light or a voltmeter across the
terminals of the fuse.
(3) Starting at the fuse block, wiggle the wiring
harness about six to eight inches apart and watch
the voltmeter/test lamp.
(4) If the voltmeter registers voltage or the test
lamp glows, there is a short to ground in that gen-
eral area of the wiring harness.
Fig. 7 TESTING FOR VOLTAGE POTENTIAL
Fig. 8 TESTING FOR CONTINUITY
1 - FUSE REMOVED FROM CIRCUIT
WJ8W-01 WIRING DIAGRAM INFORMATION 8W - 01 - 9
WIRING DIAGRAM INFORMATION (Continued)

STANDARD PROCEDURE - TESTING FOR A
SHORT TO GROUND ON FUSES POWERING
SEVERAL LOADS
(1) Refer to the wiring diagrams and disconnect or
isolate all items on the suspected fused circuits.
(2) Replace the blown fuse.
(3) Supply power to the fuse by turning ON the
ignition switch or re-connecting the battery.
(4) Start connecting or energizing the items in the
fuse circuit one at a time. When the fuse blows the
circuit with the short to ground has been isolated.
STANDARD PROCEDURE - TESTING FOR A
VOLTAGE DROP
(1) Connect the positive lead of the voltmeter to
the side of the circuit closest to the battery (Fig. 9).
(2) Connect the other lead of the voltmeter to the
other side of the switch, component or circuit.
(3) Operate the item.
(4) The voltmeter will show the difference in volt-
age between the two points.
SPECIAL TOOLS
WIRING/TERMINAL
Fig. 9 TESTING FOR VOLTAGE DROP
PROBING TOOL PACKAGE 6807
TERMINAL PICK TOOL SET 6680
TERMINAL REMOVING TOOLS 6932 AND 8638
TERMINAL REMOVING TOOL 6934
8W - 01 - 10 8W-01 WIRING DIAGRAM INFORMATIONWJ
WIRING DIAGRAM INFORMATION (Continued)

8W-97 POWER DISTRIBUTION
TABLE OF CONTENTS
page page
POWER DISTRIBUTION
DESCRIPTION..........................1
OPERATION............................1
SPECIAL TOOLS
POWER DISTRIBUTION SYSTEMS.........2
CIGAR LIGHTER OUTLET
DESCRIPTION..........................2
OPERATION............................2
DIAGNOSIS AND TESTING - CIGAR LIGHTER
OUTLET.............................2
CIGAR LIGHTER OUTLET DOOR SPRING
REMOVAL.............................3
INSTALLATION..........................3
IOD FUSE
DESCRIPTION..........................3
OPERATION............................4
REMOVAL.............................4
INSTALLATION..........................4
JUNCTION BLOCK
DESCRIPTION..........................5
OPERATION............................5
REMOVAL.............................5
INSTALLATION..........................6
POWER DISTRIBUTION CENTER
DESCRIPTION..........................7
OPERATION............................8
REMOVAL.............................8
DISASSEMBLY
POWER DISTRIBUTION CENTER
DISASSEMBLY........................9ASSEMBLY
POWER DISTRIBUTION CENTER
ASSEMBLY..........................11
INSTALLATION.........................12
POWER OUTLET
DESCRIPTION - FRONT POWER OUTLET....12
OPERATION - FRONT POWER OUTLET......12
DIAGNOSIS AND TESTING - POWER OUTLET . 12
REMOVAL.............................13
INSTALLATION.........................13
POWER OUTLET RELAY
DESCRIPTION.........................13
OPERATION...........................14
DIAGNOSIS AND TESTING - POWER OUTLET
RELAY..............................14
REMOVAL.............................15
INSTALLATION.........................15
IOD WIRE HARNESS CONNECTOR
DESCRIPTION.........................15
OPERATION...........................15
FUSE COVER
REMOVAL.............................16
INSTALLATION.........................16
REAR POWER OUTLET
DESCRIPTION - REAR POWER OUTLET.....16
OPERATION - REAR POWER OUTLET.......17
DIAGNOSIS AND TESTING - REAR POWER
OUTLET............................17
REMOVAL.............................17
INSTALLATION.........................18
POWER DISTRIBUTION
DESCRIPTION
This group covers the various standard and
optional power distribution components used on this
model. The power distribution system for this vehicle
consists of the following components:
²Power Distribution Center (PDC)
²Junction Block (JB)
²Power Outlets
The power distribution system also incorporates
various types of circuit control and protection fea-
tures, including:
²Automatic resetting circuit breakers
²Blade-type fuses
²Bus bars
²Cartridge fuses²Circuit splice blocks
²Flashers
²Fusible links
²Standard and Micro-Relays
Following are general descriptions of the major
components in the power distribution system. See the
owner's manual in the vehicle glove box for more
information on the features and use of all of the
power distribution system components. Refer to Wir-
ing Diagrams for complete circuit diagrams.
OPERATION
The power distribution system for this vehicle is
designed to provide safe, reliable, and centralized dis-
tribution points for the electrical current required to
operate all of the standard and optional factory-in-
stalled electrical and electronic powertrain, chassis,
safety, security, comfort and convenience systems. At
WJ8W-97 POWER DISTRIBUTION 8W - 97 - 1

the same time, the power distribution system was
designed to provide ready access to these electrical
distribution points for the vehicle technician to use
when conducting diagnosis and repair of faulty cir-
cuits. The power distribution system can also prove
useful for the sourcing of additional electrical circuits
that may be required to provide the electrical current
needed to operate accessories that the vehicle owner
may choose to have installed in the aftermarket.
NOTE: DO NOT ATTEMPT TO SWAP POWER DIS-
TRIBUTION CENTERS FROM ONE VEHICLE TO
ANOTHER. MOST OF THESE ASSEMBLIES ARE
VEHICLE FEATURE SPECIFIC AND THEREFORE
NOT INTERCHANGEABLE. ALWAYS USE THE COR-
RECT PART NUMBERED ASSEMBLY WHEN DIAG-
NOSING OR REPLACING A POWER DISTRIBUTION
CENTER.
SPECIAL TOOLS
POWER DISTRIBUTION SYSTEMS
CIGAR LIGHTER OUTLET
DESCRIPTION
A cigar lighter outlet is standard equipment on
this model. On models equipped with the optional
Smoker's Package, the cigar lighter knob and heating
element are included. On models without the Smok-
er's Package, the cigar lighter outlet is equipped with
a snap fit plastic cap and is treated as an extra
accessory power outlet. The cigar lighter outlet is
installed in the instrument panel center lower bezel,
which is located near the bottom of the instrument
panel center stack area, below the heater and air
conditioner controls. The cigar lighter outlet is
secured by a snap fit within the center lower bezel.The cigar lighter outlet, plastic cap and the knob
and heating element unit are available for service
replacement. These components cannot be repaired
and, if faulty or damaged, they must be replaced.
OPERATION
The cigar lighter consists of two major components:
a knob and heating element unit, and the cigar
lighter base or outlet shell. The receptacle shell is
connected to ground, and an insulated contact in the
bottom of the shell is connected to battery current.
The cigar lighter receives battery voltage from a fuse
in the junction block when the ignition switch is in
the Accessory or On positions.
The cigar lighter knob and heating element are
encased within a spring-loaded housing, which also
features a sliding protective heat shield. When the
knob and heating element are inserted in the outlet
shell, the heating element resistor coil is grounded
through its housing to the outlet shell. If the cigar
lighter knob is pushed inward, the heat shield slides
up toward the knob exposing the heating element,
and the heating element extends from the housing
toward the insulated contact in the bottom of the
outlet shell.
Two small spring-clip retainers are located on
either side of the insulated contact inside the bottom
of the outlet shell. These clips engage and hold the
heating element against the insulated contact long
enough for the resistor coil to heat up. When the
heating element is engaged with the contact, battery
current can flow through the resistor coil to ground,
causing the resistor coil to heat.
When the resistor coil becomes sufficiently heated,
excess heat radiates from the heating element caus-
ing the spring-clips to expand. Once the spring-clips
expand far enough to release the heating element,
the spring-loaded housing forces the knob and heat-
ing element to pop back outward to their relaxed
position. When the cigar lighter knob and element
are pulled out of the outlet shell, the protective heat
shield slides downward on the housing so that the
heating element is recessed and shielded around its
circumference for safety.
DIAGNOSIS AND TESTING - CIGAR LIGHTER
OUTLET
For complete circuit diagrams, refer toHorn/Ci-
gar Lighter/Power Outletin Wiring Diagrams.
(1) Check the fused B(+) fuse in the junction block.
If OK, go to Step 2. If not OK, repair the shorted cir-
cuit or component as required and replace the faulty
fuse.
(2) Turn the ignition switch to the On position.
Check for battery voltage at the fused B(+) fuse in
Terminal Pick Kit 6680
8W - 97 - 2 8W-97 POWER DISTRIBUTIONWJ
POWER DISTRIBUTION (Continued)

JUNCTION BLOCK
DESCRIPTION
An electrical Junction Block (JB) is concealed
beneath the driver side of the instrument panel in
the passenger compartment of the vehicle (Fig. 3).
The JB combines the functions previously provided
by a separate fuseblock module and relay center. The
JB serves to simplify and centralize numerous elec-
trical components, as well as to distribute electrical
current to many of the accessory systems in the vehi-
cle. It also eliminates the need for numerous splice
connections. The JB houses up to thirty-three blade-
type mini fuses, up to two blade-type automatic
resetting circuit breakers, the electronic combination
flasher, the Daytime Running Lamp (DRL) module
(Canada only) and up to twelve International Stan-
dards Organization (ISO) relays (three standard-type
and nine micro-type). The JB also incorporates an
integral connector and mounting for the Body Con-
trol Module (BCM). The BCM is secured with four
screws directly to the dash panel side of the JB.
Refer toBody Control Modulein Electronic Con-
trol Modules for additional information covering the
BCM.
The molded plastic JB housing has integral mounts
that are secured with two screws and two snap
retainers to the instrument panel steering column
support bracket behind the instrument panel steer-ing column opening cover. The JB is concealed above
the molded plastic instrument panel fuse cover. Inte-
gral latches molded into the fuse cover secure it the
JB, the BCM and the 16-way data link connector tab
of the instrument panel steering column support
bracket. The fuse cover can be pulled downward to
disengage the latches and provide service access to
all of the fuses, relays and wire harness connectors of
the JB. The fuse cover has a fuse puller and spare
fuses secured to its upper surface. Refer toInstru-
ment Panel Fuse Coverin Body for additional ser-
vice information.
The JB unit cannot be repaired and is only ser-
viced as an assembly. If any internal circuit or the JB
housing is faulty or damaged, the entire JB unit
must be replaced. The BCM is available for separate
service replacement.
OPERATION
All of the circuits entering and leaving the Junc-
tion Block (JB) do so through up to five wire harness
connectors, which are connected to the JB through
integral connector receptacles molded into the JB
housing. Internal connection of all of the JB circuits
is accomplished by a printed circuit board. There are
also two separate wire harness connections to con-
nector receptacles that are integral to the BCM.
Refer toJunction Blockin Wiring Diagrams for
additional information and the location of complete
JB circuit diagrams.
REMOVAL
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. DISCON-
NECT AND ISOLATE THE BATTERY NEGATIVE
(GROUND) CABLE, THEN WAIT TWO MINUTES FOR
THE AIRBAG SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE AIRBAG SYSTEM. FAILURE TO TAKE
THE PROPER PRECAUTIONS COULD RESULT IN
ACCIDENTAL AIRBAG DEPLOYMENT AND POSSI-
BLE PERSONAL INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the fuse cover from the bottom of the
Junction Block (JB).
(3) Remove the steering column opening cover
from the instrument panel. Refer toSteering Col-
umn Opening Coverin Body for the location of
steering column opening cover removal procedures.
Fig. 3 Junction Block Location
1 - REAR LATCHES
2 - JUNCTION BLOCK AND BODY CONTROL MODULE UNIT
3 - INSTRUMENT PANEL FUSE COVER
4 - SIDE LATCH
5 - FRONT LATCHES
WJ8W-97 POWER DISTRIBUTION 8W - 97 - 5

(4) Reach behind the JB to disconnect the two
instrument panel wire harness connectors from the
Body Control Module (BCM) connector receptacles
located near the bottom of the JB (Fig. 4).
(5) Reach behind the JB to remove the screw that
secures the instrument panel wire harness bulkhead
connector to the connector receptacle located near the
top of the JB and disconnect the connector.
(6) Disconnect the fused B(+) and the IOD wire
harness connectors from the connector receptacles
located near the bottom of the JB (Fig. 5).
(7) Remove the screws that secure the right and
left body wire harness bulkhead connectors to the
connector receptacles located near the center of the
JB and disconnect the connectors.
(8) Remove the two screws that secure the JB to
the instrument panel steering column support
bracket (Fig. 6).
(9) To disengage the two snap clips that secure the
top of the JB to the instrument panel steering col-
umn support bracket, grasp the bottom of the junc-
tion block firmly with both hands and pull it
downward sharply.
(10) Remove the JB from the instrument panel
steering column support bracket.
INSTALLATION
NOTE: If the Junction Block (JB) is being replaced
with a new unit, be certain to transfer each of the
optional fuses, circuit breakers and relays from thefaulty JB to the proper cavities of the replacement
JB. Refer to Junction Block in Wiring Diagrams for
the location of complete circuit diagrams and cavity
assignments for the JB. The Body Control Module
(BCM) must also be transferred to the new JB.
Refer to Body Control Module in Electronic Control
Modules for the location of the BCM removal and
installation procedures.
(1)
Position the JB into its mounting location on the
instrument panel steering column support bracket.
(2) Align the snap clips at the top of the JB with
the mounting holes in the instrument panel steering
column support bracket.
(3) Grasp the bottom of the JB firmly with both
hands and push it upward sharply to engage the two
snap clips that secure the top of the JB to the instru-
ment panel steering column support bracket.
(4)
Install and tighten the two screws that secure the
JB to the instrument panel steering column support
bracket. Tighten the screws to 2.2 N´m (20 in. lbs.).
Fig. 4 Junction Block Connections
1 - SCREW
2 - JUNCTION BLOCK
3 - BULKHEAD CONNECTOR
4 - BODY CONTROL MODULE
5 - INSTRUMENT PANEL WIRE HARNESS CONNECTORS
Fig. 5 Junction Block Connections
1 - SNAP CLIPS
2 - SCREW
3 - CONNECTOR
4 - LEFT BODY WIRE HARNESS
5 - IOD CONNECTOR
6 - FUSED B+ CONNECTOR
7 - RIGHT BODY WIRE HARNESS
8 - SCREW
9 - CONNECTOR
10 - JUNCTION BLOCK
8W - 97 - 6 8W-97 POWER DISTRIBUTIONWJ
JUNCTION BLOCK (Continued)

are only serviced as a unit with the right headlamp
and dash wire harness. If the PDC main housing
unit, fuse wedges or the bus bars are faulty or dam-
aged, the right headlamp and dash wire harness unit
must be replaced.
OPERATION
All of the current from the battery and the generator
output enters the PDC through two cables and a single
two-holed eyelet that is secured with nuts to the two
PDC B(+) terminal studs just inside the front end of the
PDC housing. The PDC cover is unlatched and opened
to access the battery and generator output connection
B(+) terminal studs, the fuses or the relays. Internal
connection of all of the PDC circuits is accomplished by
an intricate combination of hard wiring and bus bars.
Refer toPower Distribution
in Wiring Diagrams for
the location of complete PDC circuit diagrams.
REMOVAL
The Power Distribution Center (PDC) main housing
unit, the PDC fuse wedges and the PDC bus bars can-
not be repaired and are only serviced as a unit with the
right headlamp and dash wire harness. If the PDC
main housing unit, the fuse wedges or the bus bars are
faulty or damaged, the entire PDC and right headlamp
and dash wire harness unit must be replaced.
(1)Disconnect and isolate the battery negative cable.
(2) Disconnect each of the right headlamp and
dash wire harness connectors. Refer toConnector
Locationsin Wiring Diagrams for the location of
more information on the right headlamp and dash
wire harness connector locations.
(3) Remove all of the fasteners that secure each of
the right headlamp and dash wire harness ground
eyelets to the vehicle body and chassis components.
Refer toConnector Locationsin Wiring Diagrams
for the location of more information on the ground
eyelet locations.
(4) Disengage each of the retainers that secure the
right headlamp and dash wire harness to the vehicle
body and chassis components. Refer toConnector
Locationsin Wiring Diagrams for the location of
more information on the right headlamp and dash
wire harness retainer locations.
(5) Unlatch and open the PDC cover.
(6) Remove the two nuts that secure the two-holed
eyelet of the battery wire harness PDC take outs to
the PDC B(+) terminal studs (Fig. 8).
(7) Remove the battery wire harness PDC take out
eyelet from the B(+) terminal studs.
(8) Disengage the latches on the PDC housing
mounts from the tabs on the PDC mounting stan-
chions of the battery support, and pull the PDC
housing upward to disengage the mounts from the
stanchions (Fig. 9).
Fig. 8 Power Distribution Center Connections
1 - PDC COVER
2 - NUT (2)
3 - EYELET
4 - B(+) TERMINAL STUDS
Fig. 9 Power Distribution Center Remove/Install
1 - POWER DISTRIBUTION CENTER
2 - MOUNTS
3 - STANCHIONS (3)
4 - BATTERY SUPPORT
8W - 97 - 8 8W-97 POWER DISTRIBUTIONWJ
POWER DISTRIBUTION CENTER (Continued)