2004 DODGE TOWN AND COUNTRY turn signal

tioning valve. The EVBP system uses the ABS sys-
tem to control the slip of the rear wheels in partial
braking range. The braking force of the rear wheels
is controlled electronically by using the inlet and out-
let valves located in the integrated control unit
(ICU).
EVBP activation is invisible to the customer since
there is no pump motor noise or brake pedal feed-
back.
DESCRIPTION - TRACTION CONTROL SYSTEM
Traction control reduces wheel slip and maintains
traction at the driving wheels at speeds below 56
km/h (35 mph) when road surfaces are slippery. The
traction control system reduces wheel slip by braking
the wheel that is losing traction.
HYDRAULIC SHUTTLE VALVES
Two pressure relief hydraulic shuttle valves are
included on vehicles with traction control. These
valves are located inside the HCU and cannot be ser-
viced separately from the HCU.
TRACTION CONTROL LAMP
The traction control function lamp is located in the
transmission range indicator display of the instru-
ment cluster, displaying TRAC, TRAC OFF or nei-
ther depending on system mode.
The TRAC OFF lamp is controlled by a Traction
Control Off switch that is a momentary contact type
switch. The Traction Control Off switch is located on
the steering column upper shroud.
OPERATION
OPERATION - ANTILOCK BRAKE SYSTEM
There are a few performance characteristics of the
Mark 20e Antilock Brake System that may at first
seem abnormal, but in fact are normal. These char-
acteristics are described below.
NORMAL BRAKING
Under normal braking conditions, the ABS func-
tions the same as a standard base brake system with
a diagonally split master cylinder and conventional
vacuum assist.
ABS BRAKING
ABS operation is available at all vehicle speeds
above 3±5 mph. If a wheel locking tendency is
detected during a brake application, the brake system
enters the ABS mode. During ABS braking, hydraulic
pressure in the four wheel circuits is modulated to
prevent any wheel from locking. Each wheel circuit is
designed with a set of electric solenoids to allow mod-ulation, although for vehicle stability, both rear wheel
solenoids receive the same electrical signal. Wheel
lockup may be perceived at the very end of an ABS
stop and is considered normal.
During an ABS stop, the brakes hydraulic system
is still diagonally split. However, the brake system
pressure is further split into three control channels.
During antilock operation of the vehicle's brake sys-
tem, the front wheels are controlled independently
and are on two separate control channels, and the
rear wheels of the vehicle are controlled together.
The system can build and release pressure at each
wheel, depending on signals generated by the wheel
speed sensors (WSS) at each wheel and received at
the controller antilock brake (CAB).
NOISE AND BRAKE PEDAL FEEL
During ABS braking, some brake pedal movement
may be felt. In addition, ABS braking will create
ticking, popping, or groaning noises heard by the
driver. This is normal and is due to pressurized fluid
being transferred between the master cylinder and
the brakes. If ABS operation occurs during hard
braking, some pulsation may be felt in the vehicle
body due to fore and aft movement of the suspension
as brake pressures are modulated.
At the end of an ABS stop, ABS is turned off when
the vehicle is slowed to a speed of 3±4 mph. There
may be a slight brake pedal drop anytime that the
ABS is deactivated, such as at the end of the stop
when the vehicle speed is less than 3 mph or during
an ABS stop where ABS is no longer required. These
conditions exist when a vehicle is being stopped on a
road surface with patches of ice, loose gravel, or sand
on it. Also, stopping a vehicle on a bumpy road sur-
face activates ABS because of the wheel hop caused
by the bumps.
TIRE NOISE AND MARKS
Although the ABS system prevents complete wheel
lockup, some wheel slip is desired in order to achieve
optimum braking performance. Wheel slip is defined
as follows: 0 percent slip means the wheel is rolling
freely and 100 percent slip means the wheel is fully
locked. During brake pressure modulation, wheel slip
is allowed to reach up to 25±30 percent. This means
that the wheel rolling velocity is 25±30 percent less
than that of a free rolling wheel at a given vehicle
speed. This slip may result in some tire chirping,
depending on the road surface. This sound should not
be interpreted as total wheel lockup.
Complete wheel lockup normally leaves black tire
marks on dry pavement. The ABS will not leave dark
black tire marks since the wheel never reaches a
fully locked condition. However, tire marks may be
noticeable as light patched marks.
5 - 76 BRAKES - ABSRS
BRAKES - ABS (Continued)

to Step 6. If not OK, repair the open circuit as
required.
(6) Turn the ignition switch to the OFF position.
Check for battery voltage at the fused B(+) circuit
cavity of the radio wire harness connector. If OK,
replace the faulty radio. If not OK, repair the open
circuit to the Ignition-Off Draw (IOD) fuse as
required.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove cup holder.
(3) Remove trim panel above cupholder by pulling
straight out.
(4) Remove center instrument panel trim panel.
(5) Remove screws holding radio to instrument
panel.
(6) Pull radio rearward to gain access to the back
of radio (Fig. 10).
CAUTION: Pulling the antenna cable straight out of
the radio without pulling on the locking antenna
connector could damage the cable or radio.
(7) Disconnect the antenna cable by pulling the
locking antenna connector away from the radio (Fig.
11).
(8) Disconnect the wire connectors from the back
of the radio.
INSTALLATION
(1) Connect wire harness to back of radio.
(2) Connect antenna cable to back of radio.
(3) Position radio into instrument panel.
(4) Install screws holding radio to instrument
panel.(5) Install center instrument panel trim.
(6) Install trim panel above cupholder.
(7) Install cupholder.
(8) Connect battery negative cable.
RADIO NOISE SUPPRESSION
COMPONENTS
DESCRIPTION
Radio noise suppression devices are factory-in-
stalled standard equipment on this vehicle. Radio
Frequency Interference (RFI) and ElectroMagnetic
Interference (EMI) can be produced by any on-board
or external source of electromagnetic energy. These
electromagnetic energy sources can radiate electro-
magnetic signals through the air, or conduct them
through the vehicle electrical system.
When the audio system converts RFI or EMI to an
audible acoustic wave form, it is referred to as radio
noise. This undesirable radio noise is generally man-
ifested in the form of ªbuzzing,º ªhissing,º ªpopping,º
ªclicking,º ªcrackling,º and/or ªwhirringº sounds. In
most cases, RFI and EMI radio noise can be sup-
pressed using a combination of vehicle and compo-
nent grounding, filtering and shielding techniques.
This vehicle is equipped with factory-installed radio
noise suppression devices that were designed to min-
imize exposure to typical sources of RFI and EMI;
thereby, minimizing radio noise complaints.
Factory-installed radio noise suppression is accom-
plished primarily through circuitry or devices that
are integral to the factory-installed radios, audio
power amplifiers and other on-board electrical com-
ponents such as generators, wiper motors, blower
Fig. 10 RADIO
1 - RADIO
2 - CD-PLAYER
Fig. 11 ANTENNA TO RADIO
1 - RADIO
2 - LOCKING ANTENNA CONNECTOR
3 - INSTRUMENT PANEL ANTENNA CABLE
RSAUDIO8A-11
RADIO (Continued)

CHIME/BUZZER
TABLE OF CONTENTS
page page
CHIME/BUZZER
DESCRIPTION..........................1
OPERATION............................1WARNING.............................1
DIAGNOSIS AND TESTING - CHIME SYSTEM . . 1
CHIME/BUZZER
DESCRIPTION
The chime/buzzer system provides the driver with
warning chimes for:
²Seat Belt
²Exterior Lamps ON
²Key-In Ignition
²Engine Temperature Critical
²Turn Signals ON
²Dome Lamp ON
²Low Oil Pressure
²High Speed Warning
²Warning Lamp Announcement
²Key-In Accessory
²Low/High Tire Pressure
²Service Tire Pressure Monitor (TPM)
HIGH SPEED WARNING - EXPORT
The chime will sound, acting as a warning to the
driver that the vehicle speed has exceeded 120   3
kph (75   2 mph).
Refer to the proper Body Diagnostic Procedures
manual for further description of chimes.
OPERATION
Refer to the proper Body Diagnostic Procedures
manual for complete chime/buzzer operation and con-
ditions for operation.
HIGH SPEED WARNING - EXPORT
When the vehicle speed sensor sees 120 3kph
(75   2 mph), it sends a PCI data bus message to the
Body Control Module (BCM). The BCM then turns on
the chime to let the driver know that the vehicle has
reached a speed greater than 120 3kph(75 2
mph). This audible message will continue until the
vehicle is slowed below the predetermined speed.
WARNING
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.
DIAGNOSIS AND TESTING - CHIME SYSTEM
Refer to the proper Body Diagnostic Procedures
manual for complete Diagnosis and Testing of the
Chime System.
NO TONE WHEN IGNITION SWITCH IS TURNED ON
AND DRIVER'S SEAT BELT IS NOT BUCKLED.
(1) Using a DRB llltscan tool, actuate chime
(BCM actuates).
(2) Using a voltmeter, check for voltage:
(a) BCM has two battery feeds at pin 1 and pin
5 of the 6±way connector.
(b) Pin 5 of the (BX2) 32 way connector of the
BCM for ignition feed.
(c) Check voltage (PX2) connector, pin 34 for 12v.
(d) If voltage OK, go to step Step 3
(e) If NO voltage repair as necessary. 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 harness
connectors, splices and grounds.
RSCHIME/BUZZER8B-1

(6) Remove the screws holding the BCM to the
bulkhead.
(7) Remove the BCM from the mounting bracket.
INSTALLATION
(1) Install the BCM to the mounting bracket.
(2) Install the screws holding the BCM to the
bulkhead.
(3) Connect the five wire connectors to the bottom
of the Body Control Module (BCM).
(4) Install the knee blocker and reinforcement
(Refer to 23 - BODY/INSTRUMENT PANEL/KNEE
BLOCKER REINFORCEMENT - INSTALLATION).
(5) Install the lower instrument panel silencer.
(6) Connect the battery negative cable.
(7) Verify proper operation of BCM and its func-
tions.
CONTROLLER ANTILOCK
BRAKE
DESCRIPTION
The controller antilock brake (CAB) is a micropro-
cessor-based device which monitors the antilock
brake system (ABS) during normal braking and con-
trols it when the vehicle is in an ABS stop. The CAB
is mounted to the HCU as part of the integrated con-
trol unit (ICU) (Fig. 1). The CAB uses a 24-way elec-
trical connector on the vehicle wiring harness. The
power source for the CAB is through the ignition
switch in the RUN or ON position. The CAB is on
the PCI bus.
OPERATION
The primary functions of the controller antilock
brake (CAB) are to:
²Monitor the antilock brake system for proper
operation.
²Detect wheel locking or wheel slipping tenden-
cies by monitoring the speed of all four wheels of the
vehicle.
²Control fluid modulation to the wheel brakes
while the system is in an ABS mode.
²Store diagnostic information.
²Provide communication to the DRBIIItscan tool
while in diagnostic mode.
²Illuminate the amber ABS warning indicator
lamp.
²(With traction control only) Illuminate the TRAC
ON lamp in the message center on the instrument
panel when a traction control event occurs.
²(with traction control only) Illuminate the TRAC
OFF lamp when the amber ABS warning indicator
lamp illuminates.
The CAB constantly monitors the antilock brake
system for proper operation. If the CAB detects a
fault, it will turn on the amber ABS warning indica-
tor lamp and disable the antilock braking system.
The normal base braking system will remain opera-
tional.
NOTE: If the vehicle is equipped with traction con-
trol, the TRAC OFF lamp will illuminate anytime the
amber ABS warning indicator lamp illuminates.
The CAB continuously monitors the speed of each
wheel through the signals generated by the wheel
speed sensors to determine if any wheel is beginning
to lock. When a wheel locking tendency is detected,
the CAB commands the CAB command coils to actu-
ate. The coils then open and close the valves in the
HCU that modulate brake fluid pressure in some or
all of the hydraulic circuits. The CAB continues to
control pressure in individual hydraulic circuits until
a locking tendency is no longer present.
The CAB contains a self-diagnostic program that
monitors the antilock brake system for system faults.
When a fault is detected, the amber ABS warning
indicator lamp is turned on and the fault diagnostic
trouble code (DTC) is then stored in a diagnostic pro-
gram memory. A latched fault will disable certain
system functionality for the current ignition cycle. An
unlatched fault will disable certain system function-
ality until the fault condition disappears. These
DTC's will remain in the CAB memory even after the
ignition has been turned off. The DTC's can be read
and cleared from the CAB memory by a technician
using the DRBIIItscan tool. If not cleared with a
DRBIIItscan tool, the fault occurrence and DTC will
Fig. 1 Integrated Control Unit (ICU)
1 - PUMP/MOTOR
2 - HCU
3 - PUMP/MOTOR CONNECTOR
4 - CAB
RSELECTRONIC CONTROL MODULES8E-5
BODY CONTROL MODULE (Continued)

NOTE: PCM Inputs:
²Air Conditioning Pressure Transducer
²Ambient temperature Sensor
²ASD Relay
²Battery Temperature Sensor (NGC)
²Battery Voltage
²Brake Switch
²Camshaft Position Sensor
²Crankshaft Position Sensor
²Distance Sensor (from transmission control mod-
ule)
²EGR Position Feedback
²Engine Coolant Temperature Sensor
²Heated Oxygen Sensors
²Ignition sense
²Intake Air Temperature Sensor
²Knock Sensor
²Leak Detection Pump Feedback
²Manifold Absolute Pressure (MAP) Sensor
²Park/Neutral
²PCI Bus
²Power Steering Pressure Switch
²Proportional Purge Sense
²SCI Receive
²Speed Control
²Throttle Position Sensor
²Torque Management Input
²Transaxle Control Module (3.3/3.8L Only)
²Transmission Control Relay (Switched B+) (2.4L
Only)
²Transmission Pressure Switches (2.4L Only)
²Transmission Temperature Sensor (2.4L Only)
²Transmission Input Shaft Speed Sensor (2.4L
Only)
²Transmission Output Shaft Speed Sensor (2.4L
Only)
²Transaxle Gear Engagement
²Vehicle Speed
NOTE: PCM Outputs:
²Air Conditioning Clutch Relay
²Automatic Shut Down (ASD) and Fuel Pump
Relays
²Data Link Connector (PCI and SCI Transmit)
²Double Start Override
²EGR Solenoid
²Fuel Injectors
²Generator Field
²High Speed Fan Relay
²Idle Air Control Motor
²Ignition Coils
²Leak Detection Pump
²Low Speed Fan Relay
²MTV Actuator
²Proportional Purge Solenoid²SRV Valve
²Speed Control Relay
²Speed Control Vent Relay
²Speed Control Vacuum Relay
²8 Volt Output
²5 Volt Output
²Torque Reduction Request
²Transmission Control Relay (2.4L Only)
²Transmission Solenoids (2.4L Only)
²Vehicle Speed
Based on inputs it receives, the powertrain control
module (PCM) adjusts fuel injector pulse width, idle
speed, ignition timing, and canister purge operation.
The PCM regulates the cooling fans, air conditioning
and speed control systems. The PCM changes gener-
ator charge rate by adjusting the generator field.
The PCM adjusts injector pulse width (air-fuel
ratio) based on the following inputs.
²Battery Voltage
²Intake Air Temperature Sensor
²Engine Coolant Temperature
²Engine Speed (crankshaft position sensor)
²Exhaust Gas Oxygen Content (heated oxygen
sensors)
²Manifold Absolute Pressure
²Throttle Position
The PCM adjusts engine idle speed through the
idle air control motor based on the following inputs.
²Brake Switch
²Engine Coolant Temperature
²Engine Speed (crankshaft position sensor)
²Park/Neutral
²Transaxle Gear Engagement
²Throttle Position
²Vehicle Speed
The PCM adjusts ignition timing based on the fol-
lowing inputs.
²Intake Air Temperature
²Engine Coolant Temperature
²Engine Speed (crankshaft position sensor)
²Knock Sensor
²Manifold Absolute Pressure
²Park/Neutral
²Transaxle Gear Engagement
²Throttle Position
The automatic shut down (ASD) and fuel pump
relays are mounted externally, but turned on and off
by the powertrain control module through the same
circuit.
The camshaft and crankshaft signals are sent to
the powertrain control module. If the PCM does not
receive both signals within approximately one second
of engine cranking, it deactivates the ASD and fuel
pump relays. When these relays are deactivated,
power is shut off to the fuel injectors, ignition coils,
8E - 12 ELECTRONIC CONTROL MODULESRS
POWERTRAIN CONTROL MODULE (Continued)

fuel pump and the heating element in each oxygen
sensor.
The PCM contains a voltage converter that
changes battery voltage to a regulated 8.0 volts. The
8.0 volts power the camshaft position sensor, crank-
shaft position sensor and vehicle speed sensor. The
PCM also provides a 5.0 volts supply for the engine
coolant temperature sensor, intake air temperature
sensor, manifold absolute pressure sensor and throt-
tle position sensor.
The PCM engine control strategy prevents reduced
idle speeds until after the engine operates for 320 km
(200 miles). If the PCM is replaced after 320 km (200
miles) of usage, update the mileage in new PCM. Use
the DRBIIItscan tool to change the mileage in the
PCM. Refer to the appropriate Powertrain Diagnostic
Manual and the DRBIIItscan tool.
TRANSMISSION CONTROL (2.4L MODELS ONLY)
CLUTCH VOLUME INDEX (CVI)
An important function of the PCM is to monitor
Clutch Volume Index (CVI). CVIs represent the vol-
ume of fluid needed to compress a clutch pack.
The PCM monitors gear ratio changes by monitor-
ing the Input and Output Speed Sensors. The Input,
or Turbine Speed Sensor sends an electrical signal to
the PCM that represents input shaft rpm. The Out-
put Speed Sensor provides the PCM with output
shaft speed information.
By comparing the two inputs, the PCM can deter-
mine transaxle gear ratio. This is important to the
CVI calculation because the PCM determines CVIs
by monitoring how long it takes for a gear change to
occur (Fig. 10).
Gear ratios can be determined by using the DRB
Scan Tool and reading the Input/Output Speed Sen-
sor values in the ªMonitorsº display. Gear ratio can
be obtained by dividing the Input Speed Sensor value
by the Output Speed Sensor value.
For example, if the input shaft is rotating at 1000
rpm and the output shaft is rotating at 500 rpm,
then the PCM can determine that the gear ratio is
2:1. In direct drive (3rd gear), the gear ratio changesto 1:1. The gear ratio changes as clutches are applied
and released. By monitoring the length of time it
takes for the gear ratio to change following a shift
request, the PCM can determine the volume of fluid
used to apply or release a friction element.
The volume of transmission fluid needed to apply
the friction elements are continuously updated for
adaptive controls. As friction material wears, the vol-
ume of fluid need to apply the element increases.
Certain mechanical problems within the clutch
assemblies (broken return springs, out of position
snap rings, excessive clutch pack clearance, improper
assembly, etc.) can cause inadequate or out-of-range
clutch volumes. Also, defective Input/Output Speed
Sensors and wiring can cause these conditions. The
following chart identifies the appropriate clutch vol-
umes and when they are monitored/updated:
CLUTCH VOLUMES
ClutchWhen Updated
Proper Clutch
Volume
Shift Sequence Oil Temperature Throttle Angle
L/R2-1 or 3-1 coast
downshift>70É <5É 35to83
2/4 1-2 shift
> 110É5 - 54É20 to 77
OD 2-3 shift 48 to 150
UD 4-3 or 4-2 shift > 5É 24 to 70
Fig. 10 Example of CVI Calculation
1 - OUTPUT SPEED SENSOR
2 - OUTPUT SHAFT
3 - CLUTCH PACK
4 - SEPARATOR PLATE
5 - FRICTION DISCS
6 - INPUT SHAFT
7 - INPUT SPEED SENSOR
8 - PISTON AND SEAL
RSELECTRONIC CONTROL MODULES8E-13
POWERTRAIN CONTROL MODULE (Continued)

OPERATION - SENSOR RETURN - PCM INPUT
The sensor return circuit provides a low electrical
noise ground reference for all of the systems sensors.
The sensor return circuit connects to internal ground
circuits within the Powertrain Control Module
(PCM).
OPERATION - DATA BUS COMMUNICATION
RECEIVE - PCM INPUT
The PCM uses the SCI communication bus to pre-
form engine diagnostics and flash operations. The
transmission side of the PCM uses the SCI commu-
nication bus to flash new software. However, diagnos-
tics is performed via the vehicles J1850 bus for the
transmission side of the PCM.
OPERATION - IGNITION SENSE - PCM INPUT
The ignition sense input informs the Powertrain
Control Module (PCM) that the ignition switch is in
the crank or run position.
OPERATION - PCM GROUND
Ground is provided through multiple pins of the
PCM connector. Depending on the vehicle there may
be as many as two different ground pins. There are
power grounds and sensor grounds.
The power grounds are used to control the ground
side relays, solenoids, ignition coil or injectors. The
signal ground is used for any input that uses sensor
return for ground, and the ground side of any inter-
nal processing component.
The PCM case is shielded to prevent RFI and EMI.
The PCM case is grounded and must be firmly
attached to a good, clean body ground.
Internally all grounds are connected together, how-
ever there is noise suppression on the sensor ground.
For EMI and RFI protection the housing and cover
are also grounded separately from the ground pins.
OPERATION
OPERATION - 8-VOLT SUPPLY - PCM OUTPUT
- SBEC CONTROLLER
The PCM supplies 8 volts to the crankshaft posi-
tion sensor, camshaft position sensor.
OPERATION - 5 VOLT SUPPLY - PCM OUTPUT
The PCM supplies 5 volts to the following sensors:
²A/C pressure transducer
²Ambient Temperature sensor
²Battery temperature
²Camshaft Position Sensor (NGC)
²Crankshaft Position Sensor (NGC)
²Electronic Throttle Control (1.6L)²Engine coolant temperature sensor
²Inlet Air Temperature Sensor
²Knock sensor
²Linear EGR solenoid (if equipped)
²Manifold absolute pressure sensor
²Oil Pressure Switch
²Pedal Position Sensor (1.6L)
²Throttle position sensor
²Vehicle Speed Sensor
STANDARD PROCEDURE
STANDARD PROCEDURE - OBTAINING
DIAGNOSTIC TROUBLE CODES
BULB CHECK
Key on: Bulb illuminated until vehicle starts, as
long as all once per trip (readiness) monitors com-
pleted. If monitors havenotbeen completed, then:
Key on: bulb check for about 5 to 8 seconds, lamp
then flashes if once per trip (readiness) monitors
havenotbeen completed until vehicle is started,
then MIL is extinguished.
OBTAINING DTC'S USING DRB SCAN TOOL
(1) Connect the DRB scan tool to the data link
(diagnostic) connector. This connector is located in
the passenger compartment; at the lower edge of
instrument panel; near the steering column.
(2) Turn the ignition switch on and access the
ªRead Faultº screen.
(3) Record all the DTC's and ªfreeze frameº infor-
mation shown on the DRB scan tool.
(4) To erase DTC's, use the ªErase Trouble Codeº
data screen on the DRB scan tool.Do not erase any
DTC's until problems have been investigated
and repairs have been performed.
STANDARD PROCEDURE - PINION FACTOR
SETTING
NOTE: This procedure must be performed if the
PCM/TCM has been replaced with a NEW or
replacement unit. Failure to perform this procedure
will result in an inoperative or improperly calibrated
speedometer.
The vehicle speed readings for the speedometer are
taken from the output speed sensor. The PCM/TCM
must be calibrated to the different combinations of
equipment (final drive and tires) available. Pinion
Factor allows the technician to set the Powertrain/
Transmission Control Module initial setting so that
the speedometer readings will be correct. To properly
RSELECTRONIC CONTROL MODULES8E-15
POWERTRAIN CONTROL MODULE (Continued)

Refer to the appropriate Powertrain Diagnostic Man-
ual and the DRBIIItscan tool.
(1) Install PCM module to the mounting bracket.
(2) Install electrical connectors and lock.
(3) Install the splash shield.
(4) Lower vehicle.
(5) Connect the negative battery cable.
(6) Using DRBIIItscan tool, program mileage and
vehicle identification number (VIN) into PCM. Refer
to the DRBIIItscan tool and the appropriate Power-
train Diagnostic Manual.
SENTRY KEY IMMOBILIZER
MODULE
DESCRIPTION
The Sentry Key Immobilizer Module (SKIM) con-
tains a Radio Frequency (RF) transceiver and a
microprocessor. The SKIM retains in memory the ID
numbers of any Sentry Key that is programmed to it.
The maximum number of keys that may be pro-
grammed to each module is eight (8). The SKIM also
communicates over the Programmable Communica-
tion Interface (PCI) data bus with the Powertrain
Control Module (PCM), the Body Control Module
(BCM), the Mechanical Instrument Cluster (MIC),
and the DRB IIItscan tool. The SKIM transmits and
receives RF signals through a tuned antenna
enclosed within a molded plastic ring formation that
is integral to the SKIM housing. When the SKIM is
properly installed on the steering column, the
antenna ring fits snugly around the circumference of
the ignition lock cylinder housing. If this ring is not
mounted properly, communication problems may
arise in the form of transponder-related faults.
For added system security, each SKIM 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 SKIM 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
SKIM for service. The SKIM also stores in its mem-
ory the Vehicle Identification Number (VIN), which itlearns through a bus message from the assembly
plant tester. The SKIS scrambles the information
that is communicated between its components in
order to reduce the possibility of unauthorized SKIM
access and/or disabling.
OPERATION
When the ignition switch is moved to the RUN
position, the Sentry Key Immobilizer Module (SKIM)
transmits an Radio Frequency (RF) signal to the
transponder in the ignition key. The SKIM then
waits for a response RF signal from the transponder
in the key. If the response received identifies the key
as valid, the SKIM sends a9valid key9message to
the Powertrain Control Module (PCM) over the Pro-
grammable Communication Interface (PCI) data bus.
If the response received identifies the key as invalid
or no response is received from the transponder in
the ignition key, the SKIM sends an9invalid key9
message to the PCM. The PCM will enable or disable
engine operation based upon the status of the SKIM
messages. It is important to note that the default
condition in the PCM is9invalid key.9Therefore, if no
response is received by the PCM, the engine will be
immobilized after two (2) seconds of running.
The SKIM also sends indicator light status mes-
sages to the Mechanical Instrument Cluster (MIC) to
operate the light. This is the method used to turn the
light ON solid or to flash it after the indicator light
test is complete to signify a fault in the SKIS. If the
light comes ON and stays ON solid after the indica-
tor light test, this signifies that the SKIM has
detected a system malfunction and/or that the SKIS
has become inoperative. If the SKIM detects an
invalid keyORa key-related fault exists, the indica-
tor light will flash following the indicator light test.
The SKIM may also request an audible chime if the
customer key programming feature is available and
the procedure is being utilized (Refer to 8 - ELEC-
TRICAL/VEHICLE THEFT SECURITY/TRANSPON-
DER KEY - STANDARD PROCEDURE).
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove Lower Instrument Panel Cover. Refer
to Body, Instrument Panel, Lower Instrument Panel
Cover, Removal.
(3) Remove the steering column upper and lower
shrouds. Refer to Steering, Column, Column Shroud,
Removal.
(4) Disengage the steering column wire harness
from the Sentry Key Immobilizer Module (SKIM).
(5) Remove the one screws securing the SKIM to
the steering column.
8E - 18 ELECTRONIC CONTROL MODULESRS
POWERTRAIN CONTROL MODULE (Continued)