ignition CHRYSLER VOYAGER 2001 User Guide

section 7.0. This will direct you to the specific test(s)
that must be performed. Active diagnostic trouble
codes for the airbag system are not permanent and
will change the moment the reason for the code is
corrected. In certain test procedures within this
manual, diagnostic trouble codes are used as a
diagnostic tool.
3.1.9 ACTIVE CODES
The code becomes active as soon as the malfunc-
tion is detected or key-on, whichever occurs first. An
active trouble code indicates an on-going malfunc-
tion. This means that the defect is currently there
every time the airbag control module checks that
circuit or component. It is impossible to erase an
active code. Active codes automatically erase by
themselves when the reason for the code has been
corrected. With the exception of the warning lamp
trouble codes or malfunctions, when a malfunction
is detected, the airbag lamp remains lit for a mini-
mum of 12 seconds or as long as the malfunction is
present.
3.1.10 STORED CODES
Airbag codes are automatically stored in the
ORC's memory as soon as the malfunction is de-
tected. The exception is the Loss of Ignition Run
Only code which is an active code only. A stored code
indicates there was an active code present at some
time. However, the code currently may not be
present as an active code, although another code
could be active. When a trouble code occurs, the
airbag warning indicator illuminates for 12 seconds
minimum (even if the problem existed for less than
12 seconds). The code is stored, along with the time
in minutes it was active, and the number of times
the ignition has been cycled since the problem was
last detected. The minimum time shown for any
code will be one minute, even if the code was
actually present for less than one minute. Thus, the
time shown for a code will be one minute, even if the
code was actually present for less than one minute.
Thus, the time shown for a code that was present
for two minutes 13 seconds, for example, would be
three minutes. If a malfunction is detected a diag-
nostic trouble code is stored and will remain stored.
When and if the malfunction ceases to exist, an
ignition cycle count will be initiated for that code. If
the ignition cycle count reaches 100 without a
reoccurrence of the same malfunction, the diagnos-
tic trouble code is erased and that ignition cycle
counter is reset to zero. If the malfunction reoccurs
before the count reaches 100, then the ignition cycle
counter will be reset and diagnostic trouble code
will continue to be a stored code. If a malfunction is
not active while performing a diagnostic test proce-
dure, the active code diagnostic test will not locatethe source of the problem. In this case, the stored
code can indicate an area to inspect. 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 AUDIO SYSTEM
The following radios are all on the PCI Bus
system - RBB, RBK, RAZ, RAD, RBT, and RBY. The
remaining radio also available, the RAS, is NOT on
the PCI Bus. The PCI Bus inputs into the radio are
used for VF dimming, remote steering wheel con-
trols and cabin EQ preference. PCI Bus outputs
from the radio are used for the Name Brand
Speaker (NBS) relay activation, as well as cabin EQ
preference.
The RBB and RBK radios have the capability of
containing multiple vehicle unique equalization
curves (cabin EQ preferences) within the radio.
These curves will reside in the radio's flash memory.
The radio is capable of storing up to 20 unique
equalization curves. The latent curves can be se-
lected via the Front Control Module transmitting a
PCI Bus message to the radio in response to a radio
request for equalization message. Upon receipt of a
valid equalization select message response, the ra-
dio will switch to output the corresponding equal-
ization curve.
All the radios, except the RAS, are capable of
displaying faults and allowing certain actuation
tests through the use of the DRBIIIt. When at-
tempting to perform PCI Bus diagnostics, the first
step is to identify the radio in use in the vehicle.
When trouble shooting output shorts or ªoutputº
error messages, the following applies:
On radios without an external amplifier, the term
output refers to the path between the radio and the
speaker. This type of circuit can be monitored all
the way through the speaker connections by the
radio assembly. When the radio displays a shorted
output DTC with this type of system, the speaker,
radio, or wiring could be at fault. The output DTC
could refer to the front or rear output or a left or
right output. The reason for the difference is the
pairing of the output sections of the radio. Some are
paired left and right, others are paired front and
rear.
On radios with an external amplifier, the term
ªoutputº refers to the circuit between the radio
connector and the amplifier. The radio is capable of
monitoring only this portion and can tell nothing
about the circuit between the amplifier and the
speakers. Consequently, a shorted output DTC on
7
GENERAL INFORMATION

this type of system would only refer to this circuit.
A faulty speaker could not cause this DTC.
3.2.1 REMOTE RADIO CONTROLS
These radios can be controlled via remote radio
switches (optional). These switches are located on
the back side of the steering wheel. They control
mode, preset, seek up, seek down, volume up and
volume down functions.
These functions are inputs to the Body Control
Module and can be read with the DRBIIItunder
ªbody computerº. The switches are a multiplexed
signal to the BCM. The radio control MUX circuit is
a 5 volt line that is pulled to ground through
different value resistors built into the switches.
This causes a voltage drop to be seen by the BCM
and it sends a specific message to the radio on the
PCI Bus circuit. The radio then responses to the
message.
This circuit is fairly simple to troubleshoot. The
circuit must be complete from the switches in the
steering wheel to the BCM. The ground must be
complete so that the switches can cause the voltage
drop for the BCM to see. The circuit passes through
the clockspring so continuity through this devise
must be verified.
3.2.2 CD CHANGER
The new in-dash CD Changer is designed to fit
into the existing cubby bin in the center stack. This
new cartridge-less CD Changer is controlled by
your radio, and allows you to individually load up to
four discs at a time. However, due to its compact
design, the CD Changer can only carry out one
operation at a time. For example, you can not load
a new disc while playing another at the same time.
Each operation happens sequentially.
The radio unit installed with your system pro-
vides control over all features of the CD Changer
with the exception of the CD load and eject func-
tions, which are controlled by buttons located on the
front of the CD Changer. The radio also supplies the
power, ground, PCI Bus, left and right speaker
output thru a single DIN cable. All features you
would expect, such as Disc Up/Down, Track Up/
Down, Random and Scan are controlled by the
radio, which also displays all relevant CD Changer
information on the radio display.
The CD Changer contains a Load/Eject button
and an indicator light for each of the four disc
positions. The individual light indicates whether a
CD is currently loaded in that particular chamber of
the CD Changer. Pressing the individual Load/Eject
button for a particular chamber will eject a disc
currently present in that chamber. If the chamber iscurrently empty, actuating the Load/Eject button
will position that chamber to receive and load a new
disc in that chamber.
3.3 BODY CONTROL MODULE
The body control module (BCM) supplies vehicle
occupants with visual and audible information and
controls various vehicle functions. To provide and
receive information, the module is interfaced to the
vehicle's serial bus communications network (PCI).
This network consists of the powertrain control
module (PCM), the engine control module (ECM) -
diesel only, the transmission control module (TCM),
the mechanical instrument cluster (MIC), the front
control module (FCM), the occupant restraint con-
troller (ORC), the compass/mini-trip (CMTC), the
electronic vehicle information center (EVIC), the
controller antilock brake (CAB), the HVAC control
module (ATC & MTC), the power sliding door (Left
& Right) modules (PSD), the power liftgate module
(PLG), the Audio system, the side impact airbag
control (left & right) modules (SIACM), the memory
seat/mirror module (MSMM), the RKE/thatcham
alarm module and the sentry key immobilizer mod-
ule (SKIM). The BCM is operational when battery
power is supplied to the module.
The body control module provides the following
features:
²Power Door Locks
²Automatic Door Lock
²Door Lock Inhibit
²Central Locking (with VTSS Only)
²Battery Protection
²The BCM will automatically turn off all exterior
lamps after 3 minutes and all interior lamps after
15 minutes after the ignition is turned off, if they
are not turned off by the driver.
²Chime
²Compass/Minitrip Support
²Interior Lighting (Courtesy/Reading Lamps)
²BCM Diagnostic Reporting
²Electronic Liftgate Release (with Power Door
Locks)
²Exterior Lighting
²Power Folding Mirrors
²Remote Radio Controls
²Headlamp Time Delay (with/without Autohead-
lamps)
²Automatic Headlamps (with electrochromatic
mirror)
²Illuminated Entry
²Fade to Off
8
GENERAL INFORMATION

This feature dims the interior lighting (courtesy
lamps) gradually if the BCM does not receive any
new inputs that would cause the interior lamps to
remain on.
²PWM Instrument Panel Dimming
²Door Lock Inhibit
This feature disables the door lock functions if the
key is in the ignition and either front door is ajar.
Pressing the RKE lock/unlock button under these
conditions, result in normal lock/unlock activation.
²Power Sliding Door Switch Inputs
The BCM has 4 switch inputs for the power
sliding door feature: Located in the overhead con-
sole are the Left and Right side sliding door
switches to activate either or both sliding doors
under the proper conditions. Also are B-Pillar
switches located on the Left and Right B-pillar
posts.
²Power Liftgate Switch Input
The BCM has 1 Liftgate switch input located in
the overhead console
²Power Lockout Switch Input
The BCM has 1 Lockout switch that when en-
abled will disable the B-Pillar sliding door switches
from activating either sliding door when depressed.
When replacing a body control module there are 2
modules available, a Base and a Midline. The
Midline controller is used on vehicles that have
Power Door Locks. If a vehicle is equipped with the
Vehicle Theft Security System, the midline control-
ler becomes a premium when the theft feature is
enabled.
NOTE: DO NOT SWAP THE BODY CONTROL
MODULE BETWEEN VEHICLES OR BODY
CONTROL MODULES OFF THE SHELF.
Engineering does not recommend that service,
dealers or the plant swap Body Control Modules
(BCM) between vehicles or off the shelf. The BCM
has internal diagnostic capability that assists in
diagnosing the system. When an ªOpenº or a
ªShortº circuit exists, the diagnostic tool can be
used to read the BCM codes. The codes are very
descriptive in identifying the appropriate feature
that has faulted.
3.4 CHIME WARNING SYSTEM
The BCM monitors the door/liftgate ajar
switches, multifunction switches, headlight switch,
ignition switch, PCI bus, and the diagnostic tool to
perform various chime operations. The BCM uses a
low-side driver to control the chime located in the
cluster.
The chime system provides the Driver with warn-
ing chimes for:
²Seat belt
²Exterior lights on
²Key-in Ignition
²Key-in Accessory
²Engine temperature critical
²Low washer fluid
²Turn signals on
²Dome light on
²Low oil pressure
²Any warning lamp announcement
²High-speed warning Gulf Coast Countries (GCC)
only
The output sound intensity of the chime is ap-
proximately 72 decibels.
3.4.1 CHIME PRIORITY
The following list indicates the priority of the
chime when more than one chime is active at the
same time:
²Seat belt warning
²High-speed warning Gulf Coast Countries (GCC)
only
²Turn signal on
²Chime request
²Warning lamp announcement
The cluster is responsible to set priority on all
warning lamp announcement chimes.
3.4.2 CHIME ON CONDITIONS
The following is a list of the chime warnings and
when they will sound.
Driver 's Seat
belt Unbuckled:Sounds for approximately 662
seconds when the igntion is turned
on and driver 's seat belt is not
buckled, as a reminder to the
driver to buckle the seat belt.
Exterior Lights
On:Ignition is in the lock position,
the driver door is ajar, and the
headlight switch is left in any
position, other than auto or off.
The chime will sound as a warn-
ing to the driver until one of the
above conditions is removed or
until the battery protection time
of 3 minutes has expired.
Key-In Ignition: Ignition is in the lock position,
driver door is ajar and the key is
in the ignition. The chime will
sound until one of the above con-
ditions is removed or until the
battery protection time of 15 min-
utes has expired.
9
GENERAL INFORMATION

Turn Signal On: When the BCM detects a turn
signal input continuously for
1.0mile/0.6km and the vehicle
speed is greater than 15 mph/
24kph, the chime will sound until
the specific turn signal is can-
celled.
Dome Lights On: Ignition is in the lock position,
driver door ajar, and the dome
light switch is left in the on
position. The chime will sound
until one of the above conditions
is removed or until the battery
protection time of 15 minutes has
expired.
Low Oil Pres-
sure:The chime will sound when the
engine is operating and the oil
pressure drops below 4psi/27.5kPa.
Engine
Temperature
Critical:The chime will sound when the
engine is operating and the cool-
ant temperature exceeds 252ÉF/
122Cor 234É/112C(diesel).The
chime is continuous at 257ÉF/
125C and will chime for 4 min-
utes and stop if the temperature
drops below 255ÉF/123C.
Low Washer
FluidThe chime will sound when the
washer fluid drops below a spe-
cific level.
Warning Lamp
Announcement:A chime will sound to alert the
driver to scan the instrument
panel to see which warning lamp
is illuminated. The door/liftgate
ajar warning lamp will appear
without a chime if the vehicle is
running and a door or the liftgate
is opened. A chime will sound if
the door or liftgate is still open
and the vehicle speed is greater
than 4mph/6kph.
High-speed
warning Gulf
Coast Countries
(GCC) onlyThe chime will sound, acting as a
warning to the driver that the
vehicle speed has exceed
75mph62/120kph63.3.4.3 WARNING LAMP ANNOUNCEMENT
Low Fuel Lamp: The cluster will request a single
chime after the indicator is illu-
minated.
Volt Lamp: The cluster will request a single
chime after the indicator is illu-
minated.
Oil Pressure
Lamp:The cluster will request a single
chime after illuminating the in-
dicator above 450rpm vehicle op-
eration.
Headlight Out
Lamp:The cluster will request a single
chime after the indicator is illu-
minated.
Liftgate Ajar
Lamp:The BCM determines when to
chime for liftgate ajar.
Fasten Seat Belt
Lamp:The BCM will request five chimes
from the MIC when the ignition
is turned to the unlock/run/start
positions if the driver seat belt is
not buckled.
Check Engine
Lamp:The cluster will request a single
chime after the indicator is illu-
minated.
Low Washer
Fluid Lamp:The cluster will request a single
chime after the indicator is illu-
minated.
Engine Tempera-
ture Lamp:The cluster will request a single
chime when the indicator is first
illuminated at 252ÉF/122C.
3.4.4 OTHER CHIME ON CONDITIONS
Bulb Check: The chime will sound three times
during bulb check.
Programming of
an Additional
Key Fob:A double cluster chime will sound,
which signals that the program
mode has been initiated.
Programming for
Rolling Door
Locks:When the programming has been
completed, a single tone from the
chime system, will occur.
10
GENERAL INFORMATION

3.7.6 EXTERIOR LIGHTING BATTERY
SAVER
The BCM monitors the status of, and controls, the
Park Lamps, Headlamps and Fog Lamp relays. If
any exterior lamps are left ON after the ignition is
turned OFF, the BCM will turn them OFF after 3
minutes.
3.7.7 AUTO HEADLAMPS
This feature is available on vehicles equipped
with both the Electrocromatic Mirror (ECM) and
the Compass/Mini-Trip Computer (CMTC). When
the BCM detects a day/night signal from the CMTC,
an ECM is present and Auto Headlamp mode is
selected.
3.8 FRONT CONTROL MODULE
The Front Control Module (FCM) is an electrical
control and interface center located in the engine
compartment. When it is mated to the Power Dis-
tribution Center (PDC), it is referred to as the
Intelligent Power Module (IPM). The IPM, with its
fuses and relays provides power and signal distri-
bution throughout most of the vehicle. The FCM
receives both hard wire and digital electronic inputs
from the vehicle electrical system through the PDC.
Based on these inputs and the ignition switch
position, it provides direct power feeds and relay
control to some of the vehicles' most critical electri-
cal systems.
The Front Control Module provides the following
features:
Controlled power feeds:
²Front airbag system
²Side airbag system
²Headlamp power
²EATX module power (4 speed only)
²Front washer motor
²Rear washer motor
²Brake shift interlock system
Relay controls:
²Fog lamp relay (when equipped)
²Park lamp relay
²Front wiper on relay
²Front wiper high/low relay
²Accessory relay
²Horn relay
²Front & rear blower relay
²Name brand speakers (NBS) relay
²Electronic back light (EBL) run only relay
²Cabin heater relayElectrical inputs:
²Headlamp battery supplies1&2
²Module battery supply
²Power ground
²Ignition switch RUN or START position status
²Ignition switch START only status
²PCI Bus
²Stop lamp switch
²Horn switch
²Back-up switch
²Wiper park switch
²Washer fluid level switch
²Brake fluid level switch
²Ambient temperature sensor
²Right park lamp outage
²Left park lamp outage
²Battery IOD
²Battery (+) connection detection
²Flash reprogramming voltage
3.8.1 CONTROLLED POWER FEEDS
Front airbag system
The FCM provides power to the Occupant Re-
straint Control (ORC) system through two ªfuse-
lessº circuits (ORC RUN/START, and ORC RUN
only). These circuits are electronically controlled
and continuously monitored for malfunctions.
Power is supplied while the ignition switch is in the
RUN and START positions on pin 48 of the FCM
connector, and in the RUN only position on pin 29.
Side airbag system
The FCM provides power to the Side Impact
Airbag Control Module (SIACM) system through
one ªfuselessº circuit. This circuit is electronically
controlled and continuously monitored for malfunc-
tions. Power is supplied in the ignition RUN and
START positions on pin 28 of the FCM connector.
Headlamp power
The headlamp switch is a direct input to the
BCM. The BCM sends a PCI Bus message to the
FCM informing it of a headlamp switch status
change. The FCM then turns on power to the
headlamps through four ªfuselessº circuits. These
circuits are electronically controlled and continu-
ously monitored for malfunctions. Power is supplied
to each filament in a separate circuit (RH low on pin
6, RH high on pin 4, LH low on pin 3 and LH high
on pin 5). For vehicles equipped with Daytime
Running Lamps (DRL), the FCM electronically
steps down the headlamp voltage to provide the
desired illumination.
13
GENERAL INFORMATION

EATX power
The electronic automatic 4 speed transmission
module is powered when the ignition switch is in
the UNLOCK, RUN or START positions. This cir-
cuit is electronically controlled and continuously
monitored for malfunctions. Power is supplied
through pin 27 of the FCM connector.
Front washer motor
The front washer switch is a direct input to the
BCM. The BCM sends a PCI Bus message to the
FCM informing it of a request to wash. The front
washer motor is then powered through low side
control inside the FCM. This circuit is electronically
controlled and continuously monitored for malfunc-
tions. In addition, the FCM electronically protects
the washer motor from system voltages higher than
16 volts by automatically switching off the low side
circuit. The low side circuit is connected to pin 45 in
the FCM connector.
Rear washer motor
The rear washer switch is a direct input to the
BCM. The BCM sends a PCI Bus message to the
FCM informing it of a request to wash. The rear
washer motor is then powered through low side
control inside the FCM. This circuit is electronically
controlled and continuously monitored for malfunc-
tions. In addition, the FCM electronically protects
the washer motor from system voltages higher than
16 volts by automatically switching off the low side
circuit. The low side circuit is connected to pin 46 in
the FCM connector.
Brake shift interlock system
The brake shift interlock solenoid receives power
from both high side and low side controls inside the
FCM. The high side control is on the same circuit as
the EATX module power, and the low side control
comes through pin 47 of the FCM connector. The
solenoid is controlled by the low side driver when
the brake pedal is pressed. Both circuits are contin-
uously monitored for malfunctions.
3.8.2 RELAY CONTROLS
Fog lamp relay
The fog lamp switch is a direct input to the BCM.
The BCM sends a PCI Bus message to the FCM
informing it to turn on the fog lamp relay. The fog
lamp relay is then powered through low side control
on pin 33 of the FCM. This circuit is electronically
controlled and continuously monitored for malfunc-
tions. Fog lamp functionality is not equipped on all
vehicles. The FCM ªlearnsº that the vehicle is
equipped with fog lamps by reading the BCM PCI
Bus message.
Park lamp relay
The park lamp switch is a direct input to the
BCM. The BCM sends a PCI Bus message to the
FCM informing it to turn on the park lamp relay.
The park lamp relay is then powered through lowside control on pin 13 of the FCM. This circuit is
electronically controlled and continuously moni-
tored for malfunctions.
Front wiper on relay
The front wiper switch is a direct input to the
BCM. The BCM sends a PCI Bus message to the
FCM informing it to turn on the front wiper on
relay. The front wiper on relay is then powered
through low side control on pin 14 of the FCM. This
circuit is electronically controlled and continuously
monitored for malfunctions.
Front wiper high/low relay
The front wiper switch is a direct input to the
BCM. The BCM sends a PCI Bus message to the
FCM informing it to turn on the front wiper high/
low relay. The relay switches power between the low
speed and high speed windings of the wiper motor.
The front wiper high/low relay is powered through
low side control on pin 34 of the FCM. This circuit is
electronically controlled and continuously moni-
tored for malfunctions.
Accessory relay
The accessory relay works in conjunction with the
FCM's power accessory delay feature to control the
operation of the radio, power windows, washer
motors, wiper motors and power outlet. The acces-
sory relay is turned on through low side control on
pin 35 of the FCM. This circuit is electronically
controlled and continuously monitored for malfunc-
tions. Depending on the ignition switch position,
the accessory relay will remain on or will time-out
and turn off. The accessory relay remains on in the
RUN and ACCY positions of the ignition switch. In
the UNLK and OFF positions, the relay will remain
energized for 45 seconds then turn off. During this
time-out period, if the driver or passenger doors are
opened, the relay will turn off immediately. While
the ignition switch is in the START position, the
relay will also drop-out, then resume operation.
Accessory relay operation is most noticeable by
observing the operation of the radio or blower
functions.
Horn relay
The horn relay operates through a direct wire
input to the FCM from the horn switch (FCM pin
17) , or a PCI Bus message from the BCM. The relay
responds to the horn switch, remote door lock and
VTA alarm functions. The horn relay is powered
through low side control on pin 10 of the FCM.
Under normal operating conditions, if the horn is
pressed for longer than 30 seconds, the FCM will
automatically deactivate the horn to prevent dam-
age to it. The FCM will re-activate control of the
relay after a 25 second cool-down period. This
circuit is electronically controlled and continuously
monitored for malfunctions.
14
GENERAL INFORMATION

Front and rear blower relay
The blower control switch is part of the Automatic
Temperature Control (ATC) or A/C-Heater Control
Module, (Manual Temp). When the blower switch is
turned on, the ATC or A/C-Heater Control Module
sends a PCI Bus message to the FCM. The front and
rear blower relay is then powered through low side
control on pin 30 of the FCM. The relay provides the
high side to the blower motor, and the blower speed
is governed through low side control in the ATC or
A/C-Heater Control Module. This circuit is electron-
ically controlled and continuously monitored for
malfunctions.
Name Brand Speakers (NBS) relay
The NBS relay operates through the vehicle bus
interface between the radio and the FCM. When the
radio is turned on, the radio sends a PCI Bus
message to the FCM. The NBS relay is then pow-
ered on through low side control on pin 11 of the
FCM. The relay supplies power to the amplified
speaker, and ground is supplied through the radio.
This circuit is electronically controlled and contin-
uously monitored for malfunctions.
Electronic Back Light (EBL) relay
The rear defrost switch is part of the Automatic
Temperature Control or A/C-Heater Control Module
(Manual Temp). When the ignition switch is in the
RUN position and the rear defrost switch is turned
on, the ATC or A/C-Heater Control Module sends a
PCI Bus message to the FCM. The EBL run only
relay is then powered through low side control on
pin 31 of the FCM. The relay provides the high side
to the rear window defrost grid, and ground is
attached to the vehicle body. The FCM will only
allow the rear defrost to operate in the RUN posi-
tion. This circuit is electronically controlled and
continuously monitored for malfunctions.
Cabin Heater Relay
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. 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 activation
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. For addi-
tional information, refer to Cabin Heater under
General Information and Diagnostic Procedures in
the manual.3.8.3 ELECTRICAL INPUTS
Headlamp battery supplies1&2Ð12 volt
input on pins 1 and 2. Battery supply voltage for
switching headlamp circuits only.
Module battery supply Ð12 volt input on pin 9.
Battery supply voltage for all other FCM opera-
tions.
Power ground ÐGround source on pin 8 for all
FCM operations.
Ignition switch RUN or START position status
Ð12 volt input on pin 37. Allows the FCM to
determine the ignition switch status for related
FCM operations.
Ignition switch START only status Ð12 volt
input on pin 19. Allows the FCM to discriminate
between RUN/START input and START for related
FCM operations.
PCI Bus ÐApproximately 7.5 volt input on pin 22.
Allows the FCM to communicate with other mod-
ules on the vehicle bus.
Stop lamp Switch status Ð12 volt input on pin
44. Provides for brake shift interlock function.
Horn Switch ÐGround input on pin 17. Primary
means for engaging the horn.
Back-up switch ÐGround input on pin 39. Input
is converted to a PCI Bus status message for use by
other modules.
Wiper park switch ÐGround input on pin 16.
Used to determine park placement of wipers. Also
used as feedback to FCM to determine correct
operating mode of wipers.
Washer fluid level switch ÐGround input to
pull-up on pin 18. Ground is switched into the
circuit when washer bottle fluid level is low.
Brake fluid level switch ÐGround input to
pull-up on pin 36. Ground is switched into the
circuit when brake fluid level is low.
Ambient temperature sensor ÐResistive input
to pull-up on pin 25. Corresponding voltage level is
converted to a PCI Bus message for use by other
modules on the bus.
Right park lamp outage Ð12 volt input on pin
21. Used to determine if right park lamp circuit is
operating properly.
Left park lamp outage Ð12 volt input on pin 41.
Used to determine if left park lamp circuit is
operating properly.
Battery IOD Ð12 volt input on pin 20. The FCM
enters a low power consumption mode when the
ignition is turned OFF. This low current draw
battery supply keeps the microprocessor function-
ing in the low power mode.
Battery (+) connection detection Ð12 volt
input on pin 38. The battery connection on the PDC
incorporates the use of an internal switch to deter-
mine if the connector is properly mated and the
Connector Positive Assurance (CPA) is engaged. If
15
GENERAL INFORMATION

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-
20
GENERAL INFORMATION

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.
21
GENERAL INFORMATION

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
22
GENERAL INFORMATION