2006 MERCEDES-BENZ SPRINTER sensor

secured to the floor under the Driver seat and
receives power from the Fuse Block No. 1. When-
ever the ignition key is turned to the run or start
position, the ACM performs a system test. The ACM
cannot be repaired or adjusted.
The microprocessor in the ACM monitors the
internal and external airbag system electrical cir-
cuits to determine the system readiness. When a
monitored system is determine to be out of range,
the ACM will set both active and stored diagnostic
trouble codes (DTC). The ACM also contains an
energy-storage capacitor. This capacitor stores
enough electrical energy to deploy the front airbag
components for two seconds following a battery
disconnect or failure during an impact.
The Accelerometer in the ACM is used to sense
the rate of vehicle deceleration, provide verification
of the direction and severity of an impact. When the
preprogrammed conditions are met, the ACM sends
an electrical signal to deploy the appropriate front
airbag system components and a deployment noti-
fication.
To provide an accident response notification, the
ACM is hardwired to the Central Timer module
(CTM) and Engine Control Module (ECM). When a
deployment occurs the ACM provides a 50ms 10.0
volt pulse to the CTM and ECM. When the Accident
Report notification signal is received the CTM un-
locks the door locks and the ECM stalls the engine.
The Accident signal will set a DTC in the CTM and
the door locks will not work until the DTC has been
erased. The ECM will set a DTC if the Accident
Report circuit is shorted to battery voltage. The
ACM saves the deployment record and after three
deployments the ACM must be replaced. The
DRBIIItcan be used to test the Accident Report
Notification feature: select the SYSTEM TEST from
the ACM main menu. Then select the Analog Crash
Output System Test.
The ACM is hardwired to the Instrument Cluster
(MIC) to control Warning Indicator (SRS indicator).
When DTCs becomes activate, the ACM illuminates
the Warning Indicator by pulling the indicator
circuit low. The SRS indicator is the only point at
which the customer can observe symptoms of a
system malfunction.
As part of the system test the ACM illuminates
the Warning Indicator on for 4.0 second bulb test.
After the lamp check, if the indicator turns off, it
means that the ACM has checked the system and
found it to be free of discernible malfunctions.
NON-CRITICAL DTCs
If the lamp comes on and stays on for a period
longer than 4.0 seconds (about 10.0 seconds) is
usually a stored DTC (intermittent problem) in the
system.
CRITICAL DTCs
DTCs that could lead to a condition where the
safety devises may not deploy or incorrectly deploy.
In the event of such a DTC, the safety of the vehicle
occupants can no longer be guaranteed. If the lamp
remains on, there could be an active DTC in the
system. Some DTCs, Internal Module and squib
DTCs, will keep the indicator illuminated even if
the codes are no longer active.
ACM NOT CONFIGURED FOR PASSENGER
AIRBAG AND TENSIONER
If after replacing the ACM the Airbag Warning
Indicator flashes continuously the ACM must be
configured for the Passenger Airbag and Tensioner.
Select Miscellaneous from the ACM main menu and
configure the Passenger Airbag Tensioner squibs.
WARNING:THE AIRBAG SYSTEM IS A
SENSITIVE, COMPLEX ELECTROMECHANICAL
UNIT. BEFORE ATTEMPTING TO DIAGNOSE OR
SERVICE ANY AIRBAG SYSTEM OR RELATED
STEERING WHEEL, STEERING COLUMN, OR
INSTRUMENT PANEL COMPONENTS YOU MUST
FIRST DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE. WAIT
TWO MINUTES FOR THE SYSTEM CAPACITOR
TO DISCHARGE BEFORE FURTHER SYSTEM
SERVICE. THIS IS THE ONLY SURE WAY TO
DISABLE THE AIRBAG SYSTEM. FAILURE TO
DO THIS COULD RESULT IN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, NEVER STRIKE OR KICK THE
AIRBAG CONTROL MODULE, AS IT CAN
DAMAGE THE IMPACT SENSOR OR AFFECT
ITS CALIBRATION.
WARNING: IF AN AIRBAG CONTROL
MODULE IS ACCIDENTALLY DROPPED
DURING SERVICE, THE MODULE MUST BE
SCRAPPED AND REPLACED WITH A NEW
UNIT. FAILURE TO TAKE THE PROPER
PRECAUTIONS COULD RESULT IN
ACCIDENTAL AIRBAG DEPLOYMENT AND
PERSONAL INJURY OR DEATH.
3.1.1 DRIVER AIRBAG
The airbag protective trim cover is the most
visible part of the driver side airbag system. The
airbag is mounted directly to the steering wheel.
Located under the trim cover are the airbag cushion
and the airbag cushion supporting components.
2
GENERAL INFORMATION

loads are connected to cables and mounted in a
storage case. The cables can be directly connected to
some airbag system connectors. Jumpers are used
to convert the load tool cable connectors to the other
airbag system connectors. The adapters are con-
nected to the module harness connector to open
shorting clips and protect the connector terminal
during testing. When using the load tool follow all of
the safety procedures in the service information for
disconnecting airbag system components. Inspect
the wiring, connector and terminals for damage or
misalignment. Substitute the airbag load tool in
place of a Driver or Passenger Airbag, seat belt
tensioner, clockspring (use a jumper if needed).
Then follow all of the safety procedures in the
service information for connecting airbag system
components. Read the module active DTCs. If the
module reports NO ACTIVE DTCs the defective
components has been removed from the system and
should be replaced. If the DTC is still active, con-
tinue this process until all components in the circuit
have been tested. Then disconnect the module con-
nector and connect the matching adapter to the
module connector. With all airbags disconnected
and the adapter installed the squib wiring can be
tested for open and shorted conditions.
3.1.6 DIAGNOSTIC TROUBLE CODES
Airbag diagnostic trouble codes consist of active
and stored codes. If more than one code exists,
diagnostic priority should be given to the active
codes. Each diagnostic trouble code is diagnosed by
following a specific testing procedure. The diagnos-
tic test procedures contain step-by-step instructions
for determining the cause of the trouble codes. It is
not necessary to perform all of the tests in this book
to diagnose an individual code. Always begin by
reading the diagnostic trouble codes with the
DRBIIIt. This will direct you to the specific test(s)
that must be performed. In certain test procedures
within this manual, diagnostic trouble codes are
used as a diagnostic tool.
3.1.6.1 ACTIVE CODES
If the lamp remains on, there could be an active
DTC in the system. The code becomes active as soon
as the malfunction is detected or key-on, whichever
occurs first. An active trouble code indicates an
on-going malfunction. This means that the defect is
currently there every time the airbag control mod-
ule checks that circuit or component. Some DTCs,
Internal Module and squib DTCs, will keep the
indicator illuminated even if they are no longer
active. If the lamp is on and no active codes are
present, cycling the ignition switch off and then on
will refresh the lamp state. It is impossible to erase
an active code.
3.1.6.2 STORED CODES
Airbag codes are automatically stored in the
ACM's memory as soon as the malfunction is de-
tected. A stored code indicates there was an active
code present at some time. Stored diagnostic trou-
ble code will remain stored until erased by the DRB.
If a malfunction is not active while performing a
diagnostic test procedure, the active code diagnostic
test will not locate the source of the problem. In this
case, the stored code can indicate an area to inspect.
Maintain a safe distance from all airbags while
performing the following inspection. If no obvious
problems are found, erase stored codes, and with
the ignition on wiggle the wire harness and connec-
tors, rotate the steering wheel from stop to stop.
Recheck for codes periodically as you work through
the system. This procedure may uncover a malfunc-
tion that is difficult to locate.
3.2 COMMUNICATION
3.2.1 COMMUNICATION K-LINES
The K-Lines are a group of circuits that connect
each control module to the Data Link Connector
(DLC). Each control module is connected to the DLC
with a single K-Line. The DRBIIItuses the K-Line
to communicate with each control module. With the
use of the K-Lines the DRBIIItis able to read each
control modules DTCs, sensor displays, I/Os etc. If
DRBIIItcommunications with a particular control
module is lost, one of the possible causes could be a
fault in the module's K-Line.
NOTE: It is important to note the DRBIIIT
uses the K-Lines for diagnostic and
monitoring functions and is no way
connected to the CAN data bus network.
The following modules that use the K-line on this
vehicle are:
²Airbag Control Module (ACM)
²Automatic Temperature Control (ATC)
²Cabin Heater Module (CHM)
²Central Timer Module (CTM)
²Controller Antilock Brake (CAB)
²Engine Control Module (ECM)
²Heater Booster Module (HBM)
²Instrument Cluster (IC)
²Shifter Assembly (SA)
²Security System Module (SSM)
²Sentry Key Remote Entry Module (SKREEM)
²Transmission Control Module (TCM)
4
GENERAL INFORMATION

3.2.2 CAN BUS
The CAN bus (controller area network) is a data
bus system specifically design for inter module
communication on this vehicle. The CAN bus con-
sists of a special twisted two-core cable. Control
modules are connected to this9twisted pair9. The
CAN bus incorporates two terminating resistors.
One terminator is built into the Engine Control
Module (ECM) and the other is built into the Sentry
Key Remote Entry Module (SKREEM). Each resis-
tor has a value of 120 ohms. The resistor condition
can be confirmed by disconnecting the control mod-
ule and measuring the resistance value at the
appropriate control module pins. This measure-
ment should read 120 ohms. The two CAN circuits,
CAN C Bus (+) and CAN C Bus (-), are bridged by
these two terminating resistors when all control
modules are connected to the bus. These two resis-
tors are connected to the CAN bus network in
parallel. The measurement between the two
twisted CAN circuits, with both the ECM and
SKREEM connected, should measure a value of 60
ohms.
The CAN bus is bi-directional. This means that
each connected control module can send and receive
information. Transmission of data takes place re-
dundantly via both circuits. The data bus levels are
mirrored, meaning that if the binary level on one
circuit is 0, the other circuit transmits binary level
1 and vice versa. The two line concept is used for
two reasons: for fault identification and as a safety
concept.
If a voltage peak occurs on just one circuit, the
receivers can identify this as a fault and ignore the
voltage peak. If a short circuit or interruption
occurs on one of the two CAN circuits, a software-
hardware linked safety concept allows switching to
a single-line operation. The defective CAN circuit is
shut down. A specific data protocol controls how and
when the participants can send and receive.
NOTE: It is important to note the CAN Bus
circuits are used for inter-module
communication only, and is no way
connected to the K-Lines.
The following modules that use the CAN Bus on
this vehicle are:
²Automatic Temperature Control (ATC)
²Controller Antilock Brake (CAB)
²Engine Control Module (ECM)
²Instrument Cluster (IC)
²Sentry Key Remote Entry Module (SKREEM)
²Shifter Assembly (SA)
²Transmission Control Module (TCM)
3.3 HEATING & A/C SYSTEM
3.3.1 AUTOMATIC TEMPERATURE
CONTROL (ATC)
3.3.1.1 SYSTEM CONTROLS
The ATC Module:
²is fully addressable with the DRBIIIt.
IThe DRBIIItcommunicates with the ATC
Module through the Diagnostic Link Connector
(DLC) via a K-Line.
²communicates with other modules over the Con-
troller Area Network (CAN) C Bus.
²controls A/C clutch operation.
²controls EBL operation.
²controls water cycle valve operation.
IThe water cycle valve is a normally open valve,
meaning that it allows full engine coolant flow
through the heater core when no power is
delivered to the valve. The ATC controls the
valve with a pulse width signal. The lower the
percentage of the pulse width signal the more
the valve is open.
²controls Residual Heat Utilization (REST) func-
tion.
²controls blower motor operation, providing four
blower speeds (Low, M1, M2, & High).
²controls recirculation air solenoid valve.
²controls the mode door via cables.
²controls the main power supply to the Heater
Booster (if equipped).
²uses air inlet temperature sensor, air outlet tem-
perature sensor, and evaporator temperature
sensor input, as well as data from other modules
to maintain occupant comfort levels.
3.3.1.2 SYSTEM DIAGNOSTICS
Fault detection is through active and stored Diag-
nostic Trouble Codes (DTCs)
²DTCs are displayed by the DRBIIIt.
²Active DTCs are those which currently exist in
the system. The condition causing the fault must
be repaired in order to clear this type of DTC.
²Stored DTCs are those which occurred in the
system since the ATC Module received the last
9clear diagnostic info9message.
Testing Preparation & Diagnostics
Set the necessary system functions accordingly so
that all of the following prerequisites are met prior
to performing diagnostic tests on the ATC system:
5
GENERAL INFORMATION

1. Connect the DRBIIItto the DLC.
2. Place the shift lever in park.
3. Start the engine.
4. Set the blower to high speed.
5. Set the temperature selector to full cold.
6. Press air conditioning switch on.
7. With the DRBIIItin Sensors, verify that the:
A. ambient temperature is above 59F (15C).
B. refrigerant pressure is between 29 and 348
PSI (2 and 24 bar).
C. evaporator temperature is above 36.5F
(2.5C).
D. coolant temperature is above 158F (70C).
When all of the prerequisites have been met, use
the DRBIIItto record and erase all stored ATC
DTCs, and then select System Tests, and run the
ATC Function Test. When complete, check to see if
any active DTCs are present. If so, refer to the
symptom list in the Heating & A/C category for the
diagnostic procedure(s). If there are no DTCs
present, yet the performance seems less than ideal,
use the DRBIIItto look at all sensor values and the
status of the various inputs and outputs to see if
there is a deficiency detected that has not fully shut
down the system. For additional information, refer
to Sensor Values and Input/Output Status under
Diagnostic Tips in this section and to Section 11.0
for evaporator temperature sensor and air outlet
temperature sensor resistance to temperature spec-
ifications charts. Also, confirm that the water cycle
valve is functioning. Remember that the valve is
normally open. The pulse width signal will offer
insight into the valve's operation. The lower the
percentage number, the more open the valve be-
comes. Confirm that the valve is responding to the
signal from the ATC. If functioning correctly, verify
mode and blend door operation. If okay, the diagno-
sis then becomes purely refrigerant system related.
Attach the appropriate gauges and diagnose the
refrigeration system. Refer to the Service Informa-
tion for refrigerant system diagnostic procedures.
DIAGNOSTIC TIPS
SENSOR VALUES
Ambient Air Temperature
The Instrument Cluster transmits Ambient Air
Temperature Sensor data. In the event of a CAN
Bus communication failure, the last stored value is
displayed as a substitute value.
Interior Temperature
The normal range for the Interior Temperature
Sensor is from 32ÉF to 104ÉF. An implausible tem-
perature value indicates that the Interior Temper-
ature Sensor is bad. The repair in this case would be
to replace the ATC Module since the sensor is
integral to the module.Evaporator Temperature
The normal range for the Evaporator Temperature
Sensor is from 14ÉF to 104ÉF. A substitute value of
14ÉF with no updates indicates an Evaporator Tem-
perature Sensor circuit failure.
Air Outlet Temperature
The normal range for the Air Outlet Temperature
Sensor is from 32ÉF to 203ÉF. A substitute value of
111.1ÉF indicates an Air Outlet Temperature Sensor
circuit failure.
Coolant Temperature
The Engine Control Module transmits Coolant
Temperature Sensor date. In the event of a CAN
Bus communication failure, 257ÉF is displayed as a
substitute value.
Interior Temperature Controller
The normal range for the Blend control is from 62ÉF
to 144ÉF. This value represents the temperature set
by the operator. An implausible temperature value
or a temperature value that fails to change when
rotating the Blend control indicates that the Blend
control is bad. The repair in this case would be to
replace the ATC Module since the Blend control
integral to the module.
Refrigerant Pressure
The normal range for the Refrigerant Pressure
Sensor is from 29 PSI to 406 PSI. A substitute value
of 413 PSI indicates a Refrigerant Pressure Sensor
circuit failure. In addition, the normal range for
Pressure Sensor voltage is 0 volts to 5 volts. A value
of 0.9 volts indicates an open voltage supply circuit,
while a value of -999 indicates an open in all three
sensor circuits.
Water Cycle Valve
The normal range of the Water Cycle Valve is from
0% to 100%. The value indicates the extent to which
the valve is closed. A value of 100% indicates that
the valve is fully closed.
Intense Inst Light
The Instrument Cluster transmits this data. The
normal range for lighting intensity is from 0% to
100%. The value indicates the extent to which the
illumination has dimmed. A value of 0% indicates
bright while a value >0% indicates dimming. In the
event of a CAN Bus communication failure, 0% is
displayed as a substitute value.
INPUT/OUTPUT STATUS
Compressor Clutch
The ATC Module transmits this data. A status of
9ON9indicates that the compressor is operational. A
status of9OFF9indicates the compressor is not
operational.
6
GENERAL INFORMATION

Compres SO Accel (Compressor Shut Off - Due
To Acceleration)
The Engine Control Module transmits this data. A
status of9YES9indicates that the compressor shut
off because of an acceleration request. A status of
9NO9indicates that there is no acceleration request.
If shut off due to an acceleration request, the
compress will switch on again after 20 seconds. In
addition, the original acceleration request can no
longer exist for the ECM to acknowledge a subse-
quent request. In the event of a CAN Bus commu-
nication failure,9NO9is displayed as a substitute
value.
Compres SO W/E-Off (Compressor Shut Off -
Due to Emergency Off)
The Engine Control Module transmits this data. A
status of9YES9indicates that the compressor shut
off because of an emergency off request. A status of
9NO9indicates that there is no emergency off re-
quest. In the event of a CAN Bus communication
failure, the last stored value is displayed as a
substitute value.
Auxiliary Fan
The ATC Module transmits this data. A status of
9ON9indicates that the auxiliary fan is operational.
A status of9OFF9indicates that the auxiliary fan is
not operational. The Auxiliary Fan normally oper-
ates when refrigerant head pressure exceeds 290
PSI and coolant temperature exceeds 221ÉF. In the
event of a CAN Bus communication failure, 257ÉF is
displayed for coolant temperature (in Sensors) and
the Auxiliary Fan will run continuously.
Light PB CTRL Module
This input displays a status of9Bright9for positive
dimmer switch operation and9Dimmed9for nega-
tive dimmer switch operation. In the event of a CAN
Bus communication failure,9Bright9is displayed.
3.3.2 CABIN HEATER MODULE (CHM) &
HEATER BOOSTER MODULE (HBM)
3.3.2.1 SYSTEM DESCRIPTION
WARNING: NEVER OPERATE THE HEATER
IN AN ENCLOSED AREA THAT DOES NOT
HAVE EXHAUST VENTILATION FACILITIES.
ALWAYS VENT THE HEATER'S EXHAUST
WHEN OPERATING THE HEATER. REFER TO
(VENTING THE HEATER'S EXHAUST(
BELOW FOR PROPER EXHAUST VENTING
INSTRUCTIONS. FAILURE TO FOLLOW
THESE INSTRUCTIONS CAN RESULT IN
PERSONAL INJURY OR DEATH.
WARNING: ALLOW THE HEATER ASSEMBLY TO
COOL BEFORE PERFORMING A COMPONENT
INSPECTION/REPAIR/REPLACEMENT. FAILURE
TO FOLLOW THESE INSTRUCTIONS CAN
RESULT IN PERSONAL INJURY OR DEATH.
WARNING: ALWAYS DISCONNECT THE
VEHICLE'S BATTERY PRIOR TO
PERFORMING ANY TYPE OF WORK ON THE
HEATER ASSEMBLY. FAILURE TO FOLLOW
THESE INSTRUCTIONS CAN RESULT IN
PERSONAL INJURY OR DEATH.
WARNING: NEVER ATTEMPT TO REPAIR THE
HEATER ASSEMBLY OR ANY OF ITS
INTERNAL COMPONENTS. ALWAYS
PERFORM HEATER COMPONENT
REPLACEMENT IN ACCORDANCE WITH THE
SERVICE INFORMATION. FAILURE TO
FOLLOW THESE INSTRUCTIONS CAN
RESULT IN PERSONAL INJURY OR DEATH.
CAUTION: Always Perform The Heater
Pre-Test (In The Diagnostic Procedures) Prior
To Performing Any Other Test On The Heater
For The Test Result To Be Valid.
NOTE: Do not disconnect the vehicle's
battery or the heater's main power-supply
while the heater is in operation or in
run-down mode. Failure to follow these
instructions may result in excess emissions
from the heater.
NOTE: Failure to prime the Dosing Pump
after draining the fuel line will prevent heater
activation during the first attempt to start the
unit. This may also set a Diagnostic Trouble
Code (DTC) in the control unit's memory. Do
not perform the Dosing Pump Priming
Procedure if an attempt was made to start the
heater without priming the Dosing Pump
first. This will put excess fuel in the heater
module and cause smoke to emit from the
heater's exhaust pipe when heater activation
occurs.
NOTE: Waxed fuel can obstruct the fuel line
and reduce flow. Check for the appropriate
winter grade fuel and replace as necessary.
The Cabin Heater Assembly and Heater Booster
Assembly are supplemental type heaters designed
to pre-heat the engine's coolant in order to supply
the vehicle's occupants with heat prior to the engine
7
GENERAL INFORMATION

reaching operating temperature. The heater's con-
trol unit controls and monitors combustion opera-
tion through various inputs and outputs that are
contained inside the heater assembly. The supple-
mental heater connects to the vehicle's heater hoses
and uses a separate fuel supply line and fuel pump
that connects to the vehicle's fuel tank. Unlike the
Heater Booster, the Cabin Heater Assembly has an
integral coolant pump which allows heater opera-
tion without the vehicle's engine running. In addi-
tion, a programmable timer module can also be
added to this system. Neither the Cabin Heater
Assembly nor the Heater Booster Assembly are
connected to the CAN Bus. Communication be-
tween the heater's control unit and the DRBIIIt
occurs through the Diagnostic Link Connector
(DLC) via a K-Line.
3.3.2.2 VENTING THE HEATER'S EXHAUST
WARNING: NEVER OPERATE THE HEATER
IN AN ENCLOSED AREA THAT DOES NOT
HAVE EXHAUST VENTILATION FACILITIES.
ALWAYS VENT THE HEATER'S EXHAUST
WHEN OPERATING THE HEATER. FAILURE
TO FOLLOW THESE INSTRUCTIONS CAN
RESULT IN PERSONAL INJURY OR DEATH.
WARNING:
ALLOW THE HEATER ASSEMBLY TO
COOL BEFORE PERFORMING A COMPONENT
INSPECTION/REPAIR/REPLACEMENT. FAILURE
TO FOLLOW THESE INSTRUCTIONS CAN
RESULT IN PERSONAL INJURY OR DEATH.
CAUTION: When using a powered exhaust
ventilation system, do not attach the exhaust
ventilation hose directly to the heater's
exhaust pipe. Too much suction can prevent
heater operation.
When using a powered exhaust ventilation sys-
tem, affix the ventilation hose to the heater's ex-
haust pipe or to the vehicle in such a manor that the
end of the ventilation hose remains approximately
three inches away from the end of the heater's
exhaust pipe.
When using a non-powered exhaust ventilation
system, affix the ventilation hose directly to the
heater's exhaust pipe.
3.3.2.3 SYSTEM DIAGNOSTICS
CAUTION: Always Perform The Heater
Pre-Test (In The Diagnostic Procedures) Prior
To Performing Any Other Test For The Test
Result To Be Valid.
Fault detection is through stored Diagnostic
Trouble Codes (DTCs). DTCs are displayed by the
DRBIIIt. The heater's control unit will store up to
five DTCs in its memory. If the control unit detects
a new fault in the system, one that is not already
stored in its memory, it will clear the oldest of the
five stored DTCs, and it will store the new fault's
DTC. If the control unit detects a reoccurrence of a
stored fault, it will overwrite that fault's DTC with
the most recent occurrence.
DIAGNOSTIC TIPS
SENSOR VALUES
Operating Voltage
The normal range for the Operating Voltage is from
10 volts to 15 volts. The value indicates the voltage
at the heater 's Fused B+ terminal.
Heating Capacity
The normal range for the heating capacity is from
0% to 100%. The value indicates the momentary
output of the auxiliary heater in % of the maximum
output.
Coolant Temperature
The value indicates the current coolant tempera-
ture.
Flame Sensor Resistance
The normal range for the Flame Sensor is from 750
ohms to 2270 ohms. The value indicates the mo-
mentary resistance of the Flame Sensor.
INPUT/OUTPUT STATUS
Dosing Pump
A status of9ON9indicates that the Dosing Pump is
operational. A status of9OFF9indicates the Dosing
Pump is not operational.
Glow Pin
A status of9ON9indicates that the Glow Pin is
energized. A status of9OFF9indicates the Glow Pin
is not energized.
Combustion Fan
A status of9ON9indicates that the Combustion Fan
is operational. A status of9OFF9indicates the
Combustion Fan is not operational.
Circulation Pump
A status of9ON9indicates that the Circulation
Pump is operational. A status of9OFF9indicates the
Circulation Pump is not operational.
Front End Blower
A status of9ON9indicates that the Blower Motor is
operational. A status of9OFF9indicates the Blower
Motor is not operational.
8
GENERAL INFORMATION

the A-pillar. The SKREEM receives radio messages
from the RKE transmitter (fob) and sends com-
mands via the RKE Interface circuit to the CTM. If
the vehicle is equipped with VTSS, the Security
System Module will be connected in series between
the SKREEM and the CTM.
Confirmation of the RKE Lock/Unlock state is
accomplished via the turn signals. When the vehicle
is locked via RKE the turn signals will flash three
times. When it is unlocked via RKE, the turn
signals will flash one time. If the vehicle has been
unlocked via RKE and no door is opened within 40
seconds, the entire vehicle will be locked again
automatically.
If a transmitter (fob) is operated more than 255
times in succession beyond the range of the receiver
(SKREEM), the RKE portion of the key will become
inoperative. In order to put it back in synchroniza-
tion it will be necessary to have ALL the other
transmitters that are used with this vehicle avail-
able and follow the following procedure:
1. Cycle the ignition on and off 2 times within 6
seconds (leave in off position).
2. Press the lock or unlock button of the disabled
transmitter within 3 seconds of turning the
ignition off.
3. Press any button (lock or unlock) 3 more times
within 6 seconds.
4. Wait 10 seconds.
5. Press any button of ALL other transmitters
belonging to this vehicle at least once within
the next 20 seconds.
For problems related to the Immobilizer function
of the SKREEM, see Service Information.
3.5.3 AUTO DOOR LOCKS
Whenever the engine is started, the CTM receives
a message to lock all doors except the drivers door.
This is accomplished through the D+ Relay. The D+
Relay is controlled by the Instrument Cluster which
receives a command from the ECM that the engine
is running. This relay supplies power to the CTM
(for auto locking), the daytime running lamps and
the rear window defogger.
3.5.4 ACCIDENT RESPONSE
The CTM is hardwired to the Airbag Control
Module through the Enhanced Accident Report
Driver circuit. Anytime the vehicle airbags are
deployed, the CTM will unlock all doors and a
9Crash9DTC will be stored in memory. The door
locks will be inoperative until that code is cleared. If
the vehicle is severly jarred, but not enough to
deploy the airbags, it is possible that the DTC could
be set and therefore the door locks would be inop-
erable. Whenever the door locks are not opera-tional, use the DRBIII and check DTC's . If the code
9ACM has unlocked the doors9appears, use the
DRBIII and erase it.
3.6 VEHICLE THEFT SECURITY SYSTEM
(VTSS)
The Security System Module (SSM) is located
under the driver's seat. The SSM communicates
with the DRBIII over the K-line. If equipped the
Vehicle Theft Security System will monitor the
following:
²door jamb switches
²hood ajar switch
²ignition switch
²interior of the vehicle for movement
²longitudinal and transverse movement of the
vehicle
²rear defogger grids for glass breakage
²trailer connector
To arm the system the hood and all of the doors
must be closed when the vehicle is locked with the
RKE transmitter or with the use of the key in the
driver door. If the key is used, it must be held in the
lock position for 2 seconds. When the system is first
activated, the hazard lamps will flash 3 times. Also
with the system armed, the Towing/Intrusion Sen-
sor On/Off Switch indicator will flash to indicate an
armed system. To disarm the system use the RKE
or the driver door lock cylinder. Unlocking and
opening one of the other doors with the system
armed will trip the vehicle theft security system.
Interior monitoring is done by the use of an
Intrusion Sensor located in the front headliner and
with one or two sensors in the ceiling of the cargo
area depending on how the vehicle is equipped.
Monitoring of the interior of the vehicle will begin
after the system has been armed for 30 seconds. The
on/off switch located on the instrument panel can be
used to turn off this feature with the ignition switch
in either the Locked/Off or ACC position. The vehi-
cle tow-monitoring feature can also be switched off
using this switch. Re-locking the vehicle a second
time will reactivate these features.
If a trailer is connected to the vehicle when the
system is armed, the SSM will sense a resistance
change on the turn signal circuits if the trailer
harness becomes disconnected and will trip the
alarm.
Tripping the vehicle theft security system will
cause the hazard lamps to flash and the siren to
sound at 30-second intervals. The siren is equipped
with it's own self-contained battery. In the event the
vehicle's battery power is disconnected the siren
will continue to sound on it's own.
10
GENERAL INFORMATION

WARNING:REASSEMBLE ALL COMPONENTS
BEFORE ROAD TESTING A VEHICLE. DO NOT
TRY TO READ THE DRBIIITSCREEN OR
OTHER TEST EQUIPMENT DURING A TEST
DRIVE. DO NOT HANG THE DRBIIITOR OTHER
TEST EQUIPMENT FROM THE REARVIEW
MIRROR DURING A TEST DRIVE. HAVE AN
ASSISTANT AVAILABLE TO OPERATE THE
DRBIIITOR OTHER TEST EQUIPMENT.
FAILURE TO FOLLOW THESE INSTRUCTIONS
CAN RESULT IN PERSONAL INJURY OR
DEATH.
5.0 REQUIRED TOOLS AND
EQUIPMENT
DRBIIIt(diagnostic read-out box)
Jumper wires
Ohmmeter
Voltmeter
Test Light
8310 Airbag System Load Tool
8443 SRS Airbag System Load Tool
9001 R F Detector
6.0 GLOSSARY OF TERMS
ABSantilock brake system
ACMairbag control module
ACTactuator
AECMairbag electronic control module
(ACM)
ASDMairbag system diagnostic module
(ACM)
AT Cautomatic temperature control
CABcontroller antilock bake
CANcontroller area network
CHMcabin heater module
CPAconnector positive assurance
CTMcentral timer module
DABdriver airbag
DCHAdiesel cabin heater assist (cabin
heater)
DLCdata link connector
DTCdiagnostic trouble code
DRdriver
EBLelectric back lite (rear window de
fogger)
ECMengine control module
GCCGulf Coast Countries
HBMheater booster module
HVACheater ventilation, air conditioning
ICinstrument cluster
MICmechanical instrument cluster
RSMRain Sensor Module
SAshifter assembly
SKREEMsentry key remote entry module
SSMsecurity system module
TCMtransmission control module
13
GENERAL INFORMATION