2002 DODGE RAM fuse

UNDERHOOD LAMP - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 Z1 20BK GROUND
2 M1 20PK FUSED B(+)
WASHER FLUID LEVEL SWITCH - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 G29 18BK/WT WASHER FLUID SWITCH SENSE
2 Z1 18BK GROUND
WATER IN FUEL SENSOR (DIESEL)-2WAY
CAV CIRCUIT FUNCTION
A K104 18BK/LB SENSOR GROUND
B K1 18DG/RD WATER IN FUEL SENSOR SIGNAL
WIPER MOTOR-4WAY
CAV CIRCUIT FUNCTION
1 V4 16RD/YL WIPER SWITCH HIGH SPEED OUTPUT
2 V5 16DG WIPER PARK SWITCH SENSE
3 V6 16DB FUSED IGNITION SWITCH OUTPUT (RUN-ACC)
4 V3 16BR/WT LOW SPEED WIPER SWITCH OUTPUT
BR/BE8W-80 CONNECTOR PIN-OUTS 8W - 80 - 81

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
REMOVAL.............................3
INSTALLATION..........................4
CIRCUIT BREAKER
DESCRIPTION..........................4
DIAGNOSIS AND TESTING - CIRCUIT
BREAKER............................4
GENERATOR CARTRIDGE FUSE
DESCRIPTION..........................4
OPERATION............................4
REMOVAL.............................4
INSTALLATION..........................4
IOD FUSE
DESCRIPTION..........................5
OPERATION............................5
REMOVAL.............................6
INSTALLATION..........................6
JUNCTION BLOCK
DESCRIPTION..........................6
OPERATION............................7
DIAGNOSIS AND TESTING - JUNCTION
BLOCK..............................7
REMOVAL.............................7
INSTALLATION..........................8POWER DISTRIBUTION CENTER
DESCRIPTION..........................8
OPERATION............................8
REMOVAL.............................8
INSTALLATION.........................10
POWER OUTLET
DESCRIPTION.........................10
OPERATION...........................10
DIAGNOSIS AND TESTING - POWER OUTLET . 10
REMOVAL.............................11
INSTALLATION.........................11
HORN RELAY
DESCRIPTION.........................12
DIAGNOSIS AND TESTING - HORN RELAY . . . 12
REMOVAL.............................12
INSTALLATION.........................12
HEADLAMP RELAY
DESCRIPTION.........................13
REMOVAL.............................13
INSTALLATION.........................13
MICRO-RELAY
DESCRIPTION.........................13
OPERATION...........................14
DIAGNOSIS AND TESTING - MICRO-RELAY . . 14
REMOVAL.............................14
INSTALLATION.........................14
RELAY
DESCRIPTION.........................14
OPERATION...........................14
DIAGNOSIS AND TESTING - RELAY.........15
REMOVAL.............................15
INSTALLATION.........................15
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).
The power distribution system also incorporates
various types of circuit control and protection fea-
tures, including:
²Automatic resetting circuit breakers
²Blade-type fuses²Cartridge fuses
²Circuit splice blocks
²Flashers
²Relays.
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 toWir-
ing Diagramsfor complete circuit diagrams for the
various power distribution system components.
OPERATION
The power distribution system for this vehicle is
designed to provide safe, reliable, and centralized dis-
BR/BE8W-97 POWER DISTRIBUTION 8W - 97 - 1

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.
SPECIAL TOOLS
POWER DISTRIBUTION SYSTEMS
CIGAR LIGHTER OUTLET
DESCRIPTION
A cigar lighter is standard equipment on this
model. The cigar lighter is installed in the instru-
ment panel next to the ash receiver, which is located
near the center of the instrument panel, below the
radio. The cigar lighter base is secured by a snap fit
within the instrument panel.
The cigar lighter knob and heating element unit,
and the cigar lighter receptacle unit are available for
service. 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 receptacle shell. The receptacle shell
is connected to ground, and an insulated contact in
the bottom of the shell is connected to battery cur-
rent. The cigar lighter receives battery voltage from afuse in the junction block only when the ignition
switch is in the Accessory or On positions.
The 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 receptacle shell, the heat-
ing element resistor coil is grounded through its
housing to the receptacle 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 receptacle
shell.
Two small spring-clip retainers are located on
either side of the insulated contact inside the bottom
of the receptacle 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 receptacle 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 toCigar
Lighterin Wiring Diagrams.
WARNING: REFER TO THE PASSIVE RESTRAINT
SECTION OF THE SERVICE MANUAL BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
(1) Check the fused ignition switch output (run/ac-
cessory) fuse in the junction block. If OK, go to Step
2. If not OK, repair the shorted circuit 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 ignition switch
output (run/accessory) fuse in the junction block. If
OK, go to Step 3. If not OK, repair the open fused
Terminal Pick Kit 6680
8W - 97 - 2 8W-97 POWER DISTRIBUTIONBR/BE
POWER DISTRIBUTION (Continued)

ignition switch output (run/accessory) circuit to the
ignition switch as required.
(3) Turn the ignition switch to the Off position.
Remove the cigar lighter knob and element from the
cigar lighter receptacle. Check for continuity between
the inside circumference of the cigar lighter recepta-
cle and a good ground. There should be continuity. If
OK, go to Step 4. If not OK, go to Step 5.
(4) Turn the ignition switch to the On position.
Check for battery voltage at the insulated contact
located at the back of the cigar lighter receptacle. If
OK, replace the faulty cigar lighter knob and ele-
ment. If not OK, go to Step 5.
(5) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the cigar lighter receptacle from the instru-
ment panel and disconnect the wire harness connec-
tor. Check for continuity between the ground circuit
cavity of the cigar lighter wire harness connector and
a good ground. There should be continuity. If OK, go
to Step 6. If not OK, repair the open ground circuit to
ground as required.
(6) Connect the battery negative cable. Turn the
ignition switch to the On position. Check for battery
voltage at the fused ignition switch output (run/ac-
cessory) circuit cavity of the cigar lighter wire har-
ness connector. If OK, replace the faulty cigar lighter
receptacle. If not OK, repair the open fused ignition
switch output (run/accessory) circuit to the junction
block fuse as required.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Pull the cigar lighter knob and element out of
the cigar lighter receptacle base, or unsnap the pro-
tective cap from the power outlet receptacle base
(Fig. 1).
(3) Look inside the cigar lighter or power outlet
receptacle base and note the position of the rectangu-
lar retaining bosses of the mount that secures the
receptacle base to the instrument panel (Fig. 2).
(4) Insert a pair of external snap ring pliers into
the cigar lighter or power outlet receptacle base and
engage the tips of the pliers with the retaining
bosses of the mount.
(5) Squeeze the pliers to disengage the mount
retaining bosses from the receptacle base and, using
a gentle rocking motion, pull the pliers and the
receptacle base out of the mount.
(6) Pull the receptacle base away from the instru-
ment panel far enough to access the instrument
panel wire harness connector.
(7) Disconnect the instrument panel wire harness
connector from the cigar lighter or power outlet
receptacle base connector receptacle.
Fig. 1 Cigar Lighter and Power Outlet - Typical
1 - RECEPTACLE BASE
2 - KNOB & ELEMENT
3 - MOUNT
4 - WIRE HARNESS CONNECTOR
5 - POWER OUTLET
Fig. 2 Cigar Lighter and Power Outlet Remove/
Install
1 - KNOB AND ELEMENT
2 - RETAINING BOSSES-ENGAGE PLIERS HERE
3 - BASE
4 - PARTIALLY REMOVED
5 - EXTERNAL SNAP-RING PLIERS
6 - MOUNT
7 - BASE
BR/BE8W-97 POWER DISTRIBUTION 8W - 97 - 3
CIGAR LIGHTER OUTLET (Continued)

(8) Remove the cigar lighter or power outlet mount
from the instrument panel.
INSTALLATION
(1) Reconnect the instrument panel wire harness
connector to the cigar lighter or power outlet recep-
tacle base connector receptacle.
(2) Install the cigar lighter or power outlet mount
into the instrument panel.
(3) Align the splines on the outside of the cigar
lighter or power outlet receptacle base connector
receptacle with the grooves on the inside of the
mount.
(4) Press firmly on the cigar lighter or power out-
let receptacle base until the retaining bosses of the
mount are fully engaged in their receptacles.
(5) Install the cigar lighter knob and element into
the cigar lighter receptacle base, or the protective cap
into the power outlet receptacle base.
(6) Reconnect the battery negative cable.
CIRCUIT BREAKER
DESCRIPTION
Automatic resetting circuit breakers are used to
protect a system circuit from a short circuit or over-
load. Some examples of his condition can be caused
by an obstructed or stuck seat adjuster or power win-
dow motor.
The circuit breaker cannot be repaired and, if
faulty or damaged, it must be replaced.
DIAGNOSIS AND TESTING - CIRCUIT BREAKER
For circuit descriptions and diagrams, refer to Wir-
ing Diagrams.
(1) Locate the correct circuit breaker in the junc-
tion block. Pull out the circuit breaker slightly, but
be certain that the circuit breaker terminals still con-
tact the terminals in the junction block cavities.
(2) Connect the negative lead of a 12-volt DC volt-
meter to a good ground.
(3) With the voltmeter positive lead, check both
terminals of the circuit breaker for battery voltage.
If only one terminal has battery voltage, the circuit
breaker is faulty and must be replaced. If neither ter-
minal has battery voltage, repair the open circuit
from the Power Distribution Center (PDC) as
required.
GENERATOR CARTRIDGE
FUSE
DESCRIPTION
A 140 ampere generator cartridge fuse is used on
this model. The generator cartridge fuse is similar to
other cartridge fuses found in the Power Distribution
Center (PDC). This fuse has a color-coded plastic
housing and a clear plastic fuse conductor inspection
cover like other cartridge fuses, but has a higher cur-
rent rating and is connected and secured with screws
instead of being pushed onto male spade-type termi-
nals. The generator cartridge fuse cannot be repaired
and, if faulty or damaged, it must be replaced.
OPERATION
The generator cartridge fuse is secured between
the two B(+) terminal stud connection bus bars
within the Power Distribution Center (PDC). This
fuse protects the vehicle electrical system from dam-
age that could be caused by excessive charging sys-
tem output and/or excessive electrical system current
levels resulting from a faulty generator or faulty
charging system control circuits. If the current rating
of the fuse is exceeded, the fuse conductor melts to
open the generator output circuit connection to the
PDC. If a generator cartridge fuse fails, be certain to
completely inspect and test the vehicle charging sys-
tem before replacing the fuse and returning the vehi-
cle to service. Refer toCharging Systemfor the
charging system diagnostic procedures. Refer toWir-
ing Diagramsfor the location of complete PDC cir-
cuit diagrams.
REMOVAL
If a generator cartridge fuse fails, be certain to
inspect and test the vehicle charging system before
replacing the cartridge fuse and returning the vehicle
to service. Refer toCharging Systemin the index of
this service manual for the charging system diagnos-
tic procedures.
(1) Disconnect and isolate the battery negative
cable.
(2) Unlatch and remove the cover from the Power
Distribution Center (PDC).
(3) Remove the two screws that secure the genera-
tor cartridge fuse to the two B(+) terminal stud bus
bars within the PDC.
(4) Remove the generator cartridge fuse from the
PDC.
INSTALLATION
If a generator cartridge fuse fails, be certain to
inspect and test the vehicle charging system before
replacing the cartridge fuse and returning the vehicle
8W - 97 - 4 8W-97 POWER DISTRIBUTIONBR/BE
CIGAR LIGHTER OUTLET (Continued)

to service. Refer toCharging Systemin the index of
this service manual for the charging system diagnos-
tic procedures.
(1) Position the generator cartridge fuse onto the
two B(+) terminal stud bus bars within the PDC.
(2) Install and tighten the two screws that secure
the generator cartridge fuse to the two B(+) terminal
stud bus bars within the PDC. Tighten the screws to
3.4 N´m (30 in. lbs.).Be certain that both screws
are tightened to the proper torque value.
(3) Install and latch the cover onto the PDC.
(4) Reconnect the battery negative cable.
IOD FUSE
DESCRIPTION
All vehicles are equipped with an Ignition-Off
Draw (IOD) fuse (Fig. 3) that is disconnected within
the Junction Block when the vehicle is shipped from
the factory. Dealer personnel are to reconnect the
IOD fuse in the junction block as part of the prepa-
ration procedures performed just prior to new vehicle
delivery.
The left end of the instrument panel cover has a
snap-fit fuse access panel that can be removed to pro-
vide service access to the fuses in the junction block.
A finger recess is molded into the access panel for
easy removal. An adhesive-backed fuse layout map issecured to the instrument panel side of the access
panel to ensure proper fuse identification. The IOD
fuse is a 10 ampere mini blade-type fuse. The fuse is
secured within a black molded plastic fuse holder
and puller unit that serves both as a tool for discon-
necting and reconnecting the fuse in its junction
block cavity, and as a fuse holder that conveniently
stores the fuse in the same junction block cavity after
it has been disconnected.
CIRCUITS INCLUDED WITH IOD FUSE
²Cargo Lamp
²CHMSL
²Diagnostic Connector
²Dome Lamp
²Glove Box Lamp
²Map/Reading Lamps
²Power Mirrors
²Radio
²Under Hood Lamp
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
some 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
disconnected is to reduce the normal IOD of the vehi-
cle electrical system during new vehicle transporta-
tion 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 disconnected from JB fuse cavity
12 when the vehicle is shipped from the assembly
plant. Dealer personnel must reconnect 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 disconnecting the IOD fuse will not
eliminate IOD, but only reduce this normal condition.
Fig. 3 Ignition-Off Draw Fuse
1 - JUNCTION BLOCK
2 - IGNITION-OFF DRAW FUSE AND HOLDER
3 - LEFT INSTRUMENT PANEL END BRACKET
BR/BE8W-97 POWER DISTRIBUTION 8W - 97 - 5
GENERATOR CARTRIDGE FUSE (Continued)

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
theBatterysection of the service manual for the
location of additional service information covering
the battery.
REMOVAL
The Ignition-Off Draw (IOD) fuse is disconnected
from Junction Block (JB) fuse cavity 12 when the
vehicle is shipped from the assembly plant. Dealer
personnel must reconnect the IOD fuse when the
vehicle is being prepared for delivery in order to
restore full electrical system operation.
(1) Turn the ignition switch to the Off position.
(2) Remove the fuse access panel by unsnapping it
from the left outboard end of the instrument panel.
(3) Grasp the upper and lower tabs of the IOD
fuse holder unit in fuse cavity 12 (Fig. 4) of the JB
between the thumb and forefinger and pull the unit
firmly outward.
(4) Install the fuse access panel by snapping it
onto the left outboard end of the instrument panel.
INSTALLATION
The Ignition-Off Draw (IOD) fuse is disconnected
from Junction Block (JB) fuse cavity 12 when the
vehicle is shipped from the assembly plant. Dealer
personnel must reconnect the IOD fuse when the
vehicle is being prepared for delivery in order to
restore full electrical system operation.
(1) Turn the ignition switch to the Off position.
(2) To install the IOD fuse, use a thumb to press
the IOD fuse holder unit in fuse cavity 12 firmly into
the JB.
(3) Install the fuse access panel by snapping it
onto the left outboard end of the instrument panel.
JUNCTION BLOCK
DESCRIPTION
An electrical Junction Block (JB) is concealed
behind the left outboard end of the instrument panel
cover (Fig. 5). The JB combines the functions previ-
ously provided by a separate fuseblock module and
relay center, serves to simplify and centralize numer-
ous electrical components, and to distribute electrical
current to many of the accessory systems in the vehi-
cle. It also eliminates the need for numerous splice
connections and serves in place of a bulkhead connec-
Fig. 4 Ignition-Off Draw Fuse
1 - JUNCTION BLOCK
2 - IGNITION-OFF DRAW FUSE AND HOLDER
3 - LEFT INSTRUMENT PANEL END BRACKETFig. 5 Junction Block Location
1 - JUNCTION BLOCK
2 - FUSE ACCESS PANEL
8W - 97 - 6 8W-97 POWER DISTRIBUTIONBR/BE
IOD FUSE (Continued)

tor between many of the engine compartment, instru-
ment panel, and body wire harnesses. The JB houses
up to nineteen blade-type fuses (two standard-type
and seventeen mini-type), up to two blade-type auto-
matic resetting circuit breakers, the electronic combi-
nation turn signal and hazard warning flasher, and
one International Standards Organization (ISO)
micro-relay.
The molded plastic JB housing has integral mount-
ing brackets that are secured with two screws to the
left instrument panel end bracket. The left end of the
instrument panel cover has a snap-fit fuse access
panel that can be removed for service of the JB. A
fuse puller and spare fuse holders are located on the
back of the fuse access cover, as well as an adhesive-
backed fuse layout map to ensure proper fuse identi-
fication.
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 nine 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 toWiring Diagramsfor the location of com-
plete JB circuit diagrams.
DIAGNOSIS AND TESTING - JUNCTION BLOCK
The junction block does not incorporate any self
diagnostic capability. Most of the electrical circuits
incorporated into the vehicle must pass through the
junction block at one point or another. The most effi-
cient means of diagnosing a suspected junction block
problem involves a simple continuity tester or ohm
meter. Using the Wiring Diagrams as a guide trace
the problem circuit to the proper junction block cav-
ity and test all circuits in the effected circuit for
proper continuity. A open or high resistance circuit is
a sign of a problem. Some other possible junction
block problems to look for are:
²Loose fuse receptacle terminals.
²Loose relay / circuit breaker receptacle termi-
nals.
²Bent or distorted electrical circuit pins.
²Incorrect size fuse installed in junction block
fuse cavity.
²Dark areas identifying a source of excess heat.
²Defective fuse, relay or circuit breaker installed
in junction block cavity.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the fuse access bezel from the instru-
ment panel.
(3) Remove the steering column cover (Refer to 23
- BODY/INSTRUMENT PANEL/STEERING COL-
UMN OPENING COVER - REMOVAL).
(4) Remove the hood release handle retaining
screws and position the handle assembly out of the
way.
(5) Remove the lower knee blocker from the instru-
ment panel.
(6) Pull drivers side carpet down, out of the way.
(7) Remove the parking brake switch connector,
release linkage and retaining fasteners and position
the assembly out the drivers door opening.
(8) Remove the electrical ground connections,
located behind park brake mounting location.
(9) Remove the two junction block retaining
screws. To access the upper retaining screw a 15 inch
long #2 Phillips screwdriver will be required. Access
the upper screw through hole in dash support brace.
(10) Reach through the outboard side of the instru-
ment panel steering column opening to access and
disconnect all of the wire harness connectors from
the Junction Block (JB) connector receptacles (Fig.
6).
Fig. 6 Junction Block Remove/Install
1 - I.P. End Bracket
2 - Junction Block
3 - Screws
BR/BE8W-97 POWER DISTRIBUTION 8W - 97 - 7
JUNCTION BLOCK (Continued)