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The DCHA assembly consists of a:
²combustion air fan assembly
²burner housing
²burner insert
²control unit/heat exchanger
²combustion chamber
²dosing pump
3.10.2.2 COMBUSTION AIR FAN
The combustion air fan assembly includes the:
²combustion air fan
²combustion air fan inlet
²fuel supply inlet
The combustion air fan delivers the air required
for combustion from the combustion air inlet to the
burner insert.
3.10.2.3 BURNER HOUSING
The burner housing includes the:
²coolant inlet
²coolant outlet
²exhaust outlet
The burner housing accommodates the burner
insert and is combined with the control unit/heat
exchanger as an assembly.
3.10.2.4 BURNER INSERT
The burner insert includes the:
²combustion pipe fuel cross section
²glow plug/flame sensor
Inside the burner insert fuel is distributed across
the combustion pipe fuel cross section. Combustion
of the fuel/air mixture takes place within the com-
bustion pipe to heat the exchanger. The glow plug/
flame sensor located in the burner insert ignites the
fuel/air mixture during heater start up. After heater
start up, the glow plug/flame sensor operates in the
flame sensor function. The glow plug/flame sensor
designed as an electrical resistor is located in the
burner insert opposite the flame side.
3.10.2.5 CONTROL UNIT/HEAT
EXCHANGER
The control unit/heat exchanger includes the:
²control unit
²temperature sensor
²overheat protection
²heat exchanger
²connector terminal
The control unit controls and monitors combus-
tion operation. The control unit is ventilated bymeans of a ventilation hose routed from the com-
bustion air collector compartment of the burner.
The heat exchanger transfers the heat generated by
combustion to the coolant circuit. The control unit/
heat exchanger and the burner housing are an
assembly and must not be disassembled.
The temperature sensor senses the coolant tem-
perature in the heat exchanger as an electrical
resistance. This signal is sent to the control unit for
processing.
The overheat protection, controlled by the tem-
perature resistor, protects the heater against undue
operating temperatures. The overheat protection
will switch the heater off if the water temperature
exceeds 105ÉC (221ÉF).
3.10.2.6 DOSING PUMP
The dosing pump is a combined delivery, dosing,
and shut-off system for the fuel supply of the heater.
The dosing pump receives its supply of fuel from the
vehicle's fuel tank.
3.10.3 OPERATION
3.10.3.1 ACTIVATION
When the ignition is in Run, the FCM monitors
the PCI bus for the Cabin Heater Activation re-
quest. The A/C ± Heater Control Module initiates
this request only when all conditions for Cabin
Heater activation are favorable (see below). The
request carries the status bit that the FCM requires
to activate its Cabin Heater Assist Control Output.
This output is a low side driver (coming from FCM
pin 15) which supplies a ground signal to the Cabin
Heater (pin 5). When the Cabin Heater receives this
ground signal input, it interprets this as an activa-
tion signal. The FCM low side driver is also capable
of diagnostic sensing. The driver will sense an open
circuit when the driver is off, and will sense a short
to voltage when the driver is on. The FCM will set
DTCs for both of these types of faults.
The DCHA will activate only when the:
²engine is running.
²coolant temperature is below 66ÉC (151ÉF).
²fuel tank has greater than 1/8 of a tank of fuel.
²Power switch on the A/C ± Heater Control Module
is on.
²Blend Control on the A/C ± Heater Control Mod-
ule is set above 95% reheat.
²Front Control Module (FCM) sees the Cabin
Heater Activation request that is bussed from the
A/C ± Heater Control Module.
When the DCHA starting sequence begins, the
glow plug and the combustion air fan are activated.
After 30 seconds, the fuel dosing pump begins oper-
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ating and the combustion air fan operation is sus-
pended for 3 seconds. Subsequently, the combustion
air fan speed is increased in two ramps within 56
seconds to nearly full load operation. After a stabi-
lization phase of 15 seconds, the combustion air fan
speed is again increased in a ramp within 50
seconds to nearly full load. After reaching full load
fuel delivery, the glow plug is deactivated and the
combustion air fan operation is increased to full
load. During the subsequent 45 seconds, as well as
in normal operation, the glow plug functions as a
flame sensor to monitor the flame condition. After
all these events, the automatically controlled heat-
ing operation starts.
In case of a no flame or a flame out condition, a
restart is automatically initiated. If the no flame
condition persists, fuel delivery is stopped and the
heater enters an error lockout mode with a run-
down of the combustion air fan. This will set one or
more DTCs in the DCHA Control's memory. If six
continuous attempts to start the heater fail due to
one or more faults in the DCHA system, the heater
enters a heater lockout mode. This will set DTC
B1813 along with any other fault(s) that the DCHA
Control identified.
3.10.3.2 HEATING
During the automatically controlled heating op-
eration, when the coolant temperature reaches
72ÉC (162ÉF), the heater will switch to a part load
operation. When the coolant temperature reaches
75ÉC (167ÉF) or if the heater runs for longer than 76
minutes the heater will switch to a control idle
period. If the coolant temperature drops to 71ÉC
(160ÉF) during a control idle period, the heater will
perform a regular starting sequence into full load
operation. A drop in coolant temperature to 65ÉC
(149ÉF) during part load operation will cause the
heater to switch to a full load operation.
3.10.3.3 DEACTIVATION
The DCHA will deactivate if the:
²engine is turned off.
²coolant temperature reaches 75ÉC (167ÉF).
²heater runs longer than 76 minutes.
²fuel tank has less than 1/8 of a tank of fuel.
²Power switch on the A/C ± Heater Control Module
is off.
²Blend Control on the A/C ± Heater Control Mod-
ule is set below 75% reheat.
When the heater is deactivated, the combustion
stops and a run-down sequence begins. During the
run-down sequence, the combustion air fan contin-
ues operation to cool down the heater. The fan is
automatically switched off after the run-down se-
quence is complete. The run-down time and thecombustion air fan speed depend on the heater
operating condition at the time of deactivation.
Run-down time is approximately 175 seconds when
deactivated in full load operation and approxi-
mately 100 seconds when deactivated in part load
operation.
3.10.4 DIAGNOSTICS
The DCHA is fully addressable with the DRBIIIt.
System tests include a Field Mode Test to activate
the DCHA for diagnostic testing purposes. The
DCHA Control will store up to three DTCs in its
memory. If the Controller detects a new fault in the
DCHA system, one that is not already stored in its
memory, it will clear the oldest of the three stored
DTCs, and it will store the new fault's DTC. If the
Controller detects a reoccurrence of a stored fault, it
will overwrite that fault's DTC with the most recent
occurrence.
3.11 INSTRUMENT CLUSTER
The Instrument Cluster receives and sends mes-
sages to other modules via the PCI bus circuit. The
indicator lamps will illuminate briefly for a bulb
check when the ignition is turned from off to run.
All of the gauges receive their information via the
PCI bus from the powertrain control module and
body control module.
The gauges and the LEDs are not individually
replaceable thereby requiring complete replace-
ment of the Instrument Cluster if a repair is neces-
sary. In the event that the Instrument Cluster loses
communication with other modules on the PCI bus,
the cluster will display ªno busº in the VF display.
The Trip/Reset button is used to switch the dis-
play from trip to total mileage. Holding the button
when the display is in the trip mode will reset the
trip mileage. This button is also used to put the
cluster in self-diagnostic mode. The odometer dis-
play uses blue-green vacuum fluorescent digital
characters.
On base vehicles, the Instrument Cluster has
three gauges: Speedometer, Fuel and Engine Cool-
ant Temperature. A red dot moves transversely
through openings in the Instrument Cluster face
(P-R-N-D-2-1) to indicate the gear selected.
With all other models, the Instrument Cluster
also includes a Tachometer and uses a vacuum-
fluorescent shift indicator.
The odometer display and door/liftgate ajar indi-
cators turn on when a door is opened to assist both
the customer and service technician to view the
odometer without turning the ignition on.
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On vehicles equipped with AutoStick, the display
includes an O/D OFF indicator that is illuminated
when the driver presses the Overdrive Off button
on the transaxle shifter.
3.11.1 INSTRUMENT CLUSTER SELF TEST
1. Depress and hold the Odometer Reset button.
2. Turn the ignition switch to the RUN/START
position.
3. Release the Odometer reset button.
The Instrument Cluster will illuminate all indi-
cators and step the gauges through several calibra-
tion points. Also, the odometer will display any
stored codes that may have set.
3.11.2 MESSAGE CENTER
The Message Center is located above the brow of
the Instrument Cluster. It houses the following
warning indicators: Check Engine/Service Engine
Soon, high beam, left and right turn signals, Secu-
rity Alarm Set, and low oil pressure. On base
models equipped with the three-speed transaxle,
these indicators appear in the face of the cluster.
The Security Alarm set indicator is a red circle.
Activation of Instrument Cluster indicators is
coordinated with indicators in the message center
and EVIC to avoid redundancy. A revised safety
standard now requires that the seat belt warning
lamp in the Instrument Cluster remain lit if the
driver seat belt is not buckled. A headlamp out ISO
indicator has been added to the Instrument Cluster
to alert the driver when a headlamp is not function-
ing.
3.12 INTERIOR LIGHTING
3.12.1 COURTESY LAMP CONTROL
The body controller has direct control over all of
the vehicle's courtesy lamps. The body computer
will illuminate the courtesy lamps under any of the
following conditions:
1. Any door ajar and courtesy lamp switch on the
headlamp switch is not in the dome off position.
2. The courtesy lamp switch on the headlamp
switch is in the dome on position.
3. A Remote Keyless Entry unlock message is re-
ceived.
4. Driver door unlocked with key (with VTSS only).
3.12.2 ILLUMINATED ENTRY
Illuminated entry will be initiated when the cus-
tomer enters the vehicle by unlocking the doors
with the key fob, or with the key if the vehicle is
equipped with vehicle theft alarm. Upon exiting thevehicle, if the lock button is pressed with a door
open, illuminated entry will cancel when the door
closes. If the doors are closed and the ignition
switch is turned on, the illuminated entry also
cancels. The illuminated entry feature will not
operate if the courtesy lamp switch is in the dome
off position.
3.12.3 INTERIOR LIGHTING BATTERY
SAVER
If any of the interior lamps are left on after the
ignition is turned off, the BCM will turn them off
after 8 minutes. To return to normal operation, the
courtesy lamps will operate after the dome lamp
switch or door ajar switch changes state. The glove
box and switched reading lamps require that the
ignition be turned to the on/acc position.
3.13 MEMORY SYSTEM
The memory system consists of power driver 's
seat, power mirrors and radio presets. The Memory
Seat/Mirror Module (MSMM) is located under the
driver 's seat. It receives input from the following:
driver 's manual 8-way seat switch, driver 's seat
position sensors, PCI bus circuits, and the power
mirror sensors. The module uses these inputs to
perform the following functions: position the driv-
er 's memory seat, both exterior mirrors (during
recalls), and send/receive the memory system infor-
mation over the PCI bus.
The Memory Set Switch is wired to the Body
Control Module (BCM). When a button (either #1 or
#2) is pressed on the set switch causes the to BCM
send a message to the MSMM which in turn sends
a motion status messages to the BCM. If the BCM
receives no motion from the MSMM it will send a
recall message to the MSMM and radio (once igni-
tion is in run or accessory). The MSMM will in turn
position the drivers seat, both mirrors along with
recalling the radio presets. If the drivers seat or
either exterior mirror is inoperative from its own
respective switches, use the service information
and schematic to diagnose the problem. This man-
ual addresses the memory problems only and it is
assumed there is not a basic component failure.
3.13.1 POWER SEAT
The memory power seat provides the driver with
2 position settings for the driver 's seat. Each power
seat motor is connected to the MSMM with two
motor drive circuits. Each circuit is switched be-
tween battery and ground. By being able to bi-
directionally drive the circuits, the MSMM controls
the movement of the motors based on input from
the power seat switch or from the position sensors
when performing a memory recall. Each motor
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contains a potentiometer to monitor the seat posi-
tion. To monitor the position of the motor, the
MSMM sends out a 5-volt reference on the sensor
supply circuit. The sensor is grounded back to the
module on a common ground circuit. Based on the
position of the sensor, the MSMM monitors the
voltage change through the sensor on a separate
signal circuit.
The MSMM stores the input value of each of the
four seat potentiometers in memory when the sys-
tem requests a set. The driver can initiate a mem-
ory recall, using either the door mounted memory
switch or the RKE transmitter (if the remote linked
to memory feature is enabled via the EVIC). When
initiated, the MSMM adjusts the four seat sensors
(by using the motors) to match the memorized seat
position data.
For safety, the memory seat recall is disabled by
the MSMM when the vehicle is out of park position
or if the speed is not zero. Any obstruction to seat
movement over a 2-second delay will cause the seat
to stop moving in which case a stalled motor would
be detected by the MSMM and the corresponding
seat output would be deactivated. However, if the
object obstructing the seat is removed, the seat will
function normally again.
3.13.2 MEMORY MIRRORS
Each outside mirror contains vertical and hori-
zontal bi-directional drive positioning motors and
position sensors. The MSMM provides a 5-volt
reference on the signal circuit to each position
sensor. The sensors share a common ground circuit.
The MSMM monitors the position of the mirror
motors by measuring the voltage on each signal
circuit. When a memory position is set, the MSMM
monitors and stores the position of the outside
mirrors. The MSMM adjusts the mirrors to the
appropriate positions when a memory recall mes-
sage is received from the RKE or is requested from
the memory set switch.
The power mirror switch during non-memory
operation operates both mirrors independently of
the MSMM.
3.14 OVERHEAD CONSOLE
3.14.1 COMPASS/MINI-TRIP COMPUTER
(CMTC)
The compass/mini-trip computer is located in the
overhead console. It displays to the driver the
direction the vehicle is traveling and the current
outside temperature, as well as the following trav-
eler navigational information: average fuel econ-
omy (AVG ECO), distance to empty (DTE), instan-
taneous fuel economy (ECO), elapsed time (ET),and trip odometer (ODO). The information needed
for the CMTC functions is received over the PCI bus
from other modules.
3.14.2 ELECTRONIC VEHICLE
INFORMATION CENTER (EVIC)
The Electronic Vehicle Information Center
(EVIC) includes all the same functions and is lo-
cated in the same area as the Compass/Mini-Trip
Computer, but it adds a number of warning mes-
sages. Also, the EVIC messages are spelled out on
the screen, for example, DISTANCE TO EMPTY,
where the Mini-Trip Computer displays only shows
DTE.
If the compass/mini-trip computer or EVIC has
been replaced, it may be necessary to reset the
calibration.
3.14.3 SETTING THE COMPASS
The compass/mini-trip computer and EVIC are
self-calibrated and requires no adjustment. The
word CAL will be displayed to indicate that the
compass is in the fast calibrating mode. CAL will
turn off after the vehicle has gone in three complete
circles without stopping, in an area free of magnetic
disturbance.
If the module displays the temperature while the
compass is blank or shows a false reading, the
vehicle must be demagnetized. See the service man-
ual for the proper procedure.
If the compass still goes blank after the vehicle is
demagnetized, the compass/mini-trip/EVIC module
must be replaced.
3.14.4 SETTING THE VARIANCE
Variance is the difference between magnetic
north and geographic north. To determine the vari-
ance for the area you are in, refer to the following
zone map provided. The number shown for your
area is the variance number for your area.
1. Set the compass/mini-trip computer (CMTC) to
compass/temperature mode.
2. Press and hold down the RESET button for 5
seconds.NOTE:If the button is held for 10
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seconds instead of 5, the CMTC will set the
variance to 8 and enter the fast calibration
mode.
3. The VAR light will come on and the last variance
setting will be displayed.
4. Press the STEP button to set the zone number.
5. Press the US/M button and resume normal op-
eration.
NOTE: Do not attach any magnetic device
such as a magnetic CB antenna to the
vehicle. This can cause the compass to give
false readings.
3.15 POWER DOOR LOCK SYSTEM
When the BCM receives input for a lock request
from a door lock switch, RKE or cylinder lock switch
(only with VTSS), it will turn the lock driver on for
a specified time of 375 msec. If the request is there
beyond 375 msec, the BCM considers the door lock
signal stuck. Once a door lock or unlock signal is
stuck for longer than 10 seconds, the BCM will set
a trouble code and the signal input is ignored until
the stuck condition disappears. The door lock
switches provide a variable amount of resistance
thereby dropping the voltage of the multiplexed
(MUX) circuit and the BCM will respond to that
command.
3.15.1 SLIDING DOOR MEMORY LOCK
When the BCM receives an input for a lock
request and a sliding door is open, the BCM will
turn on the lock driver as described above, and will
turn it on again when all sliding doors are closed.
NOTE: If the BCM receives an unlock input before
a sliding door is closed, this will cancel the memory
lock.
3.15.2 DOOR LOCK INHIBIT
When the key is in the ignition and in any
position and either front door is open, the door lock
switches LOCK functions are disabled. The UN-
LOCK functions are still functional. This protects
against locking the vehicle with the keys still in the
ignition. The RKE key fob will still lock the doors as
usual. This allows the driver to lock the vehicle with
the engine running for warm up.
3.15.3 AUTOMATIC DOOR LOCKS
This feature can be enabled or disabled by using
either the DRBIIItor the customer programming
method. When enabled all the doors will lock when
the vehicle reaches a speed of 18 MPH (29 KMH)
and all the doors are closed. If a door is opened and
the vehicle slows to below 18 MPH (29 KMH), thedoor locks will operate again once all doors are
closed and the speed is above 15 MPH (24 KMH).
3.15.4 REMOTE KEYLESS ENTRY (RKE)
The body control module interfaces with the RKE
module via a one-way serial bus interface. The RKE
module is not on the PCI bus. The RKE module
sends a 0-5 volt pulse width signal to the BCM
depending on which button on the transmitter was
pressed. The BCM controls the door lock/unlock
functions and the arming/disarming of the Vehicle
Theft Security System (if equipped) and the activa-
tion of illuminated entry. The BCM will also send
the appropriate messages to the Power Sliding
Doors and Power Liftgate modules. The Intelligent
Power Module (IPM) activates the park lamps,
headlamps, and horn for horn chirp when sent the
appropriate message from the BCM as received
from the RKE transmitter. When a one-button
press is made for unlock, both driver side doors will
unlock and the front and rear turn signal will flash.
When a second press is initiated (within 5 seconds
of the first) both passenger doors will unlock and all
four turn signals will flash.
The RKE module is capable of retaining up to 4
individual access codes (4 transmitters). If the
PRNDL is in any position except park, the BCM will
ground the interface thereby disabling the RKE.
The 2 button transmitter will have 2-CR2016
batteries in series. The 5 button transmitter will
have 1-CR2016 battery. The minimum battery life
should be approximately 4.7 years based on 20
transmissions a day at 84ÉF (25ÉC). Using the
DRBIIItand selecting RKE FOB Test can test the
transmitter.
The RKE module can be programmed via the
DRBIIItor the customer programming method.
The BCM will only allow programming mode to be
entered when the ignition is in the on position, the
PRNDL is in park position, and the VTSS (if
equipped) is in the disarmed mode.
3.16 POWER FOLDING MIRRORS
The power folding mirrors are powered to two
positions: folded and unfolded. The driver may
choose fold or unfold with a switch that is located on
the right side of the steering column. The folding
mirror switch grounds a sense wire that comes from
the Body Control Module when it is placed in the
fold position. The mirrors will move to the position
designated by the switch whether the ignition
switch is the On or Off position and both front doors
are closed. When the Power Folding Mirror switch
is left in the fold position during a vehicle exit the
mirrors will automatically unfold then refold after
both front doors are closed. This is to prevent mirror
contact with either front door when opened. When
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opening either front door, the Body Control Module
will unfold the mirrors in the following manner
depending on which front door is opened. If the
driver door is opened, only the driver side mirror
will unfold. If the passenger door is opened, both
mirrors will unfold. The passenger mirror is pre-
vented from unfolding when the driver 's door is
opened by the Passenger Folding Mirror Relay,
which opens the driver circuit to the passenger side
mirror.
3.17 POWER LIFTGATE SYSTEM
3.17.1 POWER LIFTGATE
The power liftgate (PLG) system is activated
through the use of the following: remote keyless
entry (RKE), overhead console switches, outside
liftgate handle switch or the DRBIIIt. These inputs
are hardwired to the body control module (BCM)
and can be monitored with a diagnostic tool. The
BCM will send the message via PCI bus to the
power liftgate module (PLGM). The liftgate must be
in the full open or full closed position to operate.
Once the BCM sends a button activation message to
the PLGM, the module shall read all inputs, out-
puts and vehicle conditions to determine whether it
shall open, close or inhibit the PLG operation. Once
the PLGM determines the vehicle conditions are
safe for operation, the PLGM will initiate a chime
for 2 seconds prior to the liftgate activation and 2
seconds during the open or close cycle.
During an opening or closing cycle, the PLGM can
detect an obstacle present should it meet sufficient
resistance by the hall effect sensors (integrated in
the gear motor assembly GMA).
During an open cycle, multiple liftgate activa-
tions (RKE, overhead console, B pillar) are ignored
until the liftgate reaches the full open position.
However, during a close cycle, a 2nd liftgate activa-
tion (RKE, overhead console, B pillar) will reverse
the liftgate to the full open position.
If the engine is cranked during a power open/close
the PLG will pause then resume after engine crank-
ing. In addition, if the vehicle is placed in gear
during an open cycle, the PLG shall reverse direc-
tion and begin closing. If the vehicle is placed in
gear during a closing cycle, the PLG shall continue
closing until fully closed. If the outside handle is
activated during an open cycle, the PLG will become
a full manual liftgate. If the outside handle is
activated during a close cycle, the PLG shall reverse
direction of travel to the full open position.
3.17.2 DIAGNOSTIC FEATURES
The PLG can be flashed on vehicle via PCI bus
with a DRBIIItdiagnostic tool. The DRBIIItcanread all inputs, actuate all outputs, read module
information, and read diagnostic trouble codes. As a
reminder, some DTC's can be set during normal
PLG operation.
3.17.3 SYSTEM INHIBITORS
1. Battery voltage too high or too low (above 16V,
below 9.5V)
2. Vehicle in gear
3. Vehicle speed > 0 mph/km/h
4. Outside temperature too high, above 143ÉF
(62ÉC) or too low, below -12ÉF (-24ÉC).
5. O/H console lockout will inhibit the B pillar
switches only.
6. Liftgate locked will inhibit all interior switches
from opening (overhead console). A locked lift-
gate can be power closed.
7. Pinch Sensor switch stuck shall inhibit the
power close feature.
3.18 POWER SLIDING DOOR SYSTEM
3.18.1 POWER SLIDING DOOR
The Power Sliding Door (PSD) system is acti-
vated through the use of the following: Remote
Keyless Entry (RKE), overhead console switches, B
pillar switches or the DRBIIIt. These inputs are
hardwired to the body control module (BCM) and
can be monitored with a diagnostic tool. The BCM
will send the message via PCI bus to the power
sliding door module (PSDM). The sliding door must
be in the full open or full closed position to operate.
Once the BCM sends a button activation message to
the PSDM, the module shall read all inputs, out-
puts and vehicle conditions to determine whether it
shall open, close or inhibit the PSD operation.
During an opening or closing cycle, the PSDM can
detect an obstacle present should it meet sufficient
resistance by the hall effect sensors (integrated in
the drive motor).
During an open cycle, multiple door activations
(RKE, overhead console, B pillar) are ignored until
the door reaches the full open position. However,
during a close cycle, a 2nd door activation (RKE,
overhead console, B pillar) will reverse the door to
the full open position.
If the engine is cranked during a power open/close
the PSD will pause then resume after engine crank-
ing. In addition, if the vehicle is placed in gear
during an open cycle, the PSD shall reverse direc-
tion and begin closing. If the vehicle is placed in
gear during a closing cycle, the PSD shall continue
closing until fully closed.
If the inside or outside handle is activated during
an open or close cycle, the PSD will become a full
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manual sliding door. When the child lock out switch
is on, the B pillar switches are disabled.
There is only one part number for the power
sliding door module (PSDM). The driver sliding
door harness has an additional ground circuit which
will identify it as the driver side. This eliminates
the need for a left and a right side module.
3.18.2 DIAGNOSTIC FEATURES
The PSDM can be flashed on vehicle via PCI bus
with a DRBIIItdiagnostic tool. The DRBIIItcan
read all inputs, actuate all outputs, read module
information, and read diagnostic trouble codes. As a
reminder, some DTC's can be set during normal
PSD operation.
3.18.3 SYSTEM INHIBITORS
1. Battery voltage too high or too low (above 16V,
below 9.5V)
2. Vehicle in gear
3. Vehicle speed > 0 mph/km/h
4. Child locks enabled inhibit the B pillar switch
operation
5. O/H console lockout will inhibit the B pillar
switches
6. Doors locked will inhibit all interior switches
from opening (Overhead Console, B Pillar). A
locked sliding door can be power closed.
3.19 REAR WINDOW DEFOG/HEATED
MIRROR/FRONT WIPER DE-ICE
The defroster button located on the HVAC control
controls the rear window defogger, heated side view
mirrors and front wiper de-icer grid. In addition the
front wiper de-ice function is turned on when front
defog/defrost mode is selected.
When the defroster button is pushed, the HVAC
control sends a bus message over the PCI bus to the
Front Control Module (FCM) which controls the
Rear Window Defogger relay. The defroster LED
will illuminate when the defroster function is on.
The defroster will function for 10 minutes or can be
cycled off sooner by pressing the defroster button
again. The front wiper de-icer grid receives its 12
volts from the accessory relay through fuse 11 and
the HVAC control module supplies the grid ground.
3.20 VEHICLE THEFT SECURITY SYSTEM
3.20.1 BASE ALARM SYSTEM
The Vehicle Theft Security System (VTSS) is part
of the Body Control Module (BCM). The BCM
monitors the vehicle doors, liftgate, hood, and theignition for unauthorized operation. The alarm ac-
tivates by sounding the horn, flashing the head-
lamps and the VTSS indicator lamp. The VTSS does
not prevent engine operation, this is done with the
Sentry Key Immobilizer Module (SKIM). Passive
arming occurs in one of two ways. Upon normal
vehicle exit by removing the ignition key, opening
the driver door, locking the doors with the power
lock, and closing the driver door, or by removing the
ignition key, opening the driver door, closing the
driver door, and locking the doors with the Remote
Keyless Entry (RKE) transmitter. The VTSS indi-
cator lamp will flash for approximately 15 seconds
during the arming process. If there is no interrup-
tion during the arming process, upon completion
the VTSS indicator lamp will flash at a slower rate.
When the BCM receives an input to trigger the
alarm, the BCM will control the outputs of the
headlamps, horn, and VTSS lamp for approxi-
mately 18 minutes.
Arming (Active and Passive)
Active arming occurs when the RKE transmitter
is used to lock the vehicle doors, whether the doors
are open or closed. The arming process is complete
only after all doors are closed.
Passive arming occurs when the ignition key is
removed, the driver door is opened, and the doors
are locked with the power door lock switch, and the
door is closed.
Disarming (Active and Passive)
Active disarming occurs when the RKE transmit-
ter is used to unlock the vehicle doors. This disarm-
ing will also halt the alarm once it has been acti-
vated.
Passive disarming occurs upon normal vehicle
entry (unlocking driver door with the key). This
disarming will also halt the alarm once it has been
activated.
Tamper Alert
The VTSS tamper alert will sound the horn three
times upon disarming to indicate a tamper condi-
tion has occurred.
Manual Override
The system will not arm if the doors are locked
using the manual lock control or if the locks are
actuated by an inside occupant after the doors are
closed.
Diagnosis
For complaints about the Vehicle Theft Alarm
triggering on its own, use the DRBIIItand read the
Last VTSS Cause status.
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GENERAL INFORMATION
Page 56 of 4284

NOTE: A POWERTRAIN CONTROL MODULE
FROM A VEHICLE EQUIPPED WITH A
VEHICLE THEFT SECURITY SYSTEM
CANNOT BE USED IN A VEHICLE THAT IS
NOT EQUIPPED WITH A VEHICLE THEFT
SECURITY SYSTEM IF THE VTSS INDICATOR
LAMP COMES ON AFTER IGNITION ON AND
STAYS ON, THE PCI BUS COMMUNICATION
WITH THE POWERTRAIN CONTROL
MODULE HAS POSSIBLY BEEN LOST.
3.20.2 THATCHAM ALARM SYSTEM
The Thatcham Alarm Module monitors the vehi-
cle doors, liftgate, hood and the interior of the
vehicle for unauthorized operation. The vehicle
doors, liftgate, and hood use ajar switches as inputs
to the BCM to indicate their current status. The
interior of the vehicle is secured by the use of
Intrusion Sensors. The Intrusion Sensors are used
as inputs to the RKE/Thatcham Alarm Module to
report any motion in the interior of the vehicle. The
alarm activates by sounding the siren, flashing the
hazard lamps, and the VTSS Indicator Lamp.
Arming
Before arming, all doors, liftgate, and the hood
must be completely closed. The system can then be
armed by following a normal exit sequence, of
opening the door and then locking the doors with
the door lock switch and then closing the door. The
system can also be armed by opening the door,
closing the door and then locking the doors with the
RKE transmitter.
Disarming
To disarm the alarm system, the RKE transmit-
ter is used. The RKE transmitter will unlock the
vehicle doors and disarm the alarm system. The
RKE transmitter can also be used to halt the alarm
once it has been activated.
3.21 WIPER SYSTEM
3.21.1 FRONT WIPER
The front wiper/washer system consists of the
following features: lo-hi-speed, mist wipers, inter-
mittent wipers and wipe after wash. The front
wiper system is only active when the ignition switch
is in the RUN/ACC position. The vehicle operator
selects the front wiper function using the front
wiper switch (a resistive multiplexed stalk switch)
which is integral to the Multi-Function Switch. The
front wiper switch is hardwired to the Body Control
Module (BCM). Upon receiving a wiper switch sig-
nal, the BCM sends a PCI Bus message to the Front
Control Module (FCM). The FCM controls the ON/OFF relay, the HIGH/LOW relay and the front and
rear washer pump motors.
The Wiper system utilizes the BCM to control the
on/off and hi/low relays for the low and hi speed
wiper functions, intermittent wiper delay as the
switch position changes, pulse wipe, wipe after
wash mode and wiper motor functions. The BCM
uses the vehicle speed input to double the usual
delay time below 10 MPH (6 KPH).
3.21.2 SPEED SENSITIVE INTERMITTENT
WIPE MODE
There are 5 individual delay time settings with a
minimum delay of 1.7 seconds to a maximum of 18.4
seconds. When the vehicle speed is under 10 MPH
(6 KPM), the delay time is doubled, providing a
delay range of 3.4 seconds to 36.8 seconds.
3.21.3 PULSE WIPE
When the wiper is in the off position and the
driver presses the wash button for more than .062
seconds, but less than .5 seconds, 2 wipe cycles in
low speed mode will be provided.
3.21.4 PARK AFTER IGNITION OFF
Because the wiper relays are powered from the
battery, the BCM can run the wipers to park after
the ignition is turned off.
3.21.5 WIPE AFTER WASH
When the driver presses the wash button for over
.5 seconds and releases it, the wiper will continue to
run for 2 additional wipe cycles.
3.21.6 REAR WIPER
The rear wiper/washer system consists of the
following features: mist wipers, intermittent wipers
and wipe after wash. The rear wiper system is only
active when the ignition switch is in the RUN/ACC
position. The vehicle operator selects the rear wiper
function using one of the three buttons on the dash
mounted rear wiper switch. The rear wiper switch
is hardwired to the Body Control Module (BCM).
Upon receiving a wiper switch signal, the BCM
provides 12 volts to the rear wiper motor. Rear
washer occurs when the BCM receives a rear
washer switch ON input. The BCM sends a PCI Bus
message to the FCM requesting rear washer on.
The FCM activates the rear washer by providing a
ground for the rear washer motor.
3.21.7 SPEED SENSITIVE INTERMITTENT
WIPE MODE
The delay setting of the rear wiper system is
based solely on the vehicle speed. The delay time is
27
GENERAL INFORMATION