exj 8o, JEEP Manuals, Electronic Service Manual (jeep cherokee xj do 2000)
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XJ
POWER DISTRIBUTION SYSTEMS
8O - 1
POWER DISTRIBUTION SYSTEMS
TABLE OF CONTENTS
page
page
DESCRIPTION AND OPERATION
REMOVAL AND INSTALLATION
DISASSEMBLY AND ASSEMBLY
SPECIAL TOOLS
DESCRIPTION AND OPERATION
NOTE: This group covers both Left-Hand Drive
(LHD) and Right-Hand Drive (RHD) versions of this
model. Whenever required and feasible, the RHD
versions of affected vehicle components have been
constructed as mirror-image of the LHD versions.
While most of the illustrations used in this group
represent only the LHD version, the diagnostic and
service procedures outlined can generally be
applied to either version. Exceptions to this rule
have been clearly identified as LHD or RHD, if a
special illustration or procedure is required.
POWER DISTRIBUTION SYSTEM
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:
²
Power Distribution Center (PDC)
Junction Block (JB).
The power distribution system also incorporates
various types of circuit control and protection fea-
tures, including:
²
²
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 many standard and optional facto-
ry-installed electrical and electronic powertrain,
chassis, safety, security, comfort and convenience sys-
tems. At the same time, the power distribution sys-
tem was designed to provide ready access to these
electrical distribution points for the vehicle techni-
cian to use when conducting diagnosis and repair of
faulty circuits. The power distribution system can
also prove useful for the sourcing of additional elec-
trical circuits that may be required to provide the
electrical current needed to operate many accessories
that the vehicle owner may choose to have installed
in the aftermarket.
Automatic resetting circuit breakers
²
Blade-type fuses
²
Maxi fuse-type fusible links
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 the
index in this service manual for the location of com-
plete circuit diagrams for the various power distribu-
tion system components.
²
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POWER DISTRIBUTION SYSTEMS
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DESCRIPTION AND OPERATION (Continued)
POWER DISTRIBUTION CENTER
replacement. The PDC main housing unit, the fuse
wedges, the fuse cassette and the bus bars cannot be
repaired and are only serviced as a unit with the
headlamp and dash wire harness. If the PDC main
housing unit, fuse wedges, fuse cassette or the bus
bars are faulty or damaged, the headlamp and dash
wire harness unit must be replaced.
DESCRIPTION
OPERATION
All of the current from the battery and the gener-
ator output enters the PDC through two cables and
eyelets that are secured with a nut to the PDC B(+)
terminal stud located on one end of the PDC housing.
The PDC B(+) terminal stud cover is unlatched and
removed to access the battery and generator output
connection B(+) terminal stud. The PDC cover is
unlatched and opened or removed to access the fuses
or relays. Internal connection of all of the PDC cir-
cuits is accomplished by an intricate combination of
hard wiring and bus bars. Refer to
Power Distribu-
tion
in the index of this service manual for the loca-
tion of complete PDC circuit diagrams.
Fig. 1 Power Distribution Center Location
1 – LEFT FENDER
2 – BATTERY
3 – POWER DISTRIBUTION CENTER
IGNITION-OFF DRAW FUSE
DESCRIPTION
All of the electrical current distributed throughout
this vehicle is directed through the standard equip-
ment Power Distribution Center (PDC) (Fig. 1). The
molded plastic PDC housing is located on the right
side of the engine compartment, just behind the bat-
tery. The PDC houses up to fourteen blade-type maxi
fuses, which replace all in-line fusible links. The PDC
also houses up to twelve blade-type mini fuses, and
up to eight International Standards Organization
(ISO) relays (four standard-type and four micro-type).
The PDC housing is secured to a stamped sheet
metal bracket in the engine compartment by mount-
ing slots and tabs that are integral to the PDC hous-
ing. The PDC mounting bracket is secured with two
screws to the right front inner fender shield above
the right front wheel house. The PDC housing has a
molded plastic cover that includes two integral hinge
tabs on the inboard side, and an integral latch on the
outboard side. The PDC cover is easily opened or
removed for service access and has a convenient fuse
and relay layout map integral to the inside surface of
the cover to ensure proper component identification.
A separate molded plastic B(+) terminal stud cover is
secured by two integral tabs and a latch to one end
of the PDC housing.
The PDC cover, the PDC housing lower cover, the
PDC B(+) terminal stud cover, the PDC relay wedges
and the PDC relay cassettes are available for service
Fig. 2 Ignition-Off Draw Fuse
1 – POWER DISTRIBUTION CENTER
2 – IGNITION-OFF DRAW FUSE
All vehicles are equipped with an Ignition-Off
Draw (IOD) fuse (Fig. 2) that is removed from its
cavity in the Power Distribution Center (PDC) when
the vehicle is shipped from the factory. Dealer per-
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POWER DISTRIBUTION SYSTEMS
8O - 3
DESCRIPTION AND OPERATION (Continued)
sonnel are to remove the IOD fuse from the storage
location and install it into PDC fuse cavity 16 as part
of the preparation procedures performed just prior to
new vehicle delivery.
The PDC has a molded plastic cover that can be
removed to provide service access to all of the fuses
and relays in the PDC. An integral latch and hinge
tabs are molded into the PDC cover for easy removal.
A fuse layout map is integral to the underside of the
PDC cover to ensure proper fuse and relay identifica-
tion. The IOD fuse is a 15 ampere mini blade-type
fuse and, when removed, it is stored in a plastic fuse
holder formation that is molded into the underside of
the PDC cover.
Battery
in the index of this service manual for the
location
of
additional
service
information
covering
the battery.
JUNCTION BLOCK
DESCRIPTION
OPERATION
The term ignition-off draw identifies a normal con-
dition where power is being drained from the battery
with the ignition switch in the Off position. The IOD
fuse feeds the memory and sleep mode functions for
many of the electronic modules in the vehicle as well
as various other accessories that require battery cur-
rent when the ignition switch is in the Off position,
including the clock. The only reason the IOD fuse is
removed is to reduce the normal IOD of the vehicle
electrical system during new vehicle transportation
and pre-delivery storage to reduce battery depletion,
while still allowing vehicle operation so that the
vehicle can be loaded, unloaded and moved as needed
by both vehicle transportation company and dealer
personnel.
The IOD fuse is removed from PDC fuse cavity 16
when the vehicle is shipped from the assembly plant.
Dealer personnel must install the IOD fuse when the
vehicle is being prepared for delivery in order to
restore full electrical system operation. Once the
vehicle is prepared for delivery, the IOD function of
this fuse becomes transparent and the fuse that has
been assigned the IOD designation becomes only
another Fused B(+) circuit fuse. The IOD fuse serves
no useful purpose to the dealer technician in the ser-
vice or diagnosis of any vehicle system or condition,
other than the same purpose as that of any other
standard circuit protection device.
The IOD fuse can be used by the vehicle owner as
a convenient means of reducing battery depletion
when a vehicle is to be stored for periods not to
exceed about thirty days. However, it must be
remembered that removing the IOD fuse will not
eliminate IOD, but only reduce this normal condition.
If a vehicle will be stored for more than about thirty
days, the battery negative cable should be discon-
nected to eliminate normal IOD; and, the battery
should be tested and recharged at regular intervals
during the vehicle storage period to prevent the bat-
tery from becoming discharged or damaged. Refer to
Fig. 3 Junction Block Location
1 – JUNCTION BLOCK
2 – FUSE ACCESS PANEL
3 – RIGHT COWL SIDE INNER TRIM PANEL
An electrical Junction Block (JB) is concealed
behind the right cowl side inner trim 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 electrical
components, as well as to distribute electrical current
to many of the accessory systems in the vehicle. It
also eliminates the need for numerous splice connec-
tions and serves in place of a bulkhead connector
between many of the engine compartment, instru-
ment panel, and body wire harnesses. The JB houses
up to twenty-seven blade-type fuses (three standard-
type and twenty-four mini-type), up to three blade-
type automatic resetting circuit breakers, and four
International
Standards
Organization
(ISO)
relays
(three standard-type and one micro-type).
The molded plastic JB housing has integral mount-
ing brackets that are secured with three nuts to
studs on the right cowl side inner panel below the
instrument panel. The right cowl side inner trim
panel is secured to a stud on the JB with a push nut.
A snap-fit fuse access panel can be removed for ser-
vice of the JB fuses and also conceals the push nut. A
finger recess is molded into the front of the fuse
 8O - 4
POWER DISTRIBUTION SYSTEMS
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DESCRIPTION AND OPERATION (Continued)
access panel for easy removal, and a fuse puller and
spare fuse holders are located on the back of the fuse
access panel.
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.
OPERATION
All of the circuits entering and leaving the JB do
so through up to ten wire harness connectors, which
are connected to the JB through integral connector
receptacles molded into the JB housing. Internal con-
nection of all of the JB circuits is accomplished by an
intricate combination of hard wiring and bus bars.
Refer to
Junction Block
in the index of this service
manual for the location of complete JB circuit dia-
grams.
Fig. 4 Power Distribution Center Connections
1 – COVER
2 – NUT
3 – POWER DISTRIBUTION CENTER
4 – BATTERY
5 – BATTERY WIRE HARNESS PDC TAKE-OUTS
REMOVAL AND INSTALLATION
POWER DISTRIBUTION CENTER
The Power Distribution Center (PDC) main hous-
ing unit, the PDC fuse wedges, the PDC fuse cassette
and the PDC bus bars cannot be repaired and are
only serviced as a unit with the headlamp and dash
wire harness. If the PDC main housing unit, the fuse
wedge, the fuse cassette or the bus bars are faulty or
damaged, the entire PDC and headlamp and dash
wire harness unit must be replaced.
(7) Remove the battery wire harness PDC take out
eyelets from the B(+) terminal stud.
(8) Disengage the latches on the PDC mounting
bracket from the tabs on the PDC housing, and pull
the PDC housing upward to disengage the mounting
slots from the stanchions of the mounting bracket
(Fig. 5).
(9) Remove the PDC and the headlamp and dash
wire harness from the engine compartment as a unit.
(10) Remove the two screws that secure the PDC
mounting bracket to the right front inner fender (Fig.
6).
(11) Remove the PDC mounting bracket from the
right front inner fender.
REMOVAL
(1) Disconnect
and
isolate
the
battery
negative
cable.
(2) Disconnect each of the headlamp and dash wire
harness connectors. Refer to
Connector Locations
in the index of this service manual for the location of
more information on the headlamp and dash wire
harness connector locations.
(3) Remove all of the fasteners that secure each of
the headlamp and dash wire harness ground eyelets
to the vehicle body and chassis components. Refer to
Connector Locations
in the index of this service
manual for the location of more information on the
ground eyelet locations.
(4) Disengage each of the retainers that secure the
headlamp and dash wire harness to the vehicle body
and chassis components. Refer to
Connector Loca-
tions
in the index of this service manual for the loca-
tion of more information on the headlamp and dash
wire harness retainer locations.
(5) Unlatch
INSTALLATION
NOTE: If the PDC is being replaced with a new unit,
be certain to transfer each of the fuses and relays
from the faulty PDC to the proper cavities of the
replacement PDC. Refer to Power Distribution in the
index of this service manual for the location of
complete PDC circuit diagrams and cavity assign-
ments.
(1) Position the PDC mounting bracket onto the
right front inner fender.
(2) Install and tighten the two screws that secure
the PDC mounting bracket to the right front inner
fender. Tighten the screws to 8.1 N·m (72 in. lbs.).
and
remove
the
B(+)
terminal
stud
cover from the end of the PDC (Fig. 4).
(6) Remove the nut that secures the eyelets of the
battery wire harness PDC take outs to the PDC B(+)
terminal stud.
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POWER DISTRIBUTION SYSTEMS
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REMOVAL AND INSTALLATION (Continued)
(5) Install the eyelets of the battery wire harness
PDC take outs onto the PDC B(+) terminal stud.
(6) Install and tighten the nut that secures the
eyelet of the battery wire harness PDC take outs to
the B(+) terminal stud. Tighten the nut to 10.8 N·m
(95 in. lbs.).
(7) Engage the tabs on the lower edge of the B(+)
terminal stud cover in the slots on the PDC housing,
then engage the latch on the top of the cover with
the latch receptacle on the PDC housing.
(8) Engage each of the retainers that secure the
headlamp and dash wire harness to the vehicle body
and chassis components. Refer to
Connector Loca-
tions
in the index of this service manual for the loca-
tion of more information on the headlamp and dash
wire harness retainer locations.
(9) Install all of the fasteners that secure each of
the headlamp and dash wire harness ground eyelets
to the vehicle body and chassis components. Refer to
Connector Locations
in the index of this service
manual for the location of more information on the
ground eyelet locations.
(10) Reconnect each of the headlamp and dash
wire harness connectors. Refer to
Connector Loca-
tions
in the index of this service manual for the loca-
tion of more information on the headlamp and dash
wire harness connector locations.
(11) Reconnect the battery negative cable.
Fig. 5 Power Distribution Center Remove/Install
1 – RIGHT FENDER
2 – POWER DISTRIBUTION CENTER
3 – BRACKET
IGNITION-OFF DRAW FUSE
The Ignition-Off Draw (IOD) fuse is removed from
Power Distribution Center (PDC) fuse cavity 16 (Fig.
7) when the vehicle is shipped from the assembly
plant. Dealer personnel must install the IOD fuse
when the vehicle is being prepared for delivery in
order to restore full electrical system operation.
NOTE: When removing or installing the IOD fuse, it
is important that the ignition switch be in the Off
position. Failure to place the ignition switch in the
Off position can cause the radio display to become
scrambled when the IOD fuse is installed. Remov-
ing and installing the IOD fuse again with the igni-
tion switch in the Off position will usually correct
the scrambled radio display condition.
Fig. 6 PDC Mounting Bracket Remove/Install
1 – RIGHT FRONT INNER FENDER
2 – PDC MOUNTING BRACKET
3 – SCREW
REMOVAL
(1) Turn the ignition switch to the Off position.
(2) Unlatch and remove the cover from the PDC.
(3) Remove the IOD fuse from fuse cavity 16 of the
PDC.
(4) Store the removed IOD fuse by inserting the
terminal blades of the fuse into the plastic fuse
holder formation that is molded into the underside of
the PDC cover.
(5) Install and latch the cover onto the PDC.
(3) Position the PDC and the headlamp and dash
wire harness unit in the engine compartment.
(4) Engage the mounting slots on the PDC housing
with the stanchions of the PDC mounting bracket
and push the unit downward until the mounting
bracket latches engage the mounting tabs on the
PDC housing.
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