Chrysler Voyager. Manual — part 147

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 “learns” 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 low
side 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.

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

15

GENERAL INFORMATION

allow the rear defrost to operate in the RUN posi-
tion. This circuit is electronically controlled and
continuously monitored for malfunctions.

3.8.3

ELECTRICAL INPUTS

Headlamp battery supplies 1 & 2 — 12 volt
input on pins 1 and 2. Battery supply voltage for
switching headlamp circuits only.

Module battery supply — 12 volt input on pin 9.
Battery supply voltage for all other FCM opera-
tions.

Power ground — Ground source on pin 8 for all
FCM operations.

Ignition switch RUN or START position status
— 12 volt input on pin 37. Allows the FCM to
determine the ignition switch status for related
FCM operations.

Ignition switch START only status — 12 volt
input on pin 19. Allows the FCM to discriminate
between RUN/START input and START for related
FCM operations.

PCI Bus — Approximately 7.5 volt input on pin 22.
Allows the FCM to communicate with other mod-
ules on the vehicle bus.

Stop lamp Switch status — 12 volt input on pin
44. Provides for brake shift interlock function.

Horn Switch — Ground input on pin 17. Primary
means for engaging the horn.

Back-up switch — Ground input on pin 39. Input
is converted to a PCI Bus status message for use by
other modules.

Wiper park switch — Ground 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 — Ground input to
pull-up on pin 18. Ground is switched into the
circuit when washer bottle fluid level is low.

Brake fluid level switch — Ground input to
pull-up on pin 36. Ground is switched into the
circuit when brake fluid level is low.

Ambient temperature sensor — Resistive 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 — 12 volt input on pin
21. Used to determine if right park lamp circuit is
operating properly.

Left park lamp outage — 12 volt input on pin 41.
Used to determine if left park lamp circuit is
operating properly.

Battery IOD — 12 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 — 12 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
the CPA is not properly engaged, a voltage on pin 38
will be interpreted as an unseated connector and a
fault will set.

Flash programming voltage — 20 volt input on
pin 42. When a DRBIII

t is connected and the

proper flash reprogramming sequence is selected,
the 20 volt signal will be applied through pin 42.

3.9

HEATING & A/C SYSTEM

3.9.1

AUTOMATIC TEMPERATURE
CONTROL (ATC)

CAUTION: Automatic Temperature Control
(ATC) Modules with software versions 41 and
0A used in 2001 and 2002 RS/RG vehicles are
NOT compatible with software versions 13
and 0F used in 2003 RS/RG vehicles. Do NOT
install an ATC Module with software version
41 or 0A in a 2003 RS/RG vehicle or an ATC
Module with software version 13 or 0F in a
2001 or 2002 RS/RG vehicle. Use the DRBIII

T

to verify which version software the ATC
Module is using by selecting Body Systems,
Automatic Temperature Control, and then
selecting Module Display.

3.9.1.1

SYSTEM AVAILABILITY

EXCEPT EXPORT

•

The ATC system is a Three-Zone Air Conditioning
System.

EXPORT

•

Two different types of systems are currently
available for these vehicles.

c

Dual-Zone Air Conditioning System for all
vehicles with 2.4L and 2.5L engines and all
SWB vehicles with 3.3L engines.

c

Three-Zone Air Conditioning System for all
LWB vehicles.

16

GENERAL INFORMATION

CABIN HEATER, EXPORT WITH DIESEL ENGINE

•

A Cabin Heater is used in conjunction with the
ATC system. The Cabin Heater is designed to
supply the vehicle’s occupants with heat prior to
the engine reaching operating temperature. For
additional information on this system, refer to
Cabin Heater under General Information and
Diagnostic Procedures in this manual.

3.9.1.2

SYSTEM CONTROLS

The ATC Module:

•

is fully addressable with the DRBIII

t.

•

communicates over the Programmable Commu-
nication Interface Multiplex System (PCI) Bus.

•

provides an A/C request over the PCI Bus to the
Powertrain Control Module (PCM) when com-
pressor operation is desired.

•

for exports with diesel engines, provides a Cabin
Heater activation request over the PCI Bus to the
Front Control Module (FCM) when conditions are
favorable for Cabin Heater operation.

•

uses input from the evaporator temperature sen-
sor to prevent evaporator freeze up while main-
taining optimum cooling performance.

•

uses input from infrared (I/R) sensors, which
measure surface temperature, to maintain occu-
pant comfort levels.

c

The I/R sensors are mounted in the instru-
ment panel center bezel.

•

can be operated in a manual mode.

•

provides a blower relay on request over the PCI
Bus to the Front Control Module (FCM) when
blower operation is desired.

•

controls front blower operating speed, providing
10 speeds in manual mode and infinite speeds in
automatic mode.

•

controls rear blower operating speed, providing
10 speeds in manual mode and infinite speeds in
automatic mode.

c

The separate front and rear Blower Motor
Controllers operate as follows: When blower
operation is desired, the Blower Motor Con-
troller provides a 10.0 volt signal to the ATC
Module over a control circuit. The ATC Mod-
ule provides a variable duty cycle ground to
the 10.0 volt signal based on input from the
blower switch. When the blower switch is set
to LO speed, the ATC Module provides a short
duty cycle (less time grounding the signal
voltage). As higher blower speeds are re-
quested, the ATC Module increases the duty
cycle (more time grounding the signal volt-
age). When the blower switch reaches HI

speed, the duty cycle increases to where the
signal pattern is almost a flat line (with brief
voltage spikes).

•

controls the front and rear electronic door actua-
tors’ operation.

c

A simplified control system for operation of
the mode, recirculation, and temperature con-
trol actuators provides positive positioning
without the complexity of feedback from posi-
tion sensors. The ATC Module knows the
number of operating actuator revolutions re-
quired for full door travel as well as the
number of actuator commutator pulses per
revolution. Using these parameters, the ATC
Module runs the actuator for the number of
commutator pulses that correspond to the
desired door position. To maintain accuracy,
the system recalibrates itself periodically at
known zero and full travel conditions.

•

activates and deactivates the Rear ATC Switch.

The Rear ATC Switch (Three-Zone Only):

•

provides desired rear blower speed input to the
ATC Module.

•

provides desired rear blend and mode door posi-
tion input to the ATC Module.

The Dual-Zone ATC system uses:

•

two front, two-wire electronic blend door actua-
tors.

•

one front, two-wire electronic mode door actuator.

•

one, two-wire electronic recirculation door actua-
tor.

The Three-Zone ATC system uses:

•

two front, two-wire electronic blend door actua-
tors.

•

one front, two-wire electronic mode door actuator.

•

one, two-wire electronic recirculation door actua-
tor.

•

one rear, two-wire electronic blend door actuator.

•

one rear, two-wire electronic mode door actuator.

System Relays

•

The Integrated Power Module (IPM) houses and
provides power to the A/C Clutch Relay, Front
Blower Motor Relay, and Rear Blower Motor
Relay.

3.9.1.3

SYSTEM REVISIONS

Revisions to the 2003 ATC system include:

•

all new version 13 (Two-Zone) and 0F (Three-
Zone) system software.

17

GENERAL INFORMATION

CAUTION: Automatic Temperature Control
(ATC) Modules with software versions 41 and
0A used in 2001 and 2002 RS/RG vehicles are
NOT compatible with software versions 13
and 0F used in 2003 RS/RG vehicles. Do NOT
install an ATC Module with software version
41 or 0A in a 2003 RS/RG vehicle or an ATC
Module with software version 13 or 0F in a
2001 or 2002 RS/RG vehicle. Use the DRBIII

T

to verify which version software the ATC
Module is using by selecting Body Systems,
Automatic Temperature Control, and then
selecting Module Display.

•

a Two-Zone HVAC system on select models.

•

a Cabin Heater used in conjunction with the ATC
system. For additional information on this sys-
tem, refer to The AC Cooldown Test, under 3.9.1.4
System Diagnostics in this General Information
section, and refer to Cabin Heater under General
Information and Diagnostic Procedures in this
manual.

•

deletion of the rear IR sensor.

3.9.1.4

SYSTEM DIAGNOSTICS

Fault detection is through active and stored Diag-
nostic Trouble Codes (DTCs)

•

DTCs are displayed by the DRBIII

t.

•

Active 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.

•

Stored DTCs are those which occurred in the
system since the ATC Module received the last
9clear diagnostic info9 message.

The AC Cooldown Test:

•

is actuated with the DRBIII

t.

•

checks A/C system performance based on evapo-
rator temperature sensor input.

•

forces the ATC to initiate the Cabin Heater Acti-
vation request when the vehicle is equipped with
a Diesel Cabin Heater Assist.

WARNING: DO NOT OPERATE THE DCHA IN
AN ENCLOSED AREA SUCH AS A GARAGE
THAT

DOES

NOT

HAVE

EXHAUST

VENTILATION FACILITIES. ALWAYS VENT
THE DCHA’s EXHAUST WHEN OPERATING
THE

DCHA.

REFER

TO

VENTING

THE

DCHA’s EXHAUST UNDER CABIN HEATER IN
THE GENERAL INFORMATION PORTION OF
THIS

SECTION

FOR

PROPER

EXHAUST

VENTING

INSTRUCTIONS.

FAILURE

TO

FOLLOW

THESE

INSTRUCTIONS

MAY

RESULT IN PERSONAL INJURY OR DEATH.

CAUTION: Do not activate the A/C Cooldown
Test with the engine off. Failure to follow
these manuals may result in internal
damage to the DCHA Heater Module.

c

The FCM monitors the PCI bus for the Cabin
Heater Activation request. The request car-
ries the status bit that the FCM requires to
activate its’ Cabin Heater Assist Control out-
put. 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 in-
put, it interprets this as an activation signal.

c

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 additional information, refer to
Cabin Heater under General Information and
Diagnostic Procedures in the manual.

•

will not run the air conditioning portion of this
test if ambient temperature is below 12°C (53°F).

c

The forced Cabin Heater activation will occur
even if the air conditioning portion of this test
fails to initiate because AC Cooldown test
criteria was not met. When activated, the
DCHA will operate for approximately seven
minutes. Three minutes to run and four min-
utes to purge.

•

will pass the air conditioning portion of this test
if the evaporator temperature drops 6.7°C (20°F)
within two minutes of starting this test.

•

messages (air conditioning related only) display
on the DRBIII

t after running this test.

c

These messages will clear after paging back
out of this test. Therefore, it is important to
note all of the AC Cooldown test messages
before doing so.

c

All Cabin Heater-related DTCs display under
Cabin Heater, Read DTCs.

•

will cause the DELAY and Snowflake VF seg-
ments on the ATC to flash for 162 seconds (RG
with DCHA only). If the air conditioning portion
of this test fails, the DELAY and Snowflake VF
segments will continue to flash until the vehicle
is driven more than three miles.

18

GENERAL INFORMATION