2004 CHRYSLER VOYAGER engine

Transmitter and the EVIC module are inoperative,
refer toElectronic Vehicle Information Center
Diagnosis and Testingin this group for further
diagnosis. For complete circuit diagrams, refer to
Wiring Diagrams. (Fig. 5) as described below:
(1) Turn the Radio Frequency (RF) Detector ON. A
ªchirpº will sound and the green power LED will
light. If the green LED does not light, replace the
battery.
(2) Hold the RF detector within one inch of the
TRAINED universal transmitter and press any of the
transmitters buttons.
(3) The red signal detection LEDs will light and
the tool will beep if a radio signal is detected. Repeat
this test three times.
STANDARD PROCEDURE
STANDARD PROCEDURE - SETTING
TRANSMITTER CODES
(1) Turn off the engine.
(2) Erase the codes by pressing the two outside
buttons. Release the buttons when the display con-
firms the operation (about 20 seconds).
(3) Choose one of the three buttons to train. Place
the hand-held transmitter within one inch of the uni-
versal transmitter and push the buttons on both
transmitters.(4) Release both buttons. Your universal transmit-
ter is now ªtrainedº. To train the other buttons,
repeat Step 3 and Step 4. Be sure to keep your hand-
held transmitter in case you need to retrain the uni-
versal transmitter.
STANDARD PROCEDURE - ERASING
TRANSMITTER CODES
To erase the universal transmitter codes, simply
hold down the two outside buttons until the display
confirms the operation.
NOTE: Individual channels cannot be erased. Eras-
ing the transmitter codes will erase ALL pro-
grammed codes.
REMOVAL
(1) For universal transmitter removal and installa-
tion procedure, (Refer to 8 - ELECTRICAL/OVER-
HEAD CONSOLE/COMPASS/MINI-TRIP
COMPUTER - REMOVAL and INSTALLATION).
AMBIENT TEMP SENSOR
DESCRIPTION
Ambient air temperature is monitored by the over-
head console through ambient temperature messages
received from the Front Control Module (FCM) over
the Programmable Communications Interface (PCI)
J1850 data bus circuit. The FCM receives a hard
wired input from the ambient temperature sensor.
The ambient temperature sensor is a variable resis-
tor mounted to a bracket that is secured with a screw
to the right side of the headlamp mounting module
grille opening, behind the radiator grille and in front
of the engine compartment.
For more information on the Front Control Module
refer to the Electronic Control Modules section of this
manual. For complete circuit diagrams, refer to the
appropriate wiring information. The ambient temper-
ature sensor cannot be adjusted or repaired and, if
faulty or damaged, it must be replaced.
OPERATION
The ambient temperature sensor is a variable
resistor that operates on a five-volt reference signal
sent to it by the Front Control Module. The resis-
tance in the sensor changes as temperature changes,
changing the temperature sensor signal circuit volt-
age to the Front Control Module. Based upon the
resistance in the sensor, the Front Control Module
senses a specific voltage on the temperature sensor
signal circuit, which it is programmed to correspond
to a specific temperature. The Front Control Module
Fig. 5 RADIO FREQUENCY DETECTOR
1 - SIGNAL DETECTION LED'S
2 - POWER LED
3 - ON/OFF SWITCH
4 - 9V BATTERY
RSMESSAGE SYSTEMS8M-11
UNIVERSAL TRANSMITTER (Continued)

POWER LOCKS
TABLE OF CONTENTS
page page
POWER LOCKS
DESCRIPTION.........................38
OPERATION...........................39
DOOR CYLINDER LOCK SWITCH
DESCRIPTION.........................40
OPERATION...........................40
DIAGNOSIS AND TESTING - DOOR
CYLINDER LOCK SWITCH..............40
REMOVAL.............................41
INSTALLATION.........................41
DOOR LOCK MOTOR
DIAGNOSIS AND TESTING - DOOR LOCK
MOTOR .............................41
DOOR LOCK SWITCH
DIAGNOSIS AND TESTING - DOOR LOCK
SWITCH............................41
REMOVAL.............................42
INSTALLATION.........................42
KEYLESS ENTRY TRANSMITTER
DIAGNOSIS AND TESTING - KEYLESS ENTRY
TRANSMITTER.......................42STANDARD PROCEDURE
STANDARD PROCEDURE - HORN CHIRP
PREFERENCE........................42
STANDARD PROCEDURE - BATTERY
REPLACEMENT.......................42
STANDARD PROCEDURE - RKE
TRANSMITTER PROGRAMING...........43
SPECIFICATIONS
RANGE.............................43
BATTERY...........................43
REMOTE KEYLESS ENTRY MODULE
DESCRIPTION.........................43
OPERATION...........................43
DIAGNOSIS AND TESTING - REMOTE
KEYLESS ENTRY MODULE..............43
REMOVAL.............................44
INSTALLATION.........................44
SLIDING DOOR LOCK MOTOR
REMOVAL.............................44
INSTALLATION.........................44
POWER LOCKS
DESCRIPTION
POWER DOOR LOCK SYSTEM
The front doors, sliding door(s) and liftgate are
equipped with actuator motors to lock or unlock the
latch mechanisms. The door lock actuator motor is
not serviced separately from the door latch, except
for the sliding door(s).
AUTOMATIC DOOR LOCK
The vehicle comes with two options for power door
locks:
²Rolling automatic lock (ENABLE), doors auto-
matically lock at approximately at 25.7 Km/h (16
mph).
²No rolling automatic lock (DISABLE), doors do
not automatically lock when the vehicle is moving.
AUTOMATIC DOOR UNLOCK
The doors will unlock automatically on vehicles
equipped with power door locks if:
²Auto door locks feature is enabled and automatic
unlock is enabled.²The transmission was in gear and speed was
above zero.
²The transmission in park or neutral and speed
is zero.
²Any door (excluding liftgate) opens.
DOOR LOCK INHIBIT
The BCM cancels out the door lock switch actua-
tion, when the key is in the Ignition Switch and
either front door is open.
Pressing the key fob RKE lock/unlock under these
conditions results in normal lock/unlock activation.
CENTRAL LOCKING
If equipped with Vehicle Theft Security System
(VTSS), all the doors can be locked with the key by
using the driver door lock cylinder. Turning the key
to the lock position will lock all the doors.
DOOR LOCK CIRCUIT PROTECTION
The door lock system is protected by a 40 amp fuse
located in the IPM. The BCM receives lock/unlock
input and will turn on the appropriate drivers and
provide a voltage level to the door lock motor for a
specific time. The IPM is located along the side of the
vehicle battery in the engine compartment.
8N - 38 POWER LOCKSRS

STANDARD PROCEDURE - RKE TRANSMITTER
PROGRAMING
(1) Using a functional key fob transmitter, unlock
the vehicle and disarm the Vehicle Theft Security
System.
(2) Insert ignition key into the ignition switch.
(3) Turn the ignition switch to RUN position with-
out starting engine.
(4) Using a functional key fob transmitter, press
and hold the UNLOCK button for a minimum five
seconds (maximum ten seconds).
(5) While still holding UNLOCK button, and
before ten seconds passes, press the PANIC button
and release both at the same time. A single chime
will sound to indicate that the transmitter program-
ming mode has been entered (allow 3 seconds for
chime to sound).
(6) Within 30 seconds of the chime, press and
release the ªLOCKº and ªUNLOCKº buttons on the
transmitter at the same time. Then press and release
any button on the same transmitter and a chime will
sound after successfully programming the transmit-
ter.
(7) Repeat steps 5 and 6 for all transmitters that
will be used with this vehicle (up to 4 total).
(8) Turn ignition to the OFF position. Transmitter
programming mode will discontinue after 60 seconds.
All transmitter programming must be com-
pleted within time specified.
SPECIFICATIONS
RANGE
Normal operation range is up to a distance of 7
meters (23 ft.) of the vehicle. Range may be better or
worse depending on the environment around the
vehicle. Closeness to a radio frequency transmitter
such as a radio station tower that is broadcasting on
105 MHz FM or a 156 MHz 2±way communication
station, may degrade operational range, while range
in an open field will be enhanced.
BATTERY
The batteries can be removed without special tools
and are readily available at local retail stores. Therecommended battery is Duracell DL 2016 or equiva-
lent, TWO cells are required. Battery life is about
three years minimum.
CAUTION: Do not touch the battery terminals or
handle the batteries any more than necessary.
Hands must be clean and dry.
REMOTE KEYLESS ENTRY
MODULE
DESCRIPTION
The RKE module is capable of retaining up to four
different Vehicle Access Codes.
OPERATION
Whenever the vehicle battery power is interrupted
the RKE Module will retain all vehicle access codes
in its memory. When replacing or adding a key fob
transmitter (maximum 4) a DRB IIItscan tool is
required to program the RKE Module to accept the
new Vehicle Access Code if a customer owned trans-
mitter is not available. Refer to Electrical, Remote
Keyless Entry Module, Standard Procedure - Pro-
gramming RKE Module or the Proper Body Diagnos-
tic Procedures manual.
DIAGNOSIS AND TESTING - REMOTE KEYLESS
ENTRY MODULE
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, further details
on wire harness routing and retention, as well as
pin-out and location views for the various wire har-
ness connectors, splices and grounds. Refer to the
proper Body Diagnostic Procedures Manual for test-
ing the Remote Keyless Entry system using a
DRB IIItscan tool. Also refer to other interrelated
systems groups within this manual:
²Vehicle Theft Security System
²Power Seats
²Power Mirrors
RSPOWER LOCKS8N-43
KEYLESS ENTRY TRANSMITTER (Continued)

NOTE: Turning the system off by depressing the
OFF switch or turning off the ignition switch will
erase the set speed stored in the PCM.
For added safety, the speed control system is pro-
grammed to disengage for any of the following condi-
tions:
²An indication of Park or Neutral
²A rapid increase rpm (indicates that the clutch
has been disengaged)
²Excessive engine rpm (indicates that the trans-
mission may be in a low gear)
²The speed signal increases at a rate of 10 mph
per second (indicates that the co-efficient of friction
between the road surface and tires is extremely low)
²The speed signal decreases at a rate of 10 mph
per second (indicates that the vehicle may have
decelerated at an extremely high rate)
²If the actual speed is greater than 20 mph over
the set speed.
²Autostick shifts into 1st or 2nd gear (autostick,
if equipped)
Once the speed control has been disengaged,
depressing the RESUME switch when speed is
greater than 20 mph allows the vehicle to resume
control to the target speed that was stored in the
PCM.
While the speed control is engaged, the driver can
increase the vehicle speed by depressing the ACCEL
switch. The new target speed is stored in the PCM
when the ACCEL switch is released. The PCM also
has a9tap-up9feature in which target speed
increases by 2 mph for each momentary switch acti-
vation of the ACCEL switch. The PCM also provides
a means to decelerate to a new lower target speed
without disengaging speed control. Depress and hold
the COAST switch until the desired speed is reached,
then release the switch.
The PCM also has a ªTap Downº feature in which
target speed decreases at 1 mph for each momentary
switch activation of the coast switch.
OPERATION - INTERACTIVE SPEED CONTROL
(4 Speed EATX Only)
Interactive means that communication between the
PCM and the TCM is taking place, this communica-
tion is internal to the PCM on NGC vehicles. Inter-
active speed control avoids unnecessary shifting for
smoother, quieter operation and when downshifts are
required, makes the shifts smoother.
CLIMBING A GRADE
DESCRIPTION
When climbing a grade the interactive speed con-
trol tries to maintain the set speed by increasing the
throttle opening, while inhibiting/delaying down-
shifts.
OPERATION
If opening the throttle alone cannot maintain the
set speed and the vehicle speed drops more than
three mph below the set speed, the transmission will
downshift to third gear. If the vehicle continues to
lose speed, by more than 6 mph, the transmission
will downshift again to maintain the set speed. After
the vehicle encounters a less-steep grade, or has
crested the grade (reduced the load on the power-
train) and can maintain the set speed at a reduced
throttle position, the transmission will upshift, as
appropriate, until the set speed can be maintained in
Overdrive.
GRADE HUNTING
DESCRIPTION
All vehicles equipped with a four speed automatic
transmission have a grade hunting feature for the
2nd to 3rd gear upshift and the 3rd to Overdrive
upshift.
OPERATION
The TCM (on SBEC vehicles) (PCM on NGC vehi-
cles) identifies the powertrain loading conditions and
selects the proper gear to maintain the current vehi-
cle speed. Under moderate loading conditions the
transaxle will stay in 3rd gear until the top of the
grade is reached or the powertrain loading is
reduced.
If powertrain loading is severe, the transaxle may
shift into 2nd gear and remain there until power-
train loading is reduced, then a 2nd to 3rd gear
upshift will be scheduled. Grade hunting features
always operate regardless of whether or not the
interactive speed control is engaged.If the interac-
tive speed control is not engaged and power-
train loading is not reduced, the driver may
have to completely lift off of the throttle before
an upshift will occur. If the driver does lift off the
throttle to induce an upshift under these conditions,
vehicle speed will reduce and the Overdrive to 3rd
and 3rd to 2nd gear downshifts will reoccur when the
throttle is reapplied. If grade hunting is repeatedly
induced by the driver, transaxle damage may result.
8P - 2 SPEED CONTROLRS
SPEED CONTROL (Continued)

SWITCH
DESCRIPTION
There are two separate switch pods that operate
the speed control system and are located on the
steering wheel.
OPERATION
The speed control system has five separate resis-
tive switches that provide a single multiplexed
(MUX) voltage inputs to the PCM.The switch names
are: ON, OFF, SET, COAST, RESUME, ACCEL, TAP-
UP, COAST, and CANCEL. Based on conditions when
the buttons are pushed (and released), the five volt-
ages ranges provided to the PCM result in the follow-
ing functions: ON, OFF, SET, COAST, RESUME,
ACCEL, TAP-UP, TAP-DOWN, COAST, and CAN-
CEL. Refer to the Speed Control Section for more
information
Also the PCM receives an input from the brake
switch to sense whether the brake pedal has been
depressed. When the PCM receives the brake
depressed input, it turns off power to the speed con-
trol servo and disengages speed control. Also the
power to the servo is supplied through the brake
switch, which opens the circuit when the brake pedal
is depressed.
The individual switches cannot be repaired. If one
switch fails, the entire switch module must be
replaced.
REMOVAL
The speed control switches are mounted in the
steering wheel and wired through the clock spring
device under the airbag module.
WARNING: IF REMOVAL OF AIRBAG MODULE IS
NECESSARY, REFER TO THE RESTRAINT SYS-
TEMS SECTION FOR MORE INFORMATION.
(1) Remove the negative battery cable.
(2) Turn off ignition.
(3) Remove the air bag, refer to the restraint sec-
tion for more information.
(4) Remove the screw from bottom of the switch.
(5) Remove switch from steering wheel.
(6) Disconnect two-way electrical connector.
(7) Repeat for the other switch.
INSTALLATION
The speed control switches are mounted in the
steering wheel and wired through the clock spring
device under the airbag module.WARNING: IF REMOVAL OF AIRBAG MODULE IS
NECESSARY, REFER TO THE RESTRAINT SYS-
TEMS SECTION FOR MORE INFORMATION.
(1) Connect two-way electrical connector.
(2) Install switch.
(3) Install screw for the switch.
(4) Repeat for the other switch.
(5) Install the air bag, refer to the restraint section
for more information.
(6) Install the negative battery cable.
VACUUM RESERVOIR
DESCRIPTION
The vacuum reservoir is located in the engine com-
partment. It is made of plastic.
OPERATION
The reservoir stores engine vacuum. Manifold vac-
uum is supplied from the brake booster check valve.
The speed control vacuum supply hose has a check
valve at the source (brake booster) to maintain the
highest available vacuum level in the servo, reservoir
and vacuum hoses. When engine vacuum drops, as in
climbing a grade while driving, the reservoir supplies
the vacuum needed to maintain proper speed control
operation. The vacuum reservoir cannot be repaired
and must be replaced if faulty.
REMOVAL
(1) Release hood latch and open hood.
(2) Disconnect the negative battery cable.
(3) Disconnect the vacuum line to the battery tray/
vacuum reservoir.
(4) Remove battery tray/vacuum reservoir, refer to
the Battery section for more information.
INSTALLATION
(1) Install battery tray/vacuum reservoir, refer to
the Battery section for more information.
(2) Connect vacuum line that leads to the battery
tray/vacuum reservoir.
(3) Connect the negative battery cable.
8P - 6 SPEED CONTROLRS

VEHICLE THEFT SECURITY
TABLE OF CONTENTS
page page
VEHICLE THEFT SECURITY
DESCRIPTION..........................1
OPERATION............................1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - SENTRY KEY
REMOTE ENTRY SYSTEM...............3
DIAGNOSIS AND TESTING - VEHICLE
THEFT SECURITY SYSTEM..............3
HOOD AJAR SWITCH - EXPORT
REMOVAL.............................3
INSTALLATION..........................3
SENTRY KEY REMOTE ENTRY MODULE
DESCRIPTION..........................3OPERATION............................4
DIAGNOSIS AND TESTING - SENTRY KEY
REMOTE ENTRY MODULE...............5
REMOVAL.............................5
INSTALLATION..........................6
TRANSPONDER KEY
DESCRIPTION..........................6
OPERATION............................6
STANDARD PROCEDURE - TRANSPONDER
PROGRAMMING.......................6
VTSS/SKIS INDICATOR LAMP
DESCRIPTION..........................7
OPERATION............................8
VEHICLE THEFT SECURITY
DESCRIPTION
VEHICLE THEFT SECURITY SYSTEM
The Vehicle Theft Security System (VTSS) is
designed to protect against whole vehicle theft. The
system monitors vehicle doors, and ignition action for
unauthorized operation (hood and liftgate for RG -
Export). The alarm activates:
²Sounding of the horn
²Flashing of the headlamps/park/tail lamps
²Flashing of the headlamps
²An engine kill feature (with SKREES)
SENTRY KEY REMOTE ENTRY SYSTEM
The Sentry Key Remote Entry System (SKREES)
is available as a factory-installed option on this vehi-
cle. It is designed to provide passive protection
against unauthorized vehicle use by disabling the
engine, after two (2) seconds of running, whenever an
invalid key is used to start the vehicle. The SKIS is
active whenever the ignition is on and does not
require any customer intervention. The primary com-
ponents of the system are the Sentry Key Remote
Entry Module (SKREEM), Sentry Key (ignition key
with a transponder molded into the head), indicator
light, Body Control Module (BCM), and the Power-
train Control Module (PCM). The SKREEM is
mounted to the steering column with the molded,
integral antenna mounted on the ignition housing.
The indicator light, is located in the Mechanical
Instrument Cluster (MIC).
OPERATION
VEHICLE THEFT SECURITY SYSTEM
Upon failure of proper Sentry Key Remote Entry
Module (SKREEM) communication to the PCM, the
PCM will shut off fuel after two seconds of run time.
The engine will not re-crank on the key cycle that
the failure occurred, a full key down sequence must
be performed for the engine to crank again. After six
consecutive fuel shut-offs, the engine will no longer
crank on subsequent key cycles. The failure must be
corrected and a valid communication process between
the SKREEM and the PCM must occur for the
engine to crank and start again.
The electronics for the VTSS are part of the Body
Control Module (BCM). The system is armed when
the vehicle is locked using the:
²Power door lock switches (with any door ajar)
²Remote Keyless Entry transmitter.
²Door Cylinder Lock Switches (RG only).
For vehicles equipped with Sentry Key Remote
Entry System (SKREES), the doors do not have to be
locked to enable the fuel shut off feature.
After the vehicle is locked and the last door is
closed, the set LED indicator in the Mechanical
Instrument Cluster (MIC) will flash quickly for 16
seconds, indicating that arming is in progress. If no
monitored systems are activated during this period,
the system will arm. The LED will extinguish unless
the liftgate is open. If the liftgate is open, the LED
will flash at a slower rate. This indicates that the
system is armed.
RG Only- If fault is detected on the driver key
cylinder input, the indicator LED will remain solid
RSVEHICLE THEFT SECURITY8Q-1

during the arming process, although the system will
still arm.
If the indicator LED does not illuminate at all
upon door closing it indicates that the system is not
arming.
Passive disarming occurs upon normal vehicle
entry by unlocking either door with the remote trans-
mitter (RG - ignition key or remote transmitter). This
disarming will also halt the alarm once it has been
activated.
A tamper alert exists to notify the driver that the
VTSS had been activated. This alert consists of 3
horn pulses when the vehicle is disarmed.
NOTE: The VTSS will not arm by pushing down the
door lock mechanism. This will manually override
the system.
RG Only- For Door Cylinder Lock Switch
Removal and Installation, refer to Electrical, Power
Locks, Door Cylinder Lock Switch.
If the VTSS is triggered, the horn will pulse, head-
lamps/marker lamps will flash, and the VTSS warn-
ing lamp will flash. If BCM determines the threat to
be false and the VTSS is not triggered again, the sys-
tem will shut down and rearm itself after three min-
utes. If a trigger is still active, the alarm will
continue for an additional 15 minutes without the
horn. The VTSS monitors the passenger compart-
ment (for RG - Export it also monitors the engine
compartment. If a malfunction occurs in the engine
compartment, the passenger compartment would still
arm and function normally).
NOTE: System will not arm if passenger compart-
ment is not secure.
NOTE: (RG - Export - If hood is not secure during
the arming sequence, the lamp will stay lit and not
flash. The system will arm with hood not secured
and the liftgate open).
ARMING THE VTSS - METHOD A
(1) With the key removed from the ignition lock
and any door open (excluding liftgate), actuate one of
the following:
²Power door lock button to LOCK,
²Key fob LOCK button
²Driver door lock key cylinder to locked position
(RG Only).
(2) Close all opened doors. Liftgate can remain
open.
(3) After the last door is closed, an arming time-
out period of sixteen seconds will start, then the
VTSS will become armed.
ARMING THE VTSS - METHOD B
Actuating the key fob transmitter LOCK button,
key locking the front doors with the doors closed and
the ignition locked will begin the arming time-out
period. If method A, 16 second time-out sequence was
in process when method B was actuated, the 16 sec-
ond time-out will restart from the time of the second
actuation.
If the security lamp does not illuminate at all upon
final door closure, it indicates that the system is not
arming.
The current VTSS status armed or disarmed shall
be maintained in memory to prevent battery discon-
nects from disarming the system.
TRIGGERING THE VTSS
After the VTSS is armed, the following actions will
trigger the alarm:
²Opening any door (liftgate - only if opening via
liftgate button on key fob).
²Opening the hood (RG - Export)
²Turning the ignition to the RUN position.
NOTE: When the VTSS is ARMED, the interior
power door lock switch ªUNLOCKº will be disabled
until the vehicle is disarmed.
CAUTION: The VTSS indicator LED will trigger and
engine will continue to run if the vehicle is
equipped with SKREES and the proper key is used
to start the vehicle. This condition will occur if the
VTSS has been triggered. If valid key is used, VTSS
will disarm
SENTRY KEY REMOTE ENTRY SYSTEM
The SKREES includes keys from the factory which
are pre-programmed. Each SKREEM will recognize a
maximum of eight Sentry Keys. If the customer
would like to own additional keys other than those
provided with the vehicle, they can be purchased
from any authorized dealer. These keys must be pro-
grammed to the SKREEM on the vehicle in order for
the system to recognize them as valid keys. This can
be done by the dealer with a DRBllltscan tool or by
a customer if this feature is available in their market
and they have two (2) valid keys already available to
them. Refer to the Service Procedures portion of this
system for additional details. The SKREES performs
a self-test each time the ignition switch is turned to
the ON position and will store Diagnostic Trouble
Codes (DTC's) if a system malfunction is detected.
The SKREES can be diagnosed and any stored DTC's
can be retrieved using a DRBllltscan tool as
described in the appropriate Body Diagnostic Proce-
dures information.
8Q - 2 VEHICLE THEFT SECURITYRS
VEHICLE THEFT SECURITY (Continued)

message must be sent to the Powertrain Control
Module (PCM) within two seconds of ignition ON to
free the engine from immobilization.
The SKREEM contains a Radio Frequency (RF)
transceiver and a microprocessor. The SKREEM
retains in memory the ID numbers of any Sentry Key
that is programmed to it. The maximum number of
keys that may be programmed to each module is
eight (8). The SKREEM also communicates over the
Programmable Communication Interface (PCI) data
bus with the Powertrain Control Module (PCM), the
Body Control Module (BCM), the Mechanical Instru-
ment Cluster (MIC), and the DRB IIItscan tool. The
SKREEM transmits and receives RF signals through
a tuned antenna enclosed within a molded plastic
ring formation that is integral to the SKREEM hous-
ing. When the SKREEM is properly installed on the
steering column, the antenna ring fits snugly around
the circumference of the ignition lock cylinder hous-
ing. If this ring is not mounted properly, communica-
tion problems may arise in the form of transponder-
related faults.
For added system security, each SKREEM is pro-
grammed with a unique9Secret Key9code. This code
is stored in memory and is sent over the PCI bus to
the PCM and to each key that is programmed to
work with the vehicle. The9Secret Key9code is there-
fore a common element found in all components of
the Sentry Key Immobilizer System (SKIS). In the
event that a SKREEM replacement is required, the
9Secret Key9code can be restored from the PCM by
following the SKIM replacement procedure found in
the DRB IIItscan tool. Proper completion of this
task will allow the existing ignition keys to be repro-
grammed. Therefore, new keys will NOT be needed.
In the event that the original9Secret Key9code can
not be recovered, new ignition keys will be required.
The DRB IIItscan tool will alert the technician if
key replacement is necessary. Another security code,
called a PIN, is used to gain secured access to the
SKREEM for service. The SKREEM also stores in its
memory the Vehicle Identification Number (VIN),
which it learns through a bus message from the
assembly plant tester. The SKIS scrambles the infor-
mation that is communicated between its components
in order to reduce the possibility of unauthorized
SKREEM access and/or disabling.
REMOTE KEYLESS ENTRY (RKE)
The RKE transmitter uses radio frequency signals
to communicate with the SKREEM. The SKREEM is
on the PCI bus. When the operator presses a button
on the transmitter, it sends a specific request to the
SKREEM. In turn the SKREEM sends the appropri-
ate request over the PCI Bus to the:²Body Control Module (BCM) to control the door
lock and unlock functions, the liftgate lock and
unlock functions, the arming and disarming of the
Vehicle Theft Security System (VTSS) (if equipped),
and the activation of illuminated entry.
²Integrated Power Module (IPM) to activate the
park lamps, the headlamps, and the horn for horn
chirp. If requested, the BCM sends a request over
the PCI Bus to the:
TIRE PRESSURE MONITORING (TPM)
If equipped with the Tire Pressure Monitoring
(TPM) System, each of the vehicles four wheels will
have a valve stem with a pressure sensor and radio
transmitter built in. Signals from the tire pressure
sensor/transmitter are received and interpreted by
the SKREEM.
A sensor/transmitter in a mounted wheel will
broadcast its detected pressure once per minute
when the vehicle is moving faster than 15 mph (24
km/h). Each sensor/transmitter's broadcast is
uniquely coded so that the SKREEM can determine
the location.
OPERATION
SENTRY KEY IMMOBILIZER
The Sentry Key Remote Entry Module (SKREEM)
receives an encrypted Radio Frequency (RF) signal
from the transponder key. The SKREEM then
decrypts the signal and broadcasts the requested
remote commands to the appropriate modules in the
vehicle over the Programmable Communication
Interface (PCI) data bus. A valid transponder key ID
must be incorporated into the RF signal in order for
the SKREEM to pass the message on to the appro-
priate modules.
Automatic transponder key synchronization is done
by the SKREEM if a valid transponder key is
inserted into the ignition cylinder, and the ignition is
turned ON. This provides a maximum operation win-
dow for RKE functions.
Each Sentry Key Remote Entry System (SKREES)
consists of a SKREEM and a transponder key. Each
system has a secret key code unique to that system.
The secret key is electronically coded in the
SKREEM and in all programmed transponder keys.
It is used for immobilization and RKE functions for
data security. In addition, each transponder key will
have a unique identification.
When the ignition switch is moved to the RUN
position, the SKREEM transmits an Radio Frequency
(RF) signal to the transponder in the ignition key.
The SKREEM then waits for a response RF signal
from the transponder in the key. If the response
received identifies the key as valid, the SKREEM
8Q - 4 VEHICLE THEFT SECURITYRS
SENTRY KEY REMOTE ENTRY MODULE (Continued)