1998 DODGE RAM 1500 resistor

DRIVER DOOR MODULE
DESCRIPTION
A Driver Door Module (DDM) is used on all models
equipped with power locks, power windows, and
power mirrors. The DDM houses the following
switches:
²Power Lock Switch- The DDM includes a
two-way, momentary, resistor multiplexed switch to
control the power lock system.
²Power Mirror Selector Switch- A three-posi-
tion rocker switch in the DDM selects the right or
left power mirror for adjustment, or turns the power
mirror system Off.
²Power Mirror Adjustment Switches- Four
momentary, arrowhead shaped, directional switches
allow the driver to adjust the selected power mirror
in the Up, Down, Right, or Left directions.
²Power Window Lockout Switch- A two-way,
latching, push-button switch in the DDM allows the
vehicle operator to lock out the power window
switches on each passenger door so that the passen-
ger door power windows may be operated only from
the master switches in the DDM.
²Power Window Switches- The DDM houses a
two-way, momentary power window switch for the
driver side front door. This switch also has a second
detent in the Down direction and internal circuitry to
provide an Auto-Down feature for the driver side
front door power window. In addition to the power
window switch for its own door, the DDM houses
individual master switches for each passenger door
power window.
The DDM also incorporates several green Light-
Emitting Diodes (LEDs) that illuminate the power
lock and power window switch paddles, and the
power mirror switch directional buttons to improve
switch visibility in dark ambient lighting conditions.
The DDM cannot be adjusted or repaired and, if
faulty or damaged, the entire DDM unit must be
replaced.
OPERATION
The Driver Door Module (DDM) combines a power
lock switch, a driver power window switch with an
Auto-down feature, master switches for each passen-
ger door power window, a power window lockout
switch, a power mirror selector switch, and four
power mirror adjustment switches in a single unit.
The switches in the DDM can be diagnosed using
conventional diagnostic tools and methods.
Power Lock Switch
The DDM power lock switch circuitry is connected
in series between ground and the driver door switch
mux input of the instrument cluster. Each power lockswitch position (Lock, Unlock, and Neutral) provides
a different resistance value to the instrument cluster
input, which allows the instrument cluster to sense
the switch position. Based upon the power lock
switch input, the instrument cluster controls the bat-
tery and ground feed outputs to the individual power
lock motors to lock or unlock the door latches. The
Light-Emitting Diode (LED) in the DDM power lock
switch is connected to battery current through the
power window circuit breaker in the Integrated
Power Module (IPM) on a fused ignition switch out-
put (run-acc) circuit so that the switch will be illumi-
nated whenever the ignition switch is in the On or
Accessory positions.
Power Window Switches
The DDM power window switch circuitry is con-
nected to battery current through a circuit breaker in
the Integrated Power Module (IPM) on a fused igni-
tion switch output (run-acc) circuit so that the power
windows will operate whenever the ignition switch is
in the On or Accessory positions. Each two-way,
momentary master passenger power window switch
in the DDM provides battery current and ground to
the individual power window switches on each pas-
senger door so that the power window switch controls
the battery current and ground feeds to its respective
power window motor. The DDM switch for the driver
side front door power window is labeled ªAutoº and
includes an auto-down feature. When this switch is
depressed to a second momentary detent position and
released, the driver door power window is automati-
cally operated through an internal circuit and relay
to its fully lowered position. The Auto-down event is
cancelled if the switch paddle is depressed a second
time in either the Up or Down direction. When the
two position window lockout switch in the DDM is
depressed and latched in the lockout position, the
battery current feed to each of the individual passen-
ger power window switches is interrupted so that the
passenger door power windows can only be operated
from the master switches in the DDM. The window
lockout switch also controls the battery current feed
for the LED in each passenger power window switch
so that the switch will not be illuminated when it is
locked out.
Power Mirror Switches
The DDM power mirror switch circuitry is con-
nected to battery current through a fuse in the IPM
on a fused B(+) circuit so that the power mirrors
remain operational regardless of the ignition switch
position. A rocker type selector switch has three posi-
tions, one to select the right mirror, one to select the
left mirror, and a neutral Off position. After the right
or left mirror is selected, one of four directional but-
DRPOWER LOCKS 8N - 5

AIRBAG CONTROL MODULE
DESCRIPTION
The Airbag Control Module (ACM) is also some-
times referred to as the Occupant Restraint Control-
ler (ORC) (Fig. 7). The ACM is concealed below the
instrument panel center stack in the passenger com-
partment of the vehicle, where it is secured by three
screws to a stamped steel mounting bracket welded
onto the top of the floor panel transmission tunnel
just forward of the instrument panel center support
bracket. Concealed within a hollow in the center of
the die cast aluminum ACM housing is the electronic
circuitry of the ACM which includes a microproces-
sor, an electronic impact sensor, an electronic safing
sensor, and an energy storage capacitor. A stamped
metal cover plate is secured to the bottom of the
ACM housing with four screws to enclose and protect
the internal electronic circuitry and components.
An arrow printed on the label on the top of the
ACM housing provides a visual verification of the
proper orientation of the unit, and should always be
pointed toward the front of the vehicle. The ACM
housing has integral mounting flanges on three cor-
ners. The mounting flange to the left of the connector
receptacle has an integral locating pin on its lower
surface. Both left side flanges have round mounting
holes, while the flange on the right side has a slotted
mounting hole. A molded plastic electrical connector
with two receptacles, one containing twenty-four ter-
minal pins and the other containing thirty-two termi-
nal pins, exits the rearward facing side of the ACM
housing. These terminal pins connect the ACM to the
vehicle electrical system through two dedicated takeouts and connectors of the instrument panel wire
harness.
The impact sensor and safing sensor internal to
the ACM are calibrated for the specific vehicle, and
are only serviced as a unit with the ACM. In addi-
tion, there are unique versions of the ACM for light
and heavy-duty models, and for vehicles with or
without the optional side curtain airbags. The ACM
cannot be repaired or adjusted and, if damaged or
faulty, it must be replaced.
OPERATION
The microprocessor in the Airbag Control Module
(ACM) contains the supplemental restraint system
logic circuits and controls all of the supplemental
restraint system components. The ACM uses
On-Board Diagnostics (OBD) and can communicate
with other electronic modules in the vehicle as well
as with the DRBIIItscan tool using the Programma-
ble Communications Interface (PCI) data bus net-
work. This method of communication is used for
control of the airbag indicator in the ElectroMechani-
cal Instrument Cluster (EMIC) and for supplemental
restraint system diagnosis and testing through the
16-way data link connector located on the driver side
lower edge of the instrument panel. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER/AIRBAG
INDICATOR - OPERATION).
The ACM microprocessor continuously monitors all
of the supplemental restraint system electrical cir-
cuits to determine the system readiness. If the ACM
detects a monitored system fault, it sets an active
and stored Diagnostic Trouble Code (DTC) and sends
electronic messages to the EMIC over the PCI data
bus to turn on the airbag indicator. An active fault
only remains for the duration of the fault, or in some
cases for the duration of the current ignition switch
cycle, while a stored fault causes a DTC to be stored
in memory by the ACM. For some DTCs, if a fault
does not recur for a number of ignition cycles, the
ACM will automatically erase the stored DTC. For
other internal faults, the stored DTC is latched for-
ever.
In standard cab models, the ACM also monitors a
resistor multiplexed input from the passenger airbag
on/off switch and provides a control output for the
Off indicator in the switch through a passenger air-
bag indicator driver circuit. If the passenger airbag
on/off switch is set to the Off position, the ACM turns
on the passenger airbag on/off switch Off indicator
and will internally disable the passenger airbag from
being deployed. The ACM also turns on the on/off
switch Off indicator for about seven seconds each
time the ignition switch is turned to the On position
as a bulb test. Following the bulb test, the ACM con-
trols the status of the Off indicator based upon the
Fig. 7 Airbag Control Module
1 - AIRBAG CONTROL MODULE
2 - ORIENTATION ARROW
3 - LABEL
4 - CONNECTOR RECEPTACLE (2)
DRRESTRAINTS 8O - 11

The passenger airbag on/off switch housing is con-
structed of molded plastic and has three integral
mounting tabs. These mounting tabs are used to
secure the switch to the back of the molded plastic
switch face plate with three small screws. The
molded plastic face plate also has three integral
mounting tabs that are used to secure the switch and
face plate unit to the instrument panel center bezel
with three additional screws. A molded plastic con-
nector receptacle on the back of the switch housing
connects the switch to the vehicle electrical system
through a dedicated take out and connector of the
instrument panel wire harness. The molded plastic
harness connector insulator is keyed and latched to
ensure proper and secure switch electrical connec-
tions. The passenger airbag on/off switch cannot be
adjusted or repaired and, if faulty or damaged, the
switch must be replaced.
OPERATION
The passenger airbag on/off switch allows the cus-
tomer to turn the passenger airbag function On or
Off to accommodate certain uses of the right front
seating position where airbag protection may not be
desired. See the owner's manual in the vehicle glove
box for specific recommendations on when to enable
or disable the passenger airbag. The Off indicator of
the switch will be illuminated whenever the switch is
turned to the Off position and the ignition switch is
in the On position.
The ignition key is the only key or object that
should ever be inserted into the key cylinder actuator
of the switch. The on/off switch requires only a par-
tial key insertion to fully depress a spring-loaded
locking plunger. The spring-loaded locking plunger
prevents the user from leaving the key in the switch.
The key will be automatically ejected when force is
not applied. To actuate the passenger airbag on/off
switch, insert the ignition key into the switch key
actuator far enough to fully depress the plunger, then
rotate the actuator to the desired switch position.
When the switch key actuator is rotated to its clock-
wise stop (the key actuator slot will be aligned with
the Off indicator), the Off indicator is illuminated
and the passenger airbag is disabled. When the
switch is rotated to its counterclockwise stop (the key
actuator slot will be in a vertical position), the Off
indicator will be extinguished and the passenger air-
bag is enabled.The passenger airbag on/off switch connects one of
two internal resistors in series between the passen-
ger airbag mux switch sense and passenger airbag
mux switch return circuits of the Airbag Control
Module (ACM). The ACM continually monitors the
resistance in these circuits to determine the switch
position that has been selected. When the switch is
in the Off position, the ACM provides a ground input
to the switch through the passenger airbag indicator
driver circuit, which energizes the Light-Emitting
Diode (LED) that illuminates the Off indicator of the
switch.
The ACM will also illuminate the Off indicator of
the switch for about seven seconds each time the
ignition switch is turned to the On position as a bulb
test. The ACM will store a Diagnostic Trouble Code
(DTC) for any fault it detects in the passenger airbag
on/off switch or Off indicator circuits, and will illumi-
nate the airbag indicator in the instrument cluster if
a fault is detected. For proper diagnosis of the pas-
senger airbag on/off switch or the ACM, a DRBIIIt
scan tool is required. Refer to the appropriate diag-
nostic information.
REMOVAL
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) Remove the center bezel from the instrument
panel. (Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL CENTER BEZEL -
REMOVAL).
(3) From the back of the center bezel, remove the
three screws that secure the passenger airbag on/off
switch and face plate unit to the back of the bezel
(Fig. 40).
(4) Remove the passenger airbag on/off switch and
face plate from the center bezel as a unit.
DRRESTRAINTS 8O - 43
PASSENGER AIRBAG ON/OFF SWITCH (Continued)

is released before parking the wiper blades near the
base of the windshield. If the control knob is held in
the depressed Wash position for more than about
thirty seconds, washer system operation will be sus-
pended until the control knob is released for about
two seconds then cycled back to the Wash position.
OPERATION
The wiper and washer system is designed to pro-
vide the vehicle operator with a convenient, safe, and
reliable means of maintaining visibility through the
windshield glass. The various components of this sys-
tem are designed to convert electrical energy pro-
duced by the vehicle electrical system into the
mechanical action of the wiper blades to wipe the
outside surface of the glass, as well as into the
hydraulic action of the washer system to apply
washer fluid stored in an on-board reservoir to the
area of the glass to be wiped. When combined, these
components provide the means to effectively main-
tain clear visibility for the vehicle operator by remov-
ing excess accumulations of rain, snow, bugs, mud, or
other minor debris from the outside windshield glass
surface that might be encountered while driving the
vehicle under numerous types of inclement operating
conditions.
The vehicle operator initiates all wiper and washer
system functions with the control knob on the end of
the control stalk of the multi-function switch that
extends from the left side of the steering column, just
below the steering wheel. Rotating the control knob
on the end of the control stalk, selects the Off, Delay,
Low, or High wiper system operating modes. In the
Delay mode, the control knob also allows the vehicle
operator to select from one of five intermittent wipe
Delay intervals. Depressing the control knob towards
the steering column actuates the momentary washer
system switch, which selects the Wash, Wipe-After-
Wash, and Pulse Wipe Modes depending upon when
and how long the switch is held closed. The multi-
function switch provides hard wired resistor multi-
plexed inputs to the instrument cluster for all of the
wiper and washer system functions. The instrument
cluster then sends electronic messages to the Front
Control Module (FCM) over the Programmable Com-
munications Interface (PCI) data bus requesting the
appropriate wiper and washer system operating
modes.
Wiper and washer system operation are completely
controlled by the instrument cluster and FCM logic
circuits, and that logic will only allow these systems
to operate when the ignition switch is in the Acces-
sory or On positions. Battery current is directed from
a B(+) fuse in the Integrated Power Module (IPM) to
the wiper on/off relay and the wiper high/low relay in
the IPM through a fused B(+) circuit. The FCM useslow side drivers to control wiper system operation by
energizing or de-energizing the wiper high/low and
wiper on/off relays. The FCM uses a high side driver
to control the operation of the washer pump motor
unit. The multi-function switch circuitry receives a
clean ground output from the instrument cluster on a
multi-function switch return circuit, then provides
resistor multiplexed inputs to the instrument cluster
on an intermittent wipe mux circuit to indicate the
selected wiper system mode and on a wash/beam
select mux circuit to indicate the selected washer sys-
tem mode.
The hard wired circuits and components of the
wiper and washer system may be diagnosed and
tested using conventional diagnostic tools and proce-
dures. However, conventional diagnostic methods
may not prove conclusive in the diagnosis of the
instrument cluster, the FCM, or the electronic mes-
sage inputs to or outputs from the instrument cluster
or FCM that control the wiper and washer system
operating modes. The most reliable, efficient, and
accurate means to diagnose the instrument cluster or
the FCM inputs and outputs related to the various
wiper and washer system operating modes requires
the use of a DRBIIItscan tool. Refer to the appro-
priate diagnostic information.
OPERATING MODES
Following are paragraphs that briefly describe the
operation of each of the wiper and washer system
operating modes.
CONTINUOUS WIPE MODE
When the Low position of the control knob on the
control stalk of the multi-function switch is selected
the instrument cluster sends an electronic wiper
switch low message to the FCM, then the FCM ener-
gizes the wiper on/off relay. This directs battery cur-
rent through the normally open contacts of the
energized wiper on/off relay and the normally closed
contacts of the de-energized wiper high/low relay to
the low speed brush of the wiper motor, causing the
wipers to cycle at low speed.
When the High position of the control knob is
selected the instrument cluster sends an electronic
wiper switch high message to the FCM, then the
FCM energizes both the wiper on/off relay and the
wiper high/low relay. This directs battery current
through the normally open contacts of the energized
wiper on/off relay and the normally open contacts of
the energized wiper high/low relay to the high speed
brush of the wiper motor, causing the wipers to cycle
at high speed.
When the Off position of the multi-function switch
control knob is selected, the instrument cluster sends
an electronic wiper switch off message to the FCM. If
8R - 4 WIPERS/WASHERSDR
WIPERS/WASHERS (Continued)

(2) From the underside of the cowl plenum cover/
grille panel, reconnect the cowl plenum and washer
nozzle hoses to the three barbed nipples of the check
valve.
(3) Reinstall the cowl plenum cover/grille panel
over the cowl plenum. (Refer to 23 - BODY/EXTERI-
OR/COWL GRILLE - INSTALLATION).
(4) Close and latch the hood.
(5) Reinstall both wiper arms onto the wiper piv-
ots. (Refer to 8 - ELECTRICAL/WIPERS/WASHERS/
WIPER ARM - INSTALLATION).
WASHER FLUID LEVEL
SWITCH
DESCRIPTION
The washer fluid level switch is a single pole, sin-
gle throw reed-type switch mounted on the outboard
side of the of the washer reservoir in the engine com-
partment (Fig. 6). Only the molded plastic switch
mounting flange and the integral connector recepta-
cle are visible when the switch is installed in the res-
ervoir. A short nipple formation extends from the
inner surface of the switch mounting flange, and a
barb on the nipple near the switch mounting flange
is pressed through a rubber grommet seal installed
in the mounting hole of the reservoir.
A small, molded plastic float has two pivot pins
near its center that are snapped into two receptacles
near the ends of two stanchions that extend toward
the float from the switch nipple formation. A small
magnet is secured within the end of the float nearestthe switch nipple formation, and a reed switch is con-
cealed within the nipple. A diagnostic resistor is con-
nected between the two switch terminals within the
switch mounting flange. The washer fluid level
switch cannot be adjusted or repaired. If faulty or
damaged, the switch must be replaced.
OPERATION
The washer fluid level switch uses a pivoting,
oblong float to monitor the level of the washer fluid
in the washer reservoir. The float contains a small
magnet. When the float pivots, the proximity of this
magnet to a stationary reed switch within the nipple
formation of the switch changes. When the fluid level
in the washer reservoir is at or above the float level,
the float moves to a vertical position, the influence of
the float magnetic field is removed from the reed
switch, and the normally open reed switch contacts
open. When the fluid level in the washer reservoir
falls below the level of the pivoting float, the float
moves to a horizontal position, the influence of the
float magnetic field is applied to the reed switch, and
the contacts of the normally open reed switch close.
The washer fluid level switch is connected to the
vehicle electrical system through a dedicated take
out and connector of the right (except diesel engines)
or left (diesel engines only) headlamp and dash wire
harness. The switch is connected in series between a
clean ground output of the Front Control Module
Fig. 5 Check Valve Remove/Install
1 - WASHER NOZZLE HOSE (RIGHT)
2 - CHECK VALVE
3 - ROUTING CLIP
4 - COWL PLENUM WASHER HOSE
5 - COWL PLENUM COVER/GRILLE PANEL (UNDERSIDE)
6 - WASHER NOZZLE HOSE (LEFT)
Fig. 6 Washer Fluid Level Switch
1 - MOUNTING FLANGE
2 - BARBED NIPPLE
3 - FLOAT
4 - RESERVOIR
5 - GROMMET SEAL
6 - PIVOT
7 - MAGNET
8 - CONNECTOR RECEPTACLE
DRWIPERS/WASHERS 8R - 9
CHECK VALVE (Continued)

(7) Reinstall both wiper arms onto the wiper piv-
ots. (Refer to 8 - ELECTRICAL/WIPERS/WASHERS/
WIPER ARM - INSTALLATION).
WASHER PUMP/MOTOR
DESCRIPTION
The washer pump/motor unit (Fig. 12) is located on
the rearward facing surface of the washer reservoir,
in the right (except diesel engine) or left (diesel
engine only) front corner of the engine compartment.
A small permanently lubricated and sealed electric
motor is coupled to the rotor-type washer pump. A
seal flange with a barbed inlet nipple on the pump
housing passes through a rubber grommet seal
installed in a dedicated mounting hole of the washer
reservoir. When the pump is installed in the reser-
voir a barbed outlet nipple on the pump housing con-
nects the unit to the washer system through a short
washer reservoir hose.
The washer pump/motor unit is retained on the
reservoir by the interference fit between the barbed
pump inlet nipple and the grommet seal, which is a
light press fit. The top of the washer pump is also
secured to the washer reservoir by the use of a snappost on the motor housing and a snap post receptacle
molded into the reservoir that allows for mounting of
the washer pump without the use of fasteners. An
integral connector receptacle on the top of the motor
housing connects the unit to the vehicle electrical
system. The washer pump/motor unit cannot be
repaired. If faulty or damaged, the entire washer
pump/motor unit must be replaced.
OPERATION
The washer pump/motor unit features a small
Direct Current (DC) electric motor. The motor is con-
nected to the vehicle electrical system through a sin-
gle take out and two-cavity connector of the right
(except diesel engine) or left (diesel engine only)
headlamp and dash wire harness. The motor is
grounded at all times through another take out of
the right (except diesel engine) or left (diesel engine
only) headlamp and dash wire harness. On models
without the diesel engine, a single eyelet terminal
connector is secured by a nut to a ground stud
located on the right front fender inner shield in the
engine compartment. On models with a diesel engine,
an eyelet terminal connector is secured by a ground
screw to the left front fender inner shield in the
engine compartment. The motor receives battery cur-
rent on a washer pump/motor control circuit.
The washer pump/motor control circuit is energized
through a high side driver within the Front Control
Module (FCM) whenever the FCM receives an elec-
tronic message requesting washer system operation
from the instrument cluster over the Programmable
Communications Interface (PCI) data bus. The
instrument cluster monitors a resistor multiplexed
hard wired input from the momentary washer switch
contacts within the multi-function switch on the
steering column to determine when it should issue
the electronic message requesting washer system
operation.
Washer fluid is gravity-fed from the washer reser-
voir to the inlet side of the washer pump. When the
pump motor is energized, the motor spins the rotor
within the washer pump. The spinning pump rotor
pressurizes the washer fluid and forces it through
the pump outlet nipple, the washer plumbing, and
the washer nozzles onto the windshield glass.
The washer pump/motor unit may be diagnosed
using conventional diagnostic tools and methods.
However, conventional diagnostic methods may not
prove conclusive in the diagnosis of the instrument
cluster, the FCM, or the electronic message inputs to
or outputs from the instrument cluster and the FCM
that control the operation of the washer pump/motor
unit. The most reliable, efficient, and accurate means
to diagnose the washer pump/motor unit, the instru-
ment cluster, the FCM, or the electronic message
Fig. 12 Washer Pump/Motor
1 - MOTOR
2 - SNAP POST
3 - CONNECTOR RECEPTACLE
4 - PUMP
5 - OUTLET NIPPLE
6 - INLET NIPPLE
7 - FILTER SCREEN
DRWIPERS/WASHERS 8R - 13
WASHER NOZZLE (Continued)

INSTALLATION
NOTE: The notched end of the wiper element flexor
should always be oriented towards the end of the
wiper blade that is nearest to the wiper pivot.
(1) Lift the wiper arm off of the windshield glass,
until the wiper arm hinge is in its over-center posi-
tion.
(2) Position the wiper blade near the hook forma-
tion on the tip of the arm with the notched end of the
wiper element flexor oriented towards the end of the
wiper arm that is nearest to the wiper pivot.
(3) Insert the hook formation on the tip of the
wiper arm through the opening in the wiper blade
superstructure ahead of the wiper blade pivot block/
latch unit far enough to engage the pivot block into
the hook (Fig. 21).
(4) Slide the wiper blade pivot block/latch up into
the hook formation on the tip of the wiper arm until
the latch release tab snaps into its locked position.
Latch engagement will be accompanied by an audible
click.
(5) Gently lower the wiper blade onto the glass.
WIPER HIGH/LOW RELAY
DESCRIPTION
The wiper high/low relay is located in the Inte-
grated Power Module (IPM) in the engine compart-
ment near the battery. The wiper high/low relay is a
conventional International Standards Organization
(ISO) micro relay (Fig. 22). Relays conforming to the
ISO specifications have common physical dimensions,
current capacities, terminal patterns, and terminal
functions. The relay is contained within a small, rect-
angular, molded plastic housing and is connected to
all of the required inputs and outputs by five integralmale spade-type terminals that extend from the bot-
tom of the relay base.
The wiper high/low relay cannot be adjusted or
repaired and, if faulty or damaged, the unit must be
replaced.
OPERATION
The wiper high/low relay is an electromechanical
switch that uses a low current input from the Front
Control Module (FCM) to control a high current out-
put to the wiper motor. The movable common feed
contact point is held against the fixed normally
closed contact point by spring pressure. When the
relay coil is energized, an electromagnetic field is
produced by the coil windings. This electromagnetic
field draws the movable relay contact point away
from the fixed normally closed contact point, and
holds it against the fixed normally open contact
point. When the relay coil is de-energized, spring
pressure returns the movable contact point back
against the fixed normally closed contact point. A
resistor is connected in parallel with the relay coil in
the relay, and helps to dissipate voltage spikes and
electromagnetic interference that can be generated as
the electromagnetic field of the relay coil collapses.
The wiper high/low relay terminals are connected
to the vehicle electrical system through a connector
receptacle in the Integrated Power Module (IPM).
The inputs and outputs of the wiper high/low relay
include:
²Common Feed Terminal- The common feed
terminal (30) is connected to the output of the wiper
on/off relay at all times through the wiper on/off
relay output circuit.
²Coil Ground Terminal- The coil ground termi-
nal (85) is connected to a control output of the Front
Control Module (FCM) through a wiper high/low
relay control circuit. The FCM controls wiper motor
operation by controlling a ground path through this
circuit.
²Coil Battery Terminal- The coil battery ter-
minal (86) receives battery current when the ignition
switch is in the On or Accessory positions from a fuse
in the Integrated Power Module (IPM) through a
fused ignition switch output (run-acc) circuit.
²Normally Open Terminal- The normally open
terminal (87) is connected to the high speed brush of
the wiper motor through a wiper high/low relay high
speed output circuit, and is connected to the high
speed brush whenever the relay is energized.
²Normally Closed Terminal- The normally
closed terminal (87A) is connected to the low speed
brush of the wiper motor through a wiper high/low
relay low speed output circuit, and is connected to
the low speed brush whenever the relay is de-ener-
gized.
Fig. 22 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
8R - 20 WIPERS/WASHERSDR
WIPER BLADE (Continued)

The wiper on/off relay cannot be adjusted or
repaired and, if faulty or damaged, the unit must be
replaced.
OPERATION
The wiper on/off relay is an electromechanical
switch that uses a low current input from the Front
Control Module (FCM) to control a high current out-
put to the wiper motor. The movable common feed
contact point is held against the fixed normally
closed contact point by spring pressure. When the
relay coil is energized, an electromagnetic field is
produced by the coil windings. This electromagnetic
field draws the movable relay contact point away
from the fixed normally closed contact point, and
holds it against the fixed normally open contact
point. When the relay coil is de-energized, spring
pressure returns the movable contact point back
against the fixed normally closed contact point. A
resistor is connected in parallel with the relay coil in
the relay, and helps to dissipate voltage spikes and
electromagnetic interference that can be generated as
the electromagnetic field of the relay coil collapses.
The wiper on/off relay terminals are connected to
the vehicle electrical system through a connector
receptacle in the Integrated Power Module (IPM).
The inputs and outputs of the wiper on/off relay
include:
²Common Feed Terminal- The common feed
terminal (30) is connected to the common feed termi-
nal of the wiper high/low relay at all times through
the wiper on/off relay output circuit.
²Coil Ground Terminal- The coil ground termi-
nal (85) is connected to a control output of the Front
Control Module (FCM) through a wiper on/off relay
control circuit. The FCM controls wiper motor opera-
tion by controlling a ground path through this cir-
cuit.
²Coil Battery Terminal- The coil battery ter-
minal (86) receives battery current at all times from
a fuse in the IPM through a fused ignition switch
output (run-acc) circuit.
²Normally Open Terminal- The normally open
terminal (87) receives battery current at all times
from a fuse in the IPM through a fused ignition
switch output (run-acc) circuit, and provides battery
current to the wiper on/off relay output circuit when-
ever the relay is energized.²Normally Closed Terminal- The normally
closed terminal (87A) is connected to ground at all
times through a take out of the left headlamp and
dash wire harness with an eyelet terminal connector
that is secured by a screw to the front end sheet
metal, and is connected to the wiper on/off relay out-
put circuit whenever the relay is de-energized.
The wiper on/off relay may be diagnosed using con-
ventional diagnostic tools and methods. However,
conventional diagnostic methods may not prove con-
clusive in the diagnosis of the instrument cluster, the
Front Control Module (FCM), or the electronic mes-
sage inputs to or outputs from the instrument cluster
and the FCM that control the operation of the wiper
on/off relay. The most reliable, efficient, and accurate
means to diagnose the wiper on/off relay, the instru-
ment cluster, the FCM, or the electronic message
inputs and outputs related to the wiper on/off relay
operation requires the use of a DRBIIItscan tool.
Refer to the appropriate diagnostic information.
DIAGNOSIS AND TESTING - WIPER ON/OFF
RELAY
The wiper on/off relay (Fig. 28) is located in the
Integrated Power Module (IPM) in the engine com-
partment near the battery. Refer to the appropriate
wiring information. The wiring information 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 connectors, splices
and grounds.
Fig. 28 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
DRWIPERS/WASHERS 8R - 25
WIPER ON/OFF RELAY (Continued)