2002 CHRYSLER CARAVAN service

INSTALLATION
(1) Push bulb into switch.
(2) Connect wire harness to switch.
(3) Push switch into instrument panel.
(4) Close glove box door.
(5) Reconnect the battery negative cable.
LIFTGATE LAMP
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Using a flat bladed tool, pry lamp from trim
panel (Fig. 3).
(3) Disconnect wire harness connector from lamp.
(4) Pry off lens and remove bulb.
INSTALLATION
(1) Install bulb and snap lens into place.
(2) Reconnect wire harness connector to lamp.
(3) Position lamp onto trim panel and snap into
place.
(4) Reconnect battery negative cable.
READING LAMP
REMOVAL
The front reading lamps are incorporated into the
overhead console. If the reading lamps require
replacement, the overhead console must be replaced.
(Refer to 8 - ELECTRICAL/OVERHEAD CONSOLE -
REMOVAL). The rear reading lamps are incorporated
into the assist handle. If the rear reading lamps
require replacement, the assist handle must be
replaced. (Refer to 23 - BODY/INTERIOR/ASSIST
HANDLE - REMOVAL). The bulbs can be serviced
separately.
(1) Disconnect and isolate the battery negative
cable.
(2) Using a flat bladed tool, pry off the lamp lens
(Fig. 4), (Fig. 5).
Fig. 3 LIFTGATE LAMP
1 - LIFTGATE LAMP
2 - WIRE HARNESS
Fig. 4 OVERHEAD CONSOLE
1 - LAMP LENS
2 - OVERHEAD CONSOLE
RSLAMPS/LIGHTING - INTERIOR8L-27
GLOVE BOX LAMP SWITCH (Continued)
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from Fahrenheit to Celsius by selecting the desired
U.S./Metric option from the customer programmable
features. The displayed temperature is not an instant
reading of conditions, but an average temperature. It
may take the temperature display several minutes to
respond to a major temperature change, such as driv-
ing out of a heated garage into winter temperatures.
When the ignition switch is turned to the Off posi-
tion, the last displayed temperature reading stays in
the electronic control modules (CT, CMTC, EVIC)
memory. When the ignition switch is turned to the
On position again, the electronic module will display
the memory temperature for one minute; then update
the display to the current average temperature read-
ing within five minutes.
The temperature function is supported by an ambi-
ent temperature sensor. The sensor is mounted out-
side the passenger compartment near the front and
center of the vehicle, and is hard wired to the Front
Control Module (FCM). The FCM sends temperature
status messages to the module over the J1850 PCI
data bus circuit.
Following are general descriptions of the major
components used in the overhead console. Refer to
Wiring Diagrams for complete circuit schematics.
OPERATION
Refer to the vehicle Owner's Manual for specific
operation of each overhead console and its systems.
DIAGNOSIS AND TESTING - OVERHEAD
CONSOLE
If the problem with the overhead console is an
inaccurate or scrambled display, refer toSelf-Diag-
nostic Testbelow. If the problem with the overhead
console is incorrect Vacuum Fluorescent Display
(VFD) dimming levels, use a DRB IIItscan tool and
the proper Diagnostic Procedures manual to test for
the correct dimming message inputs being received
from the Body Control Module (BCM) or Front Con-
trol Module (FCM) over the J1850 Programmable
Communications Interface (PCI) data bus circuit. If
the problem is a no-display condition, use the follow-
ing procedures. For complete circuit diagrams, refer
toOverhead Consolein the Wiring Diagrams sec-
tion of the service manual.
(1) Check the fused B(+) fuse in the integrated
power module. If OK, go to Step 2. If not OK, repair
the shorted circuit or component as required and
replace the faulty fuse.
(2) Check for battery voltage at the fused B(+) fuse
in the integrated power module. If OK, go to Step 3.
If not OK, repair the open fused B(+) circuit to the
fused B(+) fuse in the integrated power module as
required.(3) Check the fused ignition switch output (run/
start) fuse in the integrated power module. If OK, go
to Step 4. If not OK, repair the shorted circuit or
component as required and replace the faulty fuse.
(4) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run/start) fuse in the integrated power mod-
ule. If OK, go to Step 5. If not OK, repair the open
fused ignition switch output (run/start) circuit to the
ignition switch as required.
(5) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the overhead console. Check for continuity
between the ground circuit cavity of the roof wire
harness connector for the electronics module and a
good ground. There should be continuity. If OK, go to
Step 6. If not OK, repair the open ground circuit to
ground as required.
(6) Connect the battery negative cable. Check for
battery voltage at the fused B(+) circuit cavity of the
roof wire harness connector for the electronics mod-
ule. If OK, go to Step 7. If not OK, repair the open
fused B(+) circuit to the fused B(+) fuse in the inte-
grated power module as required.
(7) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run/start) circuit cavity of the roof wire har-
ness connector for the electronics module. If OK,
refer toSelf-Diagnostic Testlater this group for
further diagnosis of the electronics module and the
J1850 PCI data bus circuit. If not OK, repair the
open fused ignition switch output (run/start) circuit
to the fuse in the integrated power module as
required.
SELF-DIAGNOSTIC TEST
A self-diagnostic test is used to determine that the
electronics module is operating properly, and that all
the J1850 PCI data bus messages are being received
for initial operation. Initiate the self-diagnostic test
as follows:
(1) With the ignition switch in the Off position, on
Electronic Vehicle Information Center (EVIC) and
Compass Mini-Trip Computer (CMTC) equipped vehi-
cles simultaneously depress and hold theSTEP and
the RESET buttons. On Compass Temperature
Module (CT) equipped vehicles depress theC/T and
the US/M push buttons.
(2) Turn the ignition switch to the On position.
(3) Following completion of these tests, the elec-
tronics module will display one of the following mes-
sages:
a.Pass Self Test (EVIC only), PASS (CT,
CMTC)- The electronics module is working properly.
b.Failed Self Test (EVIC only), FAIL (CT,
CMTC)- The electronics module has an internal fail-
8M - 2 MESSAGE SYSTEMSRS
OVERHEAD CONSOLE (Continued)
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ure. The electronics module is faulty and must be
replaced.
c.Failed J1850 Communication (EVIC only),
BUS (CT, CMTC)- The electronics module is not
receiving proper message input through the J1850
PCI data bus circuit. This can result from one or
more faulty electronic modules in the vehicle, or from
a faulty PCI data bus. The use of a DRB IIItscan
tool and the proper Diagnostic Procedures manual
are required for further diagnosis.
NOTE: If the compass functions, but accuracy is
suspect, it may be necessary to perform a variation
adjustment. This procedure allows the compass
unit to accommodate variations in the earth's mag-
netic field strength, based on geographic location.
Refer to Compass Variation Adjustment in the Ser-
vice Procedures section of this group.
NOTE: If the compass reading displays dashes, and
only ªCALº appears in the display, demagnetizing
may be necessary to remove excessive residual
magnetic fields from the vehicle. Refer to Compass
Demagnetizing in the Service Procedures section of
this group.
STANDARD PROCEDURE
STANDARD PROCEDURE - READING/
COURTESY LAMP REPLACEMENT
(1) Open hood, disconnect and isolate the negative
battery cable remote terminal from the remote bat-
tery post.
(2) Remove the reading/courtesy lamp lens. Using
a trim stick, gently pry the forward edge of the read-
ing/courtesy lamp lens outward.
(3) Remove the reading/courtesy lamp socket from
the overhead console. Rotate the reading/courtesy
lamp socket one quarter turn counter clockwise.
(4) Remove the lamp and socket assembly.
(5) Reverse the above procedure to install.
STANDARD PROCEDURE - COMPASS
CALIBRATION
CAUTION: Do not place any external magnets, such
as magnetic roof mount antennas, in the vicinity of
the compass. Do not use magnetic tools when ser-
vicing the overhead console.
The electronic compass unit features a self-cali-
brating design, which simplifies the calibration pro-
cedure. This feature automatically updates the
compass calibration while the vehicle is being driven.This allows the compass unit to compensate for small
changes in the residual magnetism that the vehicle
may acquire during normal use. If the compass read-
ings appear to be erratic or out of calibration, per-
form the following calibration procedure. Also, new
service replacement Electronic Modules (EVIC,
CMTC, CT) must have their compass calibrated
using this procedure. Do not attempt to calibrate the
compass near large metal objects such as other vehi-
cles, large buildings, or bridges; or, near overhead or
underground power lines.
NOTE: Whenever the compass is calibrated manu-
ally, the variance number must also be reset. Refer
to Compass Variation Adjustment in this group.
Calibrate the compass manually as follows:
(1) Turn the ignition switch to the On position. If
the compass/thermometer data is not currently being
displayed, momentarily depress and release the C/T
push button to reach the compass/thermometer dis-
play.
(2) On Electronic Vehicle Information Center
(EVIC) and Compass Mini-Trip Computer (CMTC)
equipped vehicles depress the Reset push button and
hold the button down until ªCALº appears in the dis-
play. This takes about ten seconds, and appears
about five seconds after ªVAR = XXº is displayed. On
Compass Temperature Module (CT) equipped vehicles
depress the C/T push button and US/M push button
down until ªCALº appears in the display. This takes
about ten seconds, and appears about five seconds
after ªVAR = XXº is displayed.
(3) Release the push button(s).
(4) Drive the vehicle on a level surface, away from
large metal objects and power lines, through three or
more complete circles at between five and eight kilo-
meters-per-hour (three and five miles-per-hour) in
not less than 48 seconds. The ªCALº message will
disappear from the display to indicate that the com-
pass is now calibrated.
NOTE: If the ªCALº message remains in the display,
either there is excessive magnetism near the com-
pass, or the unit is faulty. Repeat the calibration
procedure one more time.
NOTE: If the wrong direction is still indicated in the
compass display, the area selected for calibration
may be too close to a strong magnetic field. Repeat
the calibration procedure in another location.
RSMESSAGE SYSTEMS8M-3
OVERHEAD CONSOLE (Continued)
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ELECTRONIC VEHICLE INFO
CENTER
DESCRIPTION
The Electronic Vehicle Information Center (EVIC)
is a module located in the overhead console on some
models. The EVIC module features a large Vacuum
Fluorescent Display (VFD) screen for displaying
information, and back-lit push button switches
labeled C/T (compass/thermometer), RESET, STEP,
and MENU.
The EVIC module contains a central processing
unit and interfaces with other electronic modules in
the vehicle over the Programmable Communications
Interface (PCI) J1850 data bus circuit. The PCI data
bus circuit allows the sharing of sensor information.
This helps to reduce wire harness complexity, reduce
internal controller hardware, and reduce component
sensor current loads. At the same time, this system
provides increased reliability, enhanced diagnostics,
and allows the addition of many new feature capabil-
ities.
The EVIC ªMenuº push button provides the vehicle
operator with a user interface, which allows the
selection of several optional customer programmable
electronic features to suit individual preferences.
Refer toELECTRONIC VEHICLE INFORMA-
TION CENTER PROGRAMMINGin the Service
Procedures section of this group for more information
on the customer programmable feature options.
If the vehicle is equipped with the optional univer-
sal transmitter transceiver, the EVIC will also dis-
play messages and an icon indicating when the
universal transmitter transceiver is being trained,
which of the three transmitter buttons is transmit-
ting, and when the transceiver is cleared.
Data input for all EVIC functions, including VFD
dimming level, is received through the J1850 PCI
data bus circuit. The EVIC module uses its internal
programming and all of its data inputs to calculate
and display the requested data. If the data displayed
is incorrect, perform the self-diagnostic tests as
described in this group. If these tests prove inconclu-
sive, the use of a DRBIIItscan tool and the proper
Diagnostic Procedures manual are recommended for
further testing of the EVIC module and the J1850
PCI data bus circuit.
The EVIC module cannot be repaired, and is avail-
able for service only as a unit. This unit includes the
plastic module and display lens. If any of these com-
ponents is faulty or damaged, the complete EVIC
module must be replaced.
OPERATION
The EVIC has access to both non-switched and
ignition switched sources of battery current so that
some of its features remain operational at any time,
while others may only operate with the ignition
switch in the On position. When the ignition switch
is turned to the On position, the EVIC module VFD
will return to the last function being displayed before
the ignition was turned to the Off position.
The compass/thermometer display is the normal
EVIC display. With the ignition switch in the On
position, momentarily depressing and releasing the
C/T (compass/thermometer) push button switch will
cause the EVIC to return to the compass/thermome-
ter/trip computer display mode from any other mode.
While in the compass/thermometer/trip computer dis-
play mode, momentarily depressing and releasing the
Step push button will step through the available trip
computer display options.
The EVIC trip computer features several functions
that can be reset. The functions that can be reset
are: average fuel economy, trip odometer and elapsed
time. With the ignition switch in the On position and
with one of the functions of the trip computer that
can be reset currently displayed, depressing the
Reset push button twice within three seconds will
perform a global reset, and all of the trip computer
information that can be reset will be reset to zero.
With the ignition switch in the On position and the
function that is to be reset currently displayed,
momentarily depressing and releasing the Reset
push button once will perform a local reset, and only
the value of the displayed function will be reset to
zero. A global or local reset will only occur if the
function currently displayed is a function that can be
reset. The distance to service function can also be
reset using the local reset method, but it will reset
back to the Service Interval distance that is set in
the EVIC programmable features mode. Refer to
ELECTRONIC VEHICLE INFORMATION CEN-
TER PROGRAMMINGin the Service Procedures
section of this group for more information on setting
the Service Interval.
For more information on the features, control func-
tions and setting procedures for the EVIC module,
see the owner's manual in the vehicle glove box.
DIAGNOSIS AND TESTING - ELECTRONIC
VEHICLE INFORMATION CENTER
Electronic Vehicle Information Center (EVIC) data
is obtained from the Body Control Module (BCM) on
the J1850 Data Bus circuit. The EVIC will display
dashes (- -) for any of the screens it did not receive
the bus messages. The label corresponding to the
missing information will be lit. If no EVIC data is
displayed, check the J1850 Data Bus circuit commu-
8M - 6 MESSAGE SYSTEMSRS
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nications and the BCM. If the brightness level is
improper check the J1850 Data Bus circuit.
The DRB IIItis recommended for checking the
J1850 Data Bus circuit and the BCM. Perform the
EVIC self diagnosis before replacing the EVIC mod-
ule.
STANDARD PROCEDURE - ELECTRONIC
VEHICLE INFORMATION CENTER
PROGRAMMING
EVIC PROGRAMMING MODE
Some vehicles are equipped with a Electronic Vehi-
cle Information Center (EVIC) equipped overhead
console. The Electronic Vehicle Information Center
(EVIC) provides the vehicle operator with a user
interface, which allows the selection of several
optional customer programmable electronic features
to suit individual preferences. The EVIC must be
placed into its programming mode in order to view or
change the programmable features. To enter the
EVIC programming mode and to view or change the
selected programmable features options, proceed as
follows:
(1) Turn the ignition switch to the On position.
(2) Depress and release the Menu push button.
The first item in the programmable features menu
list will appear in the EVIC display.
(3) Momentarily depress and release the Menu
push button to step through the programmable fea-
tures list. Each programmable feature and its cur-
rently selected option will appear on the EVIC
display in the sequence shown in the Programmable
Features list that follows.
(4) Momentarily depress and release the Step push
button to step through the available options for the
programmable feature being displayed.
(5) The option that last appears in the display
with a programmable feature before exiting the pro-
gramming mode, becomes the newly selected pro-
grammable feature option.
(6) The EVIC exits the programming mode and
returns to its normal operating mode when the C/T
push button is depressed or when the end of the pro-
grammable features menu list is reached, whichever
occurs first.
PROGRAMMABLE FEATURES
NOTE: TIRE PRESSURE MONITORING (TPM) SYS-
TEM INFORMATION IS NOT COVERED IN THIS SEC-
TION OF THE SERVICE MANUAL. REFER TO THE
TIRES/WHEELS SECTION OF THIS MANUAL FOR
DETAILED TPM SYSTEM INFORMATION.²LANGUAGE?- The options include English,
Francaise, Deutsch, Italiana, or Espanol. The default
is English. All EVIC display nomenclature, including
the trip computer functions, warning messages and
the programmable features appear in the selected
language.
²DISPLAY U.S. OR METRIC?- The options
include U.S. and M. The default is U.S. This feature
toggles the trip computer temperature, fuel economy
and odometer display readings between U.S. and
metric units of measure. It also changes the odome-
ter display in the instrument cluster.
²SERVICE INTV. =- The options include from
1000 to 12000 kilometers in 1000 kilometer incre-
ments (2000 to 7500 miles in 500 mile increments).
The default is 12000 kilometers (7500 miles). The
selected distance becomes the interval at which the
Perform Service warning message will be displayed
by the EVIC. If a new distance is selected, a second
programmable feature appears,RESET SERVICE
DISTANCE?- The options include No and Yes. The
default is Yes. When Yes is selected, the accumulated
distance since the last previous Perform Service
warning message will be reset to zero because the
service interval has been changed. When No is
selected, the distance until the next Perform Service
warning message is reduced by the accumulated dis-
tance since the last previous message.
²USE FACTORY SETTINGS?- The options
include Yes and No. The default is Yes. When yes is
selected all the programmable features will return to
there defaults and the rest of the programmable fea-
tures will not be displayed. If No is selected the rest
of the programmable features will be displayed at
there default values. This feature will automatically
return to the Yes default under two conditions. First,
if no programmable features are changed from there
defaults. Second, if all the programmable features
equal there defaults.
²AUTO DOOR LOCKS?- The options include
Yes and No. The default is Yes. When Yes is selected,
all doors and the liftgate lock automatically when
vehicle speed reaches 25 kilometers-per-hour (15
miles-per-hour). If YES is selected, a second program-
mable feature appears,AUTO UNLOCK ON EXIT?
- The options again include Yes and No. The default
is No. When Yes is selected, following each Auto Door
Lock event all doors and the liftgate will automati-
cally unlock when the driver door is opened, if the
vehicle is stopped and the transmission gear selector
is in Park or Neutral. The Auto Door Unlock event
will only occur once following each Auto Door Lock
event.
²REMOTE UNLOCK- The options include
Driver Door 1st and All Doors. The default is Driver
Door 1st. When Diver Door 1st is selected, only the
RSMESSAGE SYSTEMS8M-7
ELECTRONIC VEHICLE INFO CENTER (Continued)
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NOTE: IF A NEW EVIC MODULE HAS BEEN
INSTALLED, THE COMPASS WILL HAVE TO BE
CALIBRATED AND THE VARIANCE SET. REFER TO
COMPASS VARIATION ADJUSTMENT AND COM-
PASS CALIBRATION IN THE SERVICE PROCE-
DURES SECTION OF THIS GROUP FOR THE
PROCEDURES.
COMPASS/MINI-TRIP
COMPUTER
DESCRIPTION
The Compass Mini-Trip Computer (CMTC) and
Compass Temperature (CT) computer are modules
located in the overhead console. Vehicles are
equipped with either the CMTC or the CT computers
not both. The CMTC is different in the fact that it is
equipped with the mini-trip feature. The CMTC, CT
consists of a electronic control module with a vacuum
fluorescent display (VFD) and function switches. The
CMTC, CT consists of a electronic module that dis-
plays compass, trip computer (CMTC only), and tem-
perature features. Actuating the STEP push button
(CMTC only) will cause the CMTC to change mode of
operation when ignition is ON. Actuating the STEP
push button (CMTC only) will cause the CMTC to
change mode of operation when ignition is ON.
Example:
²Average miles per gallon (ECO)
²Distance to empty (DTE)
²Instant miles per gallon (ECO)
²Trip odometer (ODO)
²Elapsed time (ET)
²Off
Actuating the C/T push button will cause the
CMTC, CT to change to Compass/Temperature dis-
play.
OPERATION
The Compass Mini-Trip Computer (CMTC), Com-
pass Temperature (CT) module in the overhead con-
sole has buttons used to select various functions. The
CMTC, CT selector buttons will not operate until the
ignition is in the RUN position.
When the ignition switch is first turned to the
RUN position the CMTC, CT display;
²Blanks momentarily
²All segments of the VFD will light for one sec-
ond
²Blanks momentarily
²Returns to the last mode setting selected before
the ignition was last switched OFF.
DIAGNOSIS AND TESTING - COMPASS
MINI-TRIP COMPUTER
Compass Mini-Trip Computer (CMTC) and Com-
pass Temperature (CT) data is obtained from the
Body Control Module (BCM) on the J1850 Data Bus
circuit. The CMTC and CT will display dashes (- -)
for any of the screens it did not receive the bus mes-
sages. The label corresponding to the missing infor-
mation will be lit. If no compass mini-trip computer
data is displayed, check the J1850 Data Bus circuit
communications and the BCM. If the brightness level
is improper check the J1850 Data Bus circuit.
The DRB IIItis recommended for checking the
J1850 Data Bus circuit and the BCM. Perform the
CMTC, CT self diagnosis before replacing the CMTC
or CT module.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove overhead console. Refer to Overhead
Console Removal and Installation in this section(Re-
fer to 8 - ELECTRICAL/OVERHEAD CONSOLE -
REMOVAL).
(3) Remove the screws holding Compass Mini-Trip
Computer module in the overhead console.
(4) Remove CMTC module from console assembly.
INSTALLATION
(1) Position the compass mini-trip computer mod-
ule in the overhead console.
(2) Install the ten screws holding the compass
mini-trip computer module in the overhead console.
(3) Install the overhead console. Refer to Overhead
Console Removal and Installation in this section.
(4) Connect the battery negative cable.
NOTE: If a new module has been installed, the com-
pass will have to be calibrated and the variance set.
Refer to Compass Variation Adjustment and Com-
pass Calibration in the Service Procedures section
of this group for the procedures.
UNIVERSAL TRANSMITTER
DESCRIPTION
On some RS models a Universal Transmitter trans-
ceiver is standard factory-installed equipment. The
universal transmitter transceiver is integral to the
Electronic Vehicle Information Center (EVIC) and the
Compass Mini-Trip Computer (CMTC), which is
located in the overhead console. The only visible com-
ponent of the universal transmitter are the three
transmitter push buttons centered between the mod-
RSMESSAGE SYSTEMS8M-9
ELECTRONIC VEHICLE INFO CENTER (Continued)
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ules push buttons located just rearward of the dis-
play screen in the overhead console. The three
universal transmitter push buttons are identified
with one, two or three light indicators so that they be
easily identified by sight or by feel.
Each of the three universal transmitter push but-
tons controls an independent radio transmitter chan-
nel. Each of these three channels can be trained to
transmit a different radio frequency signal for the
remote operation of garage door openers, motorized
gate openers, home or office lighting, security sys-
tems or just about any other device that can be
equipped with a radio receiver in the 286 to 399
MegaHertz (MHz) frequency range for remote opera-
tion. The universal transmitter is capable of operat-
ing systems using either rolling code or non-rolling
code technology.
The electronics module displays messages and a
small house-shaped icon with one, two or three dots
corresponding to the three transmitter buttons to
indicate the status of the universal transmitter. The
EVIC messages are:
²Cleared Channels- Indicates that all of the
transmitter codes stored in the universal transmitter
have been successfully cleared.
²Training- Indicates that the universal trans-
mitter is in its transmitter learning mode.
²Trained- Indicates that the universal transmit-
ter has successfully acquired a new transmitter code.
²Transmit- Indicates that a trained universal
transmitter button has been depressed and that the
universal transmitter is transmitting.
The universal transmitter cannot be repaired, and
is available for service only as a unit with the EVIC
or CMTC modules. If any of these components is
faulty or damaged, the complete EVIC or CMTC
module must be replaced.
OPERATION
The universal transmitter operates on a non-
switched source of battery current so the unit will
remain functional, regardless of the ignition switch
position. For more information on the features, pro-
gramming procedures and operation of the universal
transmitter, see the owner's manual in the vehicle
glove box.
DIAGNOSIS AND TESTING - UNIVERSAL
TRANSMITTER
If the universal transmitter is inoperative, but the
Electronic Vehicle Information Center (EVIC) or
Compass Mini-Trip Computer is operating normally,
see the owner's manual in the vehicle glove box for
instructions on training the universal transmitter.
Retrain the universal transmitter with a known good
transmitter as instructed in the owner's manual andtest the universal transmitter operation again. If the
unit is still inoperative, replace the faulty universal
transmitter and EVIC/CMTC module as a unit. If
both the universal transmitter and the EVIC/CMTC
module are inoperative, refer toOverhead Console
Diagnosis and Testingearlier in this group for fur-
ther diagnosis. For complete circuit diagrams, refer
toOverhead Consolein Wiring Diagrams.
AMBIENT TEMP SENSOR
DESCRIPTION
Ambient air temperature is monitored by the over-
head console through ambient temperature messages
received from the Front Control Module (FCM) over
the Programmable Communications Interface (PCI)
J1850 data bus circuit. The FCM receives a hard
wired input from the ambient temperature sensor.
The ambient temperature sensor is a variable resis-
tor mounted to a bracket that is secured with a screw
to the right side of the headlamp mounting module
grille opening, behind the radiator grille and in front
of the engine compartment.
Refer toFront Control Modulein Electronic
Control Modules. For complete circuit diagrams, refer
to the appropriate wiring information. The ambient
temperature sensor cannot be adjusted or repaired
and, if faulty or damaged, it must be replaced.
OPERATION
The ambient temperature sensor is a variable
resistor that operates on a five-volt reference signal
sent to it by the Front Control Module. The resis-
tance in the sensor changes as temperature changes,
changing the temperature sensor signal circuit volt-
age to the Front Control Module. Based upon the
resistance in the sensor, the Front Control Module
senses a specific voltage on the temperature sensor
signal circuit, which it is programmed to correspond
to a specific temperature. The Front Control Module
then sends the proper ambient temperature mes-
sages to the EVIC, CMTC over the PCI J1850 data
bus.
The thermometer function is supported by the
ambient temperature sensor, a wiring circuit, the
Front Control Module, the Programmable Communi-
cations Interface (PCI) data bus, and a portion of the
Electronics module. If any portion of the ambient
temperature sensor circuit fails, the Front Control
Module will self-diagnose the circuit.
The ambient temperature sensor circuit can also be
diagnosed by referring toDiagnosis and Testing -
Ambient Temperature Sensor, and Diagnosis
and Testing - Ambient Temperature Sensor Cir-
cuit. If the temperature sensor and circuit are con-
8M - 10 MESSAGE SYSTEMSRS
UNIVERSAL TRANSMITTER (Continued)
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The power liftgate control module communicates
on the J1850 Programmable Communication Inter-
face (PCI) Bus Circuit. Therefore, the power liftgate
control module can generate and store its own Diag-
nostic Trouble Codes (DTC). The vehicles Body Con-
trol Module (BCM) receives and supplies messages tothe power liftgate control module via the PCI bus cir-
cuit. A diagnostic scan tool, such as the DRB IIItis
used to read and troubleshoot these Diagnostic Trou-
ble Codes (DTC). Refer to the Body Diagnostic Man-
ual for a complete list of diagnostic routines.
For additional information refer to Power Liftgate
Operation. For a complete system wiring schematic
refer to Wiring Diagrams. For system operation
instructions refer to the vehicles owner manual.
Refer to the Body section of the service manual
for additional information on liftgate components
such as the prop rods, hinges, door alignment and
striker alignment.
WARNING: BE CERTAIN TO READ ALL WARNINGS
AND CAUTIONS (NOTED BELOW) IN POWER LIFT-
GATE SYSTEM OPERATION BEFORE ATTEMPTING
ANY SERVICE OF THE POWER LIFTGATE SYSTEM
OR COMPONENTS.
OPERATION
With the push of a power liftgate open/close com-
mand switch (key fob or overhead console mounted) a
signal is sent out on the J1850 PCI Data Bus circuit.
This signal is detected at the body control module
(BCM). The BCM then sends a signal out on the
J1850 PCI Data Bus circuit to the power liftgate
module. The power liftgate module then signals the
power liftgate motor to start an open or close cycle,
depending on what position the liftgate is in open or
closed.
During a liftgate open or close cycle, if the power
liftgate module detects sufficient resistance to liftgate
travel, such as an obstruction in the liftgates path,
the power liftgate control module will immediately
stop the liftgate movement and reverse travel to the
full open or closed position. The ability for the power
liftgate module to detect resistance to liftgate travel
is accomplished by hall effect sensors, drive motor
speed and pinch sensors (tape switches).
The power liftgate control module has the ability to
learn. Anytime the liftgate is opened or closed using
the power liftgate system the module learns from its
cycle. If a replacement power liftgate component is
installed or a liftgate adjustment is made, the mod-
ule will relearn the effort and/or time required to
open or close the door. This learn cycle can be per-
formed with a Diagnostic Scan Tool, such as the DRB
IIItor with a complete cycle of the liftgate, using
any one of the command switches. Refer to Standard
Procedures in this section for detailed instructions.Fig. 2 KEY FOB
1 - Left Sliding Door Switch
2 - Right Sliding Door Switch
3 - Liftgate Switch
Fig. 3 LIFTGATE FUSE LOCATION
RSPOWER LIFTGATE SYSTEM8N-3
POWER LIFTGATE SYSTEM (Continued)
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