change time CHRYSLER VOYAGER 2001 Workshop Manual

TEST ACTION APPLICABILITY
2 Examine the door for proper fit and alignment, loose/ hard or torn seals, worn teeth
on the rack and gear (lower drive unit) or anything that would cause an obstruction
to proper operation.
Manually operate the other sliding door or of a known good vehicle and notice the
effort needed to open and close.
Compare the effort needed on the disabled door.
Does it take more effort to operate the door than it should?All
Ye s®Refer to Service information for the related symptom(s).
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 3
3 With the DRBIIItin Inputs/Outputs, read the PAWL, RATCHET and FULL OPEN
switch state.
While observing the FULL OPEN switch state, manually move the door from full
open to part open. The switch should toggle from CLOSED to OPEN.
Move the door to the full open position. While observing the PAWL switch state, click
the latch with a screwdriver to the first detent. The PAWL should toggle from
CLOSED to OPEN.
Move the door to the full open position. While observing the RATCHET switch state,
click the latch with a screwdriver to the second detent. The RATCHET should toggle
from CLOSED to OPEN.
Repeat the above steps several times.
Select which switch failed:All
FULL OPEN Switch
Go To 4
PAWL Switch
Go To 8
RATCHET Switch
Go To 11
All switches operated properly.
Go To 14
4 Disconnect the Sliding Door Control Module C2 connector.
Measure the resistance between ground and the Full Open Switch Sense circuit.
Open the sliding door completely then partially close it. Repeat this step while
observing the ohmmeter.
Did the resistance change from below 15 ohms to above 1000.0 ohms while moving
the door?All
Ye s®Replace the Power Sliding Door Module.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 5
5 Disconnect the Sliding Door Control Module C2 connector.
Disconnect the Full open Switch Sense wire at the lower drive unit.
Measure the resistance of the Full Open Switch Sense wire between the PSD C2
connector and the Full Open Switch connector.
Is the resistance below 5.0 ohms?All
Ye s®Go To 6
No®Repair the Full Open Switch Sense wire for an open.
Perform BODY VERIFICATION TEST - VER 1.
877
POWER DOORS - SLIDING
INCOMPLETE POWER OPEN - LATCH FAILURE ÐContinued

TEST ACTION APPLICABILITY
4 Turn the ignition off.
Disconnect the Front Wiper Module harness connector.
Turn the ignition on.
With the DRB, select Body, Body Computer then Inputs/Outputs and read the Wiper
Park Sw state.
Connect one end of a jumper wire to the Front Wiper Park Switch Sense circuit at the
Front Wiper Module harness connector.
Momentarily connect the other end of the jumper wire to ground. Repeat this several
times.
Did the Switch state change between Open and Closed when connecting and
disconnecting the jumper?All
Ye s®Replace the Front Wiper Module.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 5
5 Turn the ignition off.
Disconnect the Front Wiper Module harness connector.
Disconnect the FCM from the IPM.
Measure the resistance of the Front Wiper Park Switch Sense circuit.
Is the resistance below 10.0 ohms?All
Ye s®Replace the Front Control Module.
Perform BODY VERIFICATION TEST - VER 1.
No®Repair the Front Wiper Park Switch Sense circuit for an open.
Perform BODY VERIFICATION TEST - VER 1.
964
WINDSHIELD WIPER & WASHER
FRONT WIPER NOT PARKED ÐContinued

1.0 INTRODUCTION
The procedures contained in this manual include
all the specifications, instructions, and graphics
needed to diagnose Mark 20 Antilock Braking Sys-
tem (ABS) and Mark 20 Antilock Braking System
with Traction Control. The diagnostics in this man-
ual are based on the failure condition or symptom
being present at time of diagnosis.
Please follow the recommendations below when
choosing your diagnostic path.
1. First make sure the DRBIIItis communicating
with the CAB. If the DRBIIItdisplays a ªNo
Responseº condition, you must diagnose that
first.
2. Read DTC's (diagnostic trouble codes) with the
DRBIIIt.
3. If no DTC's are present, identify the customer
complaint.
4. Once the DTC or customer complaint is identi-
fied, locate the matching test in the Table of
Contents and begin to diagnose the symptom.
All component location views are in Section 8.0.
All connector pinouts are in Section 9.0. All sche-
matics are in Section 10.0.
An * placed before the symptom description indi-
cates a concern with no associated DTC.
When repairs are required, refer to the appropri-
ate service manual for the proper removal and
repair procedure.
Diagnostic procedures change every year. New
diagnostic systems may be added; carry over sys-
tems may be enhanced. READ THIS MANUAL
BEFORE TRYING TO DIAGNOSE A VEHICLE
CODE. It is recommended that you review the
entire manual to become familiar with all new and
changed diagnostic procedures.
After using this book, if you have any comments
or recommendations, please fill out the form at the
back of the book and mail it back to us.
1.1 SYSTEM COVERAGE
This diagnostic procedure manual covers the an-
tilock braking system (ABS) and traction control
system found on: 2001 Chrysler Town and Country,
Dodge Caravan and Grand Caravan.
1.2 SIX-STEP TROUBLESHOOTING
PROCEDURE
Diagnosis of the controller antilock brake module
is done in six basic steps:
²verification of complaint
²verification of any related symptoms
²symptom analysis
²problem isolation
²repair of isolated problem
²verification of proper operation
2.0 IDENTIFICATION OF
SYSTEM
Vehicles equipped with the Teves Mark 20 an-
tilock brake system can be identified by the pres-
ence of the controller antilock brake module located
beneath the master cylinder.
3.0 SYSTEM DESCRIPTION AND
FUNCTIONAL OPERATION
3.1 TEVES MARK 20 SYSTEM
DESCRIPTION
The controller antilock brake module is used to
monitor wheel speeds and to modulate (control)
hydraulic pressure in each brake channel. The
modulated hydraulic pressure is used to prevent
wheel lock-up during braking.
The Teves Mark 20 system uses a diagonal split
hydraulic brake system.
In the standard brake mode
the master cylinder primary circuit supplies pressure
to the right front and left rear wheel brakes, and the
secondary master cylinder circuit supplies pressure
to the left front and right rear wheel brakes.
3.2 TRACTION CONTROL SYSTEM (TCS)
DESCRIPTION
The main purpose of traction control is to reduce
wheel slip and maintain traction at the driven
wheels when road surfaces are slippery. The trac-
tion control system reduces wheel slip by braking
the wheel that is losing traction. The system is
designed to operate at speeds below 56 km/h (35
mph).
The Controller Antilock Brake (CAB) monitors
wheel speeds. If, during acceleration, the module
detects front (drive) wheel slip and the brakes are
not applied, the CAB will enter traction control
mode. Traction control works in the following order
when drive wheel slip is detected.
1. Close the (normally open) isolation valves.
2. Start pump/motor and supply volume/pressure
to front hydraulic circuits (pump runs continu-
ously during traction control).
3. Open and close build and decay valves to main-
tain minimum wheel slip and maximum trac-
tion.
1
GENERAL INFORMATION

4.0 DISCLAIMERS, SAFETY,
WARNINGS
4.1 DISCLAIMERS
All information, illustrations, and specifications
contained in this manual are based on the latest
information available at the time of publication.
The right is reserved to make changes at any time
without notice.
4.2 SAFETY
4.2.1 TECHNICIAN SAFETY INFORMATION
WARNING: ENGINES PRODUCE CARBON
MONOXIDE THAT IS ODORLESS, CAUSES
SLOWER REACTION TIME, AND CAN LEAD
TO SERIOUS INJURY. WHEN THE ENGINE IS
OPERATING, KEEP SERVICE AREAS WELL
VENTILATED OR ATTACH THE VEHICLE
EXHAUST SYSTEM TO THE SHOP EXHAUST
REMOVAL SYSTEM.
Set the parking brake and block the wheels before
testing or repairing the vehicle. It is especially
important to block the wheels on front-wheel drive
vehicles; the parking brake does not hold the drive
wheels.
When servicing a vehicle, always wear eye pro-
tection, and remove any metal jewelry such as
rings, watchbands or bracelets that might make an
inadvertent electrical contact.
When diagnosing a chassis problem, it is impor-
tant to follow approved procedures where applica-
ble. These procedures can be found in the service
manual. Following these procedures is very impor-
tant to the safety of individuals performing diag-
nostic tests.
4.2.2 VEHICLE PREPARATION FOR
TESTING
Make sure the vehicle being tested has a fully
charged battery. If is does not, false diagnostic codes
or error messages may occur.
4.2.3 SERVICING SUB-ASSEMBLIES
Some components of the chassis system are in-
tended to be serviced as an assembly only. Attempt-
ing to remove or repair certain system sub-
components may result in personal injury and/or
improper system operation. Only those components
with approved repair and installation procedures in
the service manual should be serviced.
4.2.4 DRBIIITSAFETY INFORMATION
WARNING: EXCEEDING THE LIMITS OF THE
DRB MULTIMETER IS DANGEROUS. IT CAN
EXPOSE YOU TO SERIOUS OR POSSIBLY
FATAL INJURY. CAREFULLY READ AND
UNDERSTAND THE CAUTIONS AND THE
SPECIFICATION LIMITS.
²Follow the vehicle manufacturer 's service speci-
fications at all times.
²Do not use the DRBIIItif it has been damaged.
²Do not use the test leads if the insulation is
damaged or if metal is exposed.
²To avoid electrical shock, do not touch the test
leads, tips, or the circuit being tested.
²Choose the proper range and functions for the
measurement. Do not try voltage or current mea-
surements that may exceed the rated capacity.
²Do not exceed the limits shown in the table below:
FUNCTION INPUT LIMIT
Volts 0 - 500 peak volts AC
0 - 500 volts DC
Ohms (resistance)* 0 -1.12 megohms
Frequency Measured
Frequency Generated0-10kHz
Temperature -58 - 1100ÉF
-50 - 600ÉC
* Ohms cannot be measured if voltage is present.
Ohms can be measured only in a non-powered
circuit.
²Voltage between any terminal and ground must
not exceed 500v DC or 500v peak AC.
²Use caution when measuring voltage above 25v
DC or 25v AC.
²Use the low current shunt to measure circuits up
to 10A. Use the high current clamp to measure
circuits exceeding 10A.
²When testing for the presence of voltage or cur-
rent, make sure the meter is functioning cor-
rectly. Take a reading of a known voltage or
current before accepting a zero reading.
²When measuring current, connect the meter in
series with the load.
²Disconnect the live test lead before disconnecting
the common test lead.
²When using the meter function, keep the
DRBIIItaway from spark plug or coil wires to
avoid measuring error from outside interference.
5
GENERAL INFORMATION

Symptom:
LEFT FRONT WHEEL SPEED SIGNAL FAILURE
When Monitored and Set Condition:
LEFT FRONT WHEEL SPEED SIGNAL FAILURE
When Monitored: Wheel speed comparison is checked at drive off or every 7 milliseconds
(ms). Sensor signal continuity is checked every 7 milliseconds. Wheel speed phase length
supervision is checked every 7 milliseconds.
Set Condition: If, during an ABS stop, the CAB commands any valve solenoid on for an
extended length of time, and does not see a corresponding wheel speed change, the
Diagnostic Trouble Code (DTC) is set. The DTC can also set if the signal is missing or
erratic.
POSSIBLE CAUSES
SENSOR OR TONE WHEEL CONCERN
DTC INTERMITTENT
LEFT FRONT WHEEL SPEED SENSOR INOPERATIVE
INTERMITTENT SIGNAL DTC
TEST ACTION APPLICABILITY
1 With the DRBIIIt, erase DTCs.
Turn the ignition off.
Start the engine.
Slowly accelerate as straight as possible from a stop to 24 km/h (15 mph).
Using the DRBIIIt, monitor the Left Front Wheel Speed Sensor while an assistant
drives the vehicle.
With the DRBIIIt, monitor all wheel speed sensors.
Is Left Front WSS Signal 0 km/h (0 mph) or differing from others by more than 5
km/h (3 mph)?All
Ye s®Go To 2
No®Go To 3
2 Inspect the Left Front Wheel Speed Sensor, Connector and Tone Wheel.
NOTE: Inspect components for damage and correct installation.
Are there any visible Sensor, Connector or Tone Wheel concerns?All
Ye s®Correct the sensor, connector or tone wheel concern as necessary.
The vehicle must be driven at 25 km/h (15 mph) to extinguish the
ABS indicator.
Perform ABS VERIFICATION TEST - VER 1.
No®Replace the Left Front Wheel Speed Sensor in accordance with
the Service Information. The vehicle must be driven at 25 km/h
(15 mph) to extinguish the ABS indicator.
Perform ABS VERIFICATION TEST - VER 1.
17
BRAKES (CAB)

Symptom:
LEFT REAR WHEEL SPEED SIGNAL FAILURE
When Monitored and Set Condition:
LEFT REAR WHEEL SPEED SIGNAL FAILURE
When Monitored: Wheel speed comparison is checked at drive off or every 7 milliseconds
(ms). Wheel speed circuit continuity is checked every 7 milliseconds. Wheel speed phase
length supervision is checked every 7 milliseconds.
Set Condition: If, during an ABS stop, the CAB commands any valve solenoid on for an
extended length of time, and does not see a corresponding wheel speed change, the
Diagnostic Trouble Code (DTC) is set. The DTC can also set if the signal is missing or
erratic.
POSSIBLE CAUSES
SENSOR OR TONE WHEEL CONCERN
DTC INTERMITTENT
LEFT REAR WHEEL SPEED SENSOR INOPERATIVE
INTERMITTENT SIGNAL DTC
TEST ACTION APPLICABILITY
1 With the DRBIIIt, erase DTCs.
Turn the ignition off.
Start the engine.
Slowly accelerate as straight as possible from a stop to 24 km/h (15 mph).
Using the DRBIIIt, monitor the Left Rear Wheel Speed Sensor while an assistant
drives the vehicle.
With the DRBIIIt, monitor all wheel speed sensors.
Is Left Rear WSS Signal 0 km/h (0 mph) or differing from others by more than 5 km/h
(3 mph)?All
Ye s®Go To 2
No®Go To 3
2 Inspect the Left Rear Wheel Speed Sensor, Connector and Tone Wheel.
NOTE: Inspect components for damage and correct installation.
Are there any visible Sensor, Connector or Tone Wheel concerns?All
Ye s®Correct the sensor, connector or tone wheel concern as necessary.
The vehicle must be driven at 25 km/h (15 mph) to extinguish the
ABS indicator.
Perform ABS VERIFICATION TEST - VER 1.
No®Replace the Left Rear Wheel Speed Sensor in accordance with the
Service Information. The vehicle must be driven at 25 km/h (15
mph) to extinguish the ABS indicator.
Perform ABS VERIFICATION TEST - VER 1.
19
BRAKES (CAB)

Symptom:
RIGHT FRONT WHEEL SPEED SIGNAL FAILURE
When Monitored and Set Condition:
RIGHT FRONT WHEEL SPEED SIGNAL FAILURE
When Monitored: Wheel speed comparison is checked at drive off or every 7 milliseconds
(ms). Wheel speed continuity is checked every 7 milliseconds. Wheel speed phase length
supervision is checked every 7 milliseconds.
Set Condition: If, during an ABS stop, the CAB commands any valve solenoid on for an
extended length of time, and does not see a corresponding wheel speed change, the
Diagnostic Trouble Code (DTC) is set. The DTC can also set if the signal is missing or
erratic.
POSSIBLE CAUSES
SENSOR OR TONE WHEEL CONCERN
DTC INTERMITTENT
RIGHT FRONT WHEEL SPEED SENSOR INOPERATIVE
CAB - WON'T RESPOND TO RIGHT FRONT WHEEL SPEED SENSOR SIGNAL
INTERMITTENT SIGNAL DTC
TEST ACTION APPLICABILITY
1 With the DRBIIIt, erase DTCs.
Turn the ignition off.
Start the engine.
Slowly accelerate as straight as possible from a stop to 24 km/h (15 mph).
Using the DRBIIIt, monitor the Right Front Wheel Speed Sensor while an assistant
drives the vehicle.
With the DRBIIIt, monitor all wheel speed sensors.
Is Right Front WSS Signal 0 km/h (0 mph) or differing from others by more than 5
km/h (3 mph)?All
Ye s®Go To 2
No®Go To 3
2 Inspect the Right Front Wheel Speed Sensor, Connector and Tone Wheel.
NOTE: Inspect components for damage and correct installation.
Are there any visible Sensor, Connector or Tone Wheel concerns?All
Ye s®Correct the sensor, connector or tone wheel concern as necessary.
The vehicle must be driven at 25 km/h (15 mph) to extinguish the
ABS indicator.
Perform ABS VERIFICATION TEST - VER 1.
No®Replace the Right Front Wheel Speed Sensor in accordance with
the Service Information. The vehicle must be driven at 25 km/h
(15 mph) to extinguish the ABS indicator.
Perform ABS VERIFICATION TEST - VER 1.
24
BRAKES (CAB)

Symptom:
RIGHT REAR WHEEL SPEED SIGNAL FAILURE
When Monitored and Set Condition:
RIGHT REAR WHEEL SPEED SIGNAL FAILURE
When Monitored: Wheel speed comparison is checked at drive off or every 7 milliseconds
(ms). Wheel speed circuit continuity is checked every 7 milliseconds. Wheel speed phase
length supervision is checked every 7 milliseconds.
Set Condition: If, during an ABS stop, the CAB commands any valve solenoid on for an
extended length of time, and does not see a corresponding wheel speed change, the
Diagnostic Trouble Code (DTC) is set. The DTC can also set if the signal is missing or
erratic.
POSSIBLE CAUSES
SENSOR OR TONE WHEEL CONCERN
DTC INTERMITTENT
RIGHT REAR WHEEL SPEED SENSOR INOPERATIVE
INTERMITTENT SIGNAL DTC
TEST ACTION APPLICABILITY
1 With the DRBIIIt, erase DTCs.
Turn the ignition off.
Start the engine.
Slowly accelerate as straight as possible from a stop to 24 km/h (15 mph).
Using the DRBIIIt, monitor the Right Rear Wheel Speed Sensor while an assistant
drives the vehicle.
With the DRBIIIt, monitor all wheel speed sensors.
Is Right Rear WSS Signal 0 km/h (0 mph) or differing from others by more than 5
km/h (3 mph)?All
Ye s®Go To 2
No®Go To 3
2 Inspect the Right Rear Wheel Speed Sensor, Connector and Tone Wheel.
NOTE: Inspect components for damage and correct installation.
Are there any visible Sensor, Connector or Tone Wheel concerns?All
Ye s®Correct the sensor, connector or tone wheel concern as necessary.
The vehicle must be driven at 25 km/h (15 mph) to extinguish the
ABS indicator.
Perform ABS VERIFICATION TEST - VER 1.
No®Replace the Left Rear Wheel Speed Sensor in accordance with the
Service Information. The vehicle must be driven at 25 km/h (15
mph) to extinguish the ABS indicator.
Perform ABS VERIFICATION TEST - VER 1.
26
BRAKES (CAB)

1.0 INTRODUCTION
The procedures contained in this manual include
all the specifications, instructions and graphics
needed to diagnose engine control module (ECM)
and sentry key immobilizer system (SKIS) prob-
lems; they are no start, diagnostic trouble code
(DTC), and no trouble code problems for the ECM.
The diagnostics in this manual are based on the
trouble condition or symptom being present at the
time of diagnosis.
When repairs are required, refer to the appropri-
ate service information for the proper removal and
repair procedure.
Diagnostic procedures change every year. New
diagnostic systems may be added; carryover sys-
tems may be enhanced. IT IS RECOMMENDED
THAT YOU REVIEW THE ENTIRE MANUAL TO
BECOME FAMILIAR WITH ALL NEW AND
CHANGED DIAGNOSTIC PROCEDURES.
This manual is designed to begin all diagnosis at
the DTC TEST, which is located at the beginning of
Section 7.0. This will cover all the necessary re-
quirements to begin a logical diagnostic path for
each problem. If there is a diagnostic trouble code
(DTC) detected, it will direct you to the trouble code
test. If there are no DTCs present, it will direct you
by symptom to a no trouble code test.
This book reflects many suggested changes from
readers of past issues. After using this book, if you
have any comments or recommendations, please fill
out the form at the back of the book and mail it back
to us.
1.1 SYSTEM COVERAGE
This diagnostic procedures manual covers all
2001 RG body vehicles equipped with the 2.5L VM
diesel engine.
1.2 SIX-STEP TROUBLESHOOTING
PROCEDURE
Diagnosis of the engine control module (ECM)
and sentry key immobilizer system (SKIS) is done
in six basic steps:
²verification of complaint
²verification of any related symptom
²symptom analysis
²problem isolation
²repair of isolated problem
²verification of proper operation
NOTE: All tests in this manual should be per-
formed with the engine at operating temperature,
unless specified within a particular test.
2.0 IDENTIFICATION OF
SYSTEM
The ECM is located in the left side of the engine
compartment between the left front headlamp and
the intelligent power module. The sentry key immo-
bilizer module (SKIM) is located below the steering
column behind the steering wheel.
3.0 SYSTEM DESCRIPTION AND
FUNCTIONAL OPERATION
3.1 GENERAL DESCRIPTION
The 2.5L VM diesel engine system is equipped
with the latest in technical advances. The on-board
diagnostics incorporated in the engine control mod-
ule and SKIM are intended to assist the field
technician in repairing vehicle problems by the
quickest means.
The engine system incorporates a common rail
fuel delivery design. This design utilizes electroni-
cally controlled solenoid valve type fuel injectors.
Each injector is controlled individually by the ECM.
Injector timing and fuel quantity are controlled by
the ECM based on inputs from the various sensors.
The precision control of the injectors by the ECM
helps to reduce the engine noise, odor and smoke.
3.2 FUNCTIONAL OPERATION
3.2.1 ECM ON-BOARD DIAGNOSTICS
The ECM has been programmed to monitor many
different circuits of the diesel fuel injection system.
This monitoring is called on-board diagnostics.
Certain criteria must be met for a trouble code to
be entered into the ECM memory. The criteria may
be a range of: engine rpm, engine temperature, time
or other input signals to the ECM. If all of the
criteria for monitoring a system or circuit are met,
and a problem is sensed, then a DTC will be stored
in the ECM memory.
It is possible that a DTC for a monitored circuit
may not be entered into the ECM memory, even
though a malfunction has occurred. This may hap-
pen when the monitoring criteria has not been met.
The ECM compares input signal voltages from
each input device with specifications (the estab-
lished high and low limits of the input range) that
are programmed into it for that device. If the input
voltage is not within the specifications and other
trouble code criteria are met, a DTC will be stored
in the ECM memory.
1
GENERAL INFORMATION

3.2.2 ECM OPERATING MODES
As input signals to the ECM change, the ECM
adjusts its response to the output devices. For
example, the ECM must calculate a different fuel
quantity and fuel timing for engine idle condition
than it would for a wide open throttle condition.
There are several different modes of operation that
determine how the ECM responds to the various
input signals.
Ignition Switch On (Engine Off)
When the ignition switch is turned on, the ECM
activates the glow plug relay for a time period that
is determined by engine coolant temperature, atmo-
spheric temperature and battery voltage. The ECM
also activates the lift pump to prime the fuel sys-
tem.
Engine Start-up Mode
The ECM uses the engine temperature sensor
and the crankshaft position sensor (engine speed)
inputs to determine fuel injection quantity.
Normal Driving Modes
Engine idle, warm-up, acceleration, deceleration
and wide open throttle modes are controlled based
on all of the sensor inputs to the ECM. The ECM
uses these sensor inputs to adjust fuel quantity and
fuel injector timing.
Overheat Protection Mode
If engine temperature is above 106É C (223É F)
and vehicle speed is above 40 km/h (25 MPH) the
ECM will activate the high speed fan and will limit
fuel quantity for engine protection.
Limp-In Mode
If there is a fault detected with the accelerator
pedal position sensor, the ECM will set the engine
speed at 1100 RPM.
Overspeed Detection Mode
If the ECM detects engine RPM that exceeds
5000 RPM, the ECM will set a DTC in memory and
limit engine RPM to no more that 2500 RPM until
the DTC(s) is cleared.
After-Run Mode
The ECM transfers RAM information to ROM
and performs an Input/Output state check.
3.2.3 MONITORED CIRCUITS
The ECM is able to monitor and identify most
driveability related trouble conditions. Some cir-
cuits are directly monitored through ECM feedback
circuitry. In addition, the ECM monitors the voltage
state of some circuits and compares those stateswith expected values. Other systems are monitored
indirectly when the ECM conducts a rationality test
to identify problems.
Although most subsystems of the engine control
module are either directly or indirectly monitored,
there may be occasions when diagnostic trouble
codes are not immediately identified. For a trouble
code to set, a specific set of conditions must occur
and unless these conditions occur, a DTC will not
set.
3.2.4 SKIS OVERIVEW
The sentry key immobilizer system (SKIS) is
designed to prevent unauthorized vehicle opera-
tion. The system consists of a sentry key immobi-
lizer module (SKIM), ignition key(s) equipped with
a transponder chip and the ECM. When the ignition
switch is turned on, the SKIM interrogates the
ignition key. If the ignition key is Valid or Invalid,
the SKIM sends a PCI Bus message to the ECM
indicating ignition key status. Upon receiving this
message the ECM will terminate engine operation
or allow the engine to continue to operate.
3.2.5 SKIS ON-BOARD DIAGNOSTICS
The sentry key immobilizer module (SKIM) has
been programmed to transmit and monitor many
different coded messages as well as PCI Bus mes-
sages. This monitoring is called On-Board Diagnos-
tics. Certain criteria must be met for a DTC to be
entered into SKIM memory. The criteria may be a
range of; input voltage, PCI Bus message or coded
messages to the SKIM. If all of the criteria for
monitoring a circuit or function are met and a fault
is detected, a DTC will be stored in the SKIM
memory.
3.2.6 SKIS OPERATION
When ignition power is supplied to the SKIM, the
SKIM performs an internal self-test. After the self-
test is complete, the SKIM energizes the antenna
(this activates the transponder chip) and sends a
challenge to the transponder chip. The transponder
chip responds to the challenge by generating an
encrypted response message using the following:
Secret Key - This is an electronically stored value
(identification number) that is unique to each SKIS.
The secret key is stored in the SKIM, ECM and all
ignition key transponders.
Challenge - This is a random number that is gen-
erated by the SKIM at each ignition key cycle.
The secret key and challenge are the two vari-
ables used in the algorithm that produces the
encrypted response message. The transponder uses
the crypto algorithm to receive, decode and respond
to the message sent by SKIM. After responding to
the coded message, the transponder sends a tran-
2
GENERAL INFORMATION