2003 JEEP GRAND CHEROKEE start switch

(4) Install airbag module. Refer to Group 8M, Pas-
sive Restraint Systems.
(5) Connect negative battery cable.
VACUUM RESERVOIR
DESCRIPTION
The vacuum reservoir is a plastic storage tank con-
nected to an engine vacuum source by vacuum lines.
OPERATION
The vacuum reservoir is used to supply the vac-
uum needed to maintain proper speed control opera-
tion when engine vacuum drops, such as in climbing
a grade while driving. A one-way check valve is used
in the vacuum line between the reservoir and the
vacuum source. This check valve is used to trap
engine vacuum in the reservoir. On certain vehicle
applications, this reservoir is shared with the heat-
ing/air-conditioning system. The vacuum reservoir
cannot be repaired and must be replaced if faulty.
DIAGNOSIS AND TESTING - VACUUM
RESERVOIR
(1) Disconnect vacuum hose at speed control servo
and install a vacuum gauge into the disconnected
hose.
(2) Start engine and observe gauge at idle. Vac-
uum gauge should read at least ten inches of mer-
cury.
(3) If vacuum is less than ten inches of mercury,
determine source of leak. Check vacuum line to
engine for leaks. Also check actual engine intake
manifold vacuum. If manifold vacuum does not meet
this requirement, check for poor engine performance
and repair as necessary.
(4) If vacuum line to engine is not leaking, check
for leak at vacuum reservoir. To locate and gain
access to reservoir, refer to Vacuum Reservoir Remov-
al/Installation in this group. Disconnect vacuum line
at reservoir and connect a hand-operated vacuum
pump to reservoir fitting. Apply vacuum. Reservoir
vacuum should not bleed off. If vacuum is being lost,
replace reservoir.
(5) Verify operation of one-way check valve and
check it for leaks.
(a) Locate one-way check valve. The valve is
located in vacuum line between vacuum reservoir
and engine vacuum source. Disconnect vacuum
hoses (lines) at each end of valve.
(b) Connect a hand-operated vacuum pump to
reservoir end of check valve. Apply vacuum. Vac-
uum should not bleed off. If vacuum is being lost,
replace one-way check valve.
(c) Connect a hand-operated vacuum pump to
vacuum source end of check valve. Apply vacuum.
Vacuum should flow through valve. If vacuum is
not flowing, replace one-way check valve. Seal the
fitting at opposite end of valve with a finger and
apply vacuum. If vacuum will not hold, diaphragm
within check valve has ruptured. Replace valve.
REMOVAL
The vacuum reservoir is located in the right/front
corner of the vehicle behind the front bumper fascia
(Fig. 8).
(1) Remove front bumper and grill assembly.
(2) Remove 1 support bolt near front of reservoir
(Fig. 8).
(3) Remove 2 reservoir mounting bolts.
(4) Remove reservoir from vehicle to gain access to
vacuum hose (Fig. 9). Disconnect vacuum hose from
reservoir fitting at rear of reservoir.
Fig. 7 Speed Control Switches
1 - MOUNTING SCREW
2 - SPEED CONTROL SWITCHES
8P - 8 SPEED CONTROLWJ
SWITCH (Continued)

switch, or when the ªLockº button on the Remote
Keyless Entry (RKE) transmitter is depressed. The
powerlock switch will not initiate the pre-arming
sequence if the key is in the ignition switch. When
the VTA is pre-armed, the arming sequence is
delayed until all of the doors, the tailgate and the
flip-up glass are closed.
ARMING
Passive arming of the VTSS occurs when the vehi-
cle is exited with the key removed from the ignition
switch, the headlamps are turned off, and the doors
are locked while they are open using the power lock
switch. The power lock switch will not function if the
key is in the ignition switch or the headlamps are
turned on with the driver side front door open. The
VTSS will not arm if the driver side front door is
locked using the key in the lock cylinder or using the
mechanical lock button. Active arming of the VTSS
occurs when the ªLockº button on the Remote Key-
less Entry (RKE) transmitter is depressed to lock the
vehicle, even if the doors and/or the liftgate are open
when the RKE transmitter Lock button is depressed.
However, the VTSS arming will not be complete until
all of the doors, the liftgate and the liftgate flip-up
glass are closed. On vehicles equipped with the hood
ajar switch, VTSS arming will complete if the hood is
open, but the underhood area will not be protected
unless the hood is closed when the VTSS is armed.
Following successful passive or active VTSS arm-
ing, the VTSS indicator on the top of the instrument
panel will flash rapidly for about sixteen seconds
after the illuminated entry system times out. This
indicates that VTSS arming is in progress. Once the
sixteen second arming function is successfully com-
pleted, the indicator will flash at a slower rate, indi-
cating that the VTSS is armed.
DISARMING
Passive disarming of the VTSS occurs when the
vehicle is unlocked using the key to unlock the driver
side front door. Active disarming of the VTSS occurs
when the vehicle is unlocked by depressing the
ªUnlockº button of the Remote Keyless Entry (RKE)
transmitter. Once the alarm has been activated,
either disarming method will also deactivate the
alarm. Depressing the ªPanicº button on the RKE
transmitter will also disarm the VTSS, but the horn
will continue to pulse and the exterior lamps will
continue to flash for about three minutes as part of
the Panic feature function. The Panic feature is over-
ridden if the ªPanicº button is depressed a second
time, or if a vehicle speed of about 24 kilometers-per-
hour (15 miles-per-hour) is attained.POWER-UP MODE
When the armed VTSS senses that the battery has
been disconnected and reconnected, it enters its pow-
er-up mode. In the power-up mode the alarm system
remains armed following a battery failure or discon-
nect. If the VTSS was armed prior to a battery dis-
connect or failure, the technician or vehicle operator
will have to actively or passively disarm the alarm
system after the battery is reconnected. The pow-
er-up mode will also apply if the battery goes dead
while the system is armed, and battery jump-starting
is then attempted. The VTSS will be armed until it is
actively or passively disarmed. If the VTSS is in the
disarmed mode prior to a battery disconnect or fail-
ure, it will remain disarmed after the battery is
reconnected or replaced, or if jump-starting is
attempted.
ALARM
The VTA alarm output varies by the version of the
VTA with which the vehicle is equipped. In all cases,
the alarm provides both visual and audible outputs;
however, the time intervals of these outputs vary by
the requirements of the market for which the vehicle
is manufactured. In all cases, the visual output will
be a flashing of the exterior lamps. For vehicles
equipped with North American or the base version of
the VTA, the audible output will be the pulsing of the
horn. For vehicles with the premium version of the
VTA, the audible output will be the cycling of the
siren. The inputs that will trigger the alarm include
the door ajar switch, the flip-up glass ajar switch,
and in vehicles built for certain markets where they
are required, the hood ajar switch and the Intrusion
Transceiver Module (ITM).
TAMPER ALERT
The VTSS tamper alert feature will sound the horn
(or the alarm siren for the premium version) three
times upon VTA disarming, if the alarm was trig-
gered and has since timed-out (about eighteen min-
utes). This feature alerts the vehicle operator that
the VTA alarm was activated while the vehicle was
unattended.
INTRUSION ALARM
The Intrusion Alarm is an exclusive feature of the
premium version of the VTA, which is only available
in certain markets, where it is required. When the
VTA is armed, a motion sensor in the Intrusion
Transceiver Module (ITM) monitors the interior of
the vehicle for movement. If motion is detected, the
ITM sends a message to the BCM over the PCI bus
to invoke the visual alarm feature, and sends a mes-
sage to the alarm siren over a dedicated serial bus to
invoke the audible alarm feature. The motion detec-
WJVEHICLE THEFT SECURITY 8Q - 3
VEHICLE THEFT SECURITY (Continued)

tion feature of the ITM can be disabled by depressing
the ªLockº button on the RKE transmitter three
times or cycling the key in the driver door cylinder
from the center to lock position within fifteen seconds
during VTA arming, while the security indicator is
still flashing rapidly. The VTA provides a single short
siren ªchirpº as an audible conformation that the
motion detect disable request has been received. The
ITM must be electronically enabled in order for the
intrusion alarm to perform as designed. The intru-
sion alarm function of the ITM is enabled on vehicles
equipped with this option at the factory, but a service
replacement ITM must be configured and enabled by
the dealer using the DRBIIItscan tool. Refer to the
appropriate diagnostic information.
OPERATION - SENTRY KEY IMMOBILIZER
SYSTEM
The Sentry Key Immobilizer System (SKIS) is
designed to provide passive protection against unau-
thorized vehicle use by disabling the engine after
about two seconds of running, whenever any method
other than a valid Sentry Key is used to start the
vehicle. The SKIS is considered a passive protection
system because it is always active when the ignition
system is energized and does not require any cus-
tomer intervention. The SKIS uses Radio Frequency
(RF) communication to obtain confirmation that the
key in the ignition switch is a valid key for operating
the vehicle. The microprocessor-based SKIS hard-
ware and software also uses messages to communi-
cate with other modules in the vehicle over the
Programmable Communications Interface (PCI) data
bus. (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/COMMUNICATION - OPERA-
TION).
Pre-programmed Sentry Key transponders are pro-
vided with the vehicle from the factory. Each Sentry
Key Immobilizer Module (SKIM) will recognize a
maximum of eight Sentry Keys. If the customer
would like additional keys other than those provided
with the vehicle, they may be purchased from any
authorized dealer. These additional keys must be pro-
grammed to the SKIM in the vehicle in order for the
system to recognize them as valid keys. This can be
done by the dealer using a DRBIIItscan tool or, if
Customer Learn programming is an available SKIS
feature in the market where the vehicle was pur-
chased, the customer can program the additional
keys, as long as at least two valid Sentry Keys are
already available. (Refer to 8 - ELECTRICAL/VEHI-
CLE THEFT SECURITY - STANDARD PROCE-
DURE - TRANSPONDER PROGRAMMING).
The SKIS performs a self-test each time the igni-
tion switch is turned to the On position, and will
store fault information in the form of DiagnosticTrouble Codes (DTC's) if a system malfunction is
detected. Refer to the appropriate diagnostic informa-
tion.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - VEHICLE THEFT
SECURITY SYSTEM
The VTSS-related hard wired inputs to and out-
puts from the Body Control Module (BCM), the
Driver Door Module (DDM), or the Passenger Door
Module (PDM) may be diagnosed and tested using
conventional diagnostic tools and procedures. Refer
to the appropriate wiring information.
However, conventional diagnostic methods may not
prove conclusive in the diagnosis of the BCM, the
DDM, the PDM, or the Programmable Communica-
tions Interface (PCI) data bus network. In order to
obtain conclusive testing of the VTSS, the BCM, the
DDM, the PDM, and the PCI data bus network must
also be checked. The most reliable, efficient, and
accurate means to diagnose the VTSS requires the
use of a DRBIIItscan tool and the appropriate diag-
nostic information.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
8Q - 4 VEHICLE THEFT SECURITYWJ
VEHICLE THEFT SECURITY (Continued)

factory. The Sentry Key Immobilizer Module (SKIM)
can be programmed to recognize up to a total of eight
Sentry Keys. When programming a blank Sentry Key
transponder, the key must first be cut to match the
ignition switch lock cylinde for which it will be used.
Once the additional key has been cut, the SKIM
must be programmed to recognize it as a valid key.
There are two possible methods to program the
SKIM to recognize a new or additional valid key, the
Secured Access Method and the Customer Learn
Method. Following are the details of these two pro-
gramming methods.
SECURED ACCESS METHOD
The Secured Access method applies to all vehicles.
This method requires the use of a DRBIIItscan tool.
This method will also require that you have access to
the unique four-digit PIN code that was assigned to
the original SKIM. The PIN codemustbe used to
enter the Secured Access Mode in the SKIM. This
PIN number may be obtained from the vehicle owner,
from the original vehicle invoice, or from the
DaimlerChrysler Customer Center. Refer to the
appropriate diagnostic information for the proper
Secured Access method programming procedures.
CUSTOMER LEARN METHOD
The Customer Learn feature is only available on
domestic vehicles, or those vehicles which have a
U.S. country code designator. This programming
method also requires access to at least two valid Sen-
try Keys. If two valid Sentry Keys are not available,
or if the vehicle does not have a U.S. country code
designator, the Secured Access Methodmustbe used
to program new or additional valid keys to the SKIM.
The Customer Learn programming method proce-
dures are as follows:
(1) Obtain the blank Sentry Key(s) that are to be
programmed as valid keys for the vehicle. Cut the
blank key(s) to match the ignition switch lock cylin-
der mechanical key codes.
(2) Insert one of the two valid Sentry Keys into the
ignition switch and turn the ignition switch to the
On position.
(3) After the ignition switch has been in the On
position for longer than three seconds, but no more
than fifteen seconds, cycle the ignition switch back to
the Off position. Replace the first valid Sentry Key in
the ignition switch lock cylinder with the second
valid Sentry Key and turn the ignition switch back to
the On position. The second valid Sentry Key must
be inserted in the lock cylinder within fifteen seconds
of removing the first valid key.
(4) About ten seconds after the completion of Step
3, the SKIS indicator in the instrument cluster will
start to flash and a single audible chime tone willsound to indicate that the system has entered the
Customer Learn programming mode.
(5) Within sixty seconds of entering the Customer
Learn programming mode, turn the ignition switch to
the Off position, replace the valid Sentry Key with a
blank Sentry Key transponder, and turn the ignition
switch back to the On position.
(6) About ten seconds after the completion of Step
5, a single audible chime tone will sound and the
SKIS indicator will stop flashing, stay on solid for
three seconds, then turn off to indicate that the
blank Sentry Key has been successfully programmed.
The SKIS will immediately exit the Customer Learn
programming mode and the vehicle may now be
started using the newly programmed valid Sentry
Key.
Each of these steps must be repeated and com-
pleted in their entirety for each additional Sentry
Key that is to be programmed. If the above steps are
not completed in the given sequence, or within the
allotted time, the SKIS will exit the Customer Learn
programming mode and the programming will be
unsuccessful. The SKIS will also automatically exit
the Customer Learn programming mode if it sees a
non-blank Sentry Key transponder when it should
see a blank, if it has already programmed eight (8)
valid Sentry Keys, or if the ignition switch is turned
to the Off position for more than about fifty seconds.
NOTE: If an attempt is made to start the vehicle
while in the Customer Learn mode (SKIS indicator
flashing), the SKIS will respond as though the vehi-
cle were being started with an invalid key. In other
words, the engine will stall after about two seconds
of operation. No faults will be set.
NOTE: Once a Sentry Key has been programmed as
a valid key to a vehicle, it cannot be programmed
as a valid key for use on any other vehicle.
DOOR CYLINDER LOCK
SWITCH
DESCRIPTION
Vehicles manufactured for North American mar-
kets that are equipped with the optional Vehicle
Theft Security System (VTSS) have a door cylinder
lock switch secured to the back of the key lock cylin-
der inside the drivers front door (Fig. 1). The door
cylinder lock switch is a resistor multiplexed momen-
tary switch that is hard wired in series between the
door lock switch ground and right or left cylinder
lock switch mux circuits of the Drivers Door Module
(DDM) through the front door wire harness. The door
WJVEHICLE THEFT SECURITY 8Q - 7
VEHICLE THEFT SECURITY (Continued)

message inputs to and outputs from the alarm siren
module requires the use of a DRBIIItscan tool.
Refer to the appropriate diagnostic information.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Disconnect the alarm siren module wiring har-
ness connector. (Fig. 9).
(3) Remove the screws that secure the alarm siren
module to the left frame rail.
(4) Remove the alarm siren module.
INSTALLATION
(1) Position the alarm siren module on to the left
frame rail. (Fig. 9).
(2) Install and tighten the screws that secure the
alarm siren moduleto the frame rail. Tighten the
screws to 6 N´m (50 in. lbs.).
(3) Reconnect the alarm siren module wiring har-
ness connector.
(4) Reconnect the battery negative cable.
NOTE: If the alarm siren module has been replaced
with a new unit, the new unit MUST be configured
in the Intrusion Transceiver Module (ITM) before the
Vehicle Theft Security System can operate as
designed. The use of a DRBIIITscan tool is requiredto configure the alarm siren module settings in the
ITM. Refer to the appropriate diagnostic informa-
tion.
SKIS INDICATOR LAMP
DESCRIPTION
A Sentry Key Immobilizer System (SKIS) indicator
lamp is standard equipment on all instrument clus-
ters, but is only functional on vehicles equipped with
the optional SKIS. The amber SKIS indicator lamp is
located to the right of the oil pressure gauge.
OPERATION
The Sentry Key Immobilizer System (SKIS) indica-
tor lamp gives an indication to the vehicle operator of
the status of the SKIS. This lamp is controlled by a
transistor on the instrument cluster circuit board
based upon messages received by the cluster from
the Sentry Key Immobilizer Module (SKIM) over the
Programmable Communications Interface (PCI) data
bus. The SKIS indicator lamp bulb receives battery
current on the instrument cluster circuit board
through the fused ignition switch output (st-run) cir-
cuit whenever the ignition switch is in the On or
Start positions. The lamp bulb only illuminates when
it is provided a path to ground by the instrument
cluster transistor. The instrument cluster will turn
on the SKIS indicator lamp for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position, the SKIM tells the cluster
to illuminate the lamp for about three seconds.
²SKIS Lamp-On Message- Each time the clus-
ter receives a SKIS lamp-on message from the SKIM,
the lamp will be illuminated. The lamp can be
flashed on and off, or illuminated solid, as dictated
by the message from the SKIM. For more informa-
tion on the SKIS and the SKIS lamp control param-
eters, (Refer to 8 - ELECTRICAL/VEHICLE THEFT
SECURITY - OPERATION - SENTRY KEY IMMO-
BILIZER SYSTEM). The lamp remains illuminated
until the cluster receives a lamp-off message from
the SKIM or until the ignition switch is turned to the
Off position, whichever occurs first.
²Actuator Test- Each time the cluster is put
through the actuator test, the lamp will be turned on
for the duration of the test to confirm the functional-
ity of the lamp and the cluster.
The SKIM performs a self-test each time the igni-
tion switch is turned to the On position to decide
whether the system is in good operating condition.
The SKIM then sends a message to the instrument
cluster. If the SKIS indicator lamp fails to light dur-
ing the bulb test, replace the bulb. For further diag-
nosis of the SKIS indicator lamp or the instrument
Fig. 9 Siren Remove/Install
1 - SIREN
2 - FRAME
8Q - 14 VEHICLE THEFT SECURITYWJ
SIREN (Continued)

(4) Reinstall the washer hoses for the front washer
nozzle(s) into their routing clips on the underside of
the cowl grille cover.
(5) Position the cowl grille cover onto the cowl ple-
num and cowl top panels through the opening
between the hood and the base of the windshield
(Fig. 4).
(6) Lift the left end of the cowl grille cover off of
the cowl plenum panel far enough to access the front
washer plumbing.
(7) Reconnect the cowl grille cover washer hose to
the engine compartment washer hose at the elbow
connector.
(8) Install the six plastic nuts that secure the cowl
grille cover to the studs on the cowl top panel near
the base of the windshield. These nuts are to be
installed by pushing them onto the studs in the fol-
lowing sequence:
(a) First, install the short nuts to the third stud
from the right, then the second stud from the left.
(b) Next, install the long nuts to the right out-
board stud, then the left outboard stud.
(c) Finally, install the two remaining long nuts
to the third stud from the left, then the second
stud from the right.
(9) Starting at the ends and working toward the
center, push the hood to plenum seal onto the for-
ward flanges of the cowl grille cover and the plenum
panel.
(10) Close and latch the hood.
(11) Reinstall the wiper arms onto the wiper piv-
ots. (Refer to 8 - ELECTRICAL/FRONT WIPERS/
WASHERS/FRONT WIPER ARMS -
INSTALLATION).
(12) Reconnect the battery negative cable.
FRONT WASHER PUMP/
MOTOR
DESCRIPTION
The front washer pump/motor unit is located on
the outboard side and near the front of the washer
reservoir, between the left front inner and outer
fender panels (Fig. 5). A small permanently lubri-
cated and sealed electric motor is coupled to the
rotor-type washer pump. A seal flange with a large
barbed inlet nipple on the pump housing passes
through a rubber grommet seal installed in one of
two dedicated mounting holes near the bottom of the
washer reservoir. The front washer pump/motor unit
is always mounted in the lower pump mounting hole
of the reservoir. A smaller barbed outlet nipple on the
pump housing connects the unit to the front washer
hose. The washer pump/motor unit is retained on the
reservoir by the interference fit between the barbedpump inlet nipple and the grommet seal, which is a
light press fit. An integral electrical connector recep-
tacle is located on the top of the motor housing. The
front washer pump/motor unit cannot be repaired. If
faulty or damaged, the entire washer pump/motor
unit must be replaced.
OPERATION
The front washer pump/motor unit is connected to
the vehicle electrical system through a single take
out and two-cavity connector of the left headlamp
and dash wire harness. The washer pump/motor is
grounded at all times through a take out of the left
headlamp and dash wire harness with a single eyelet
terminal connector that is secured under a ground
screw to the top of the left inner fender shield in the
engine compartment. The front washer pump/motor
receives battery current on a fused ignition switch
output (run-acc) circuit through the closed contacts of
the momentary front washer switch within the right
multi-function switch only when the switch control
stalk is pulled towards the steering wheel. Washer
fluid is gravity-fed from the washer reservoir to the
inlet side of the washer pump. When the pump motor
is energized, the rotor-type pump pressurizes the
washer fluid and forces it through the pump outlet
nipple, the front washer plumbing, and the front
washer nozzles onto the windshield glass.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
Fig. 5 Washer Pumps (Viewed from Bottom of
Reservoir)
1 - REAR WASHER PUMP/MOTOR
2 - FRONT WASHER PUMP/MOTOR
3 - WASHER FLUID LEVEL SWITCH
8R - 12 FRONT WIPERS/WASHERSWJ
FRONT WASHER NOZZLE (Continued)

(9) Install the six plastic nuts that secure the cowl
grille cover to the studs on the cowl top panel near
the base of the windshield. These nuts are to be
installed by pushing them onto the studs in the fol-
lowing sequence:
(a) First, install the short nuts to the third stud
from the right, then the second stud from the left.
(b) Next, install long nuts to the right outboard
stud, then the left outboard stud.
(c) Finally, install the two remaining long nuts
to the third stud from the left, then the second
stud from the right.
(10) Starting at the ends and working toward the
center, push the hood to plenum seal onto the for-
ward flanges of the cowl grille cover and the plenum
panel.
(11) Close and latch the hood.
(12) Reinstall the wiper arms onto the wiper piv-
ots. (Refer to 8 - ELECTRICAL/FRONT WIPERS/
WASHERS/FRONT WIPER ARMS -
INSTALLATION).
(13) Reconnect the battery negative cable.
RAIN SENSOR MODULE
DESCRIPTION
The Rain Sensor Module (RSM) is the primary
component of the automatic wiper system (Fig. 14).
The RSM is located on the inside of the windshield,
between the rear view mirror mounting button and
the windshield header and is concealed behind a
molded plastic trim cover that snaps over the modulehousing. The triangular-shaped molded black plastic
housing of the RSM has a rectangular opening
located on the upper end of the housing for the mod-
ule connector receptacle, which contains four termi-
nal pins. These terminal pins connect the rain sensor
to the vehicle electrical system through a dedicated
take out and connector of the overhead wire harness
that extends from above the headliner. Five openings
on the windshield side of the RSM housing are fitted
with eight convex clear plastic lenses. A metal spring
clip on each side of the housing near the bottom
secures the RSM to a plastic mounting bracket that
is bonded to the windshield glass. Concealed within
the RSM housing is the electronic circuitry of the
module, which includes four InfraRed (IR) diodes,
two photocells, and a microprocessor.
The RSM software is Flash compatible, which
means it can be reprogrammed using Flash repro-
gramming procedures. However, if any of the hard-
ware of the RSM is damaged or faulty, the entire
module must be replaced. The RSM bracket is ser-
viced as a unit with the windshield glass. If the
bracket is faulty, damaged, or separated from the
windshield glass, the windshield unit must be
replaced.
OPERATION
The microprocessor-based Rain Sensor Module
(RSM) senses moisture in the wipe pattern on the
outside of the windshield glass and sends wipe com-
mands to the Body Control Module (BCM). Four
InfraRed (IR) diodes within the RSM generate IR
light beams that are aimed by four of the convex
optical lenses near the base of the module through
the windshield glass. Four additional convex optical
lenses near the top of the RSM are focused on the IR
light beams on the outside of the windshield glass
and allow the two photocells within the module to
sense changes in the intensity of these IR light
beams. When sufficient moisture accumulates within
the wipe pattern of the windshield glass, the RSM
detects a change in the monitored IR light beam
intensity.
The internal programming of the RSM then sends
the appropriate electronic wipe command messages
to the BCM over the Programmable Communications
Interface (PCI) data bus. The BCM responds by acti-
vating or deactivating the front wiper system. The
BCM also sends electronic sensitivity level messages
to the RSM over the PCI data bus based upon the
driver-selected sensitivity setting of the control knob
on the control stalk of the right (wiper) multi-func-
tion switch. The higher the selected sensitivity set-
ting the more sensitive the RSM is to the
accumulated moisture on the windshield glass, and
Fig. 14 Rain Sensor Module
1 - SPRING CLIP (2)
2 - INFRARED LENS (4)
3 - HOUSING
4 - CONNECTOR RECEPTACLE
5 - PHOTOCELL LENS (4)
8R - 18 FRONT WIPERS/WASHERSWJ
FRONT WIPER MODULE (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)