Electronic Control Modules CHRYSLER VOYAGER 2002 Workshop Manual

CONDITION POSSIBLE CAUSE CORRECTION
(5) FAULTY HORN SWITCH. (5) REPLACE DRIVER AIRBAG
MODULE TRIM COVER.
(6) FAULTY CLOCKSPRING. (6) REPLACE CLOCKSPRING.
(7) FAULTY FRONT
CONTROL MODULE.(7) REFER TO ELECTRONIC
CONTROL MODULES/FRONT
CONTROL MODULE.
FUSE BLOWS WHEN HORN SOUNDS (1) SHORT CIRCUIT IN
HORN OR HORN WIRING.(1) REMOVE HORN RELAY, CHECK
FOR SHORTED HORN OR HORN
WIRING. DISCONNECT HORN WIRE
HARNESS TO ISOLATE SHORT
AND REPAIR AS NECESSARY.
(2) FAULTY CLOCKSPRING. (2) REPLACE CLOCKSPRING.
FUSE BLOWS WITHOUT BLOWING
HORN(1) SHORT CIRCUIT. (1) REMOVE RELAY, INSTALL NEW
FUSE, IF FUSE DOES NOT BLOW
REPLACE HORN RELAY. IF FUSE
BLOWS WITH RELAY REMOVED,
CHECK FOR SHORT TO GROUND
WITH OHMMETER ON CIRCUIT
BETWEEN TERMINALS 30 & 86
AND THE FUSE TERMINAL. REPAIR
AS NECESSARY.
(2) FAULTY CLOCKSPRING. (2) REPLACE CLOCKSPRING.
HORN
DIAGNOSIS AND TESTING - HORN
HORN
(1) Disconnect wire connector at horn.
(2) Using a voltmeter, connect one lead to ground
terminal and the other lead to the positive wire ter-
minal (Fig. 1).
(3) Depress the horn switch, battery voltage
should be present.
(4) If no voltage, refer toHORNS WILL NOT
SOUND. If voltage is OK, go to step Step 5.
(5) Using ohmmeter, test ground wire for continu-
ity to ground.
(6) If no ground repair as necessary.
(7) If wires test OK and horn does not sound,
replace horn.
HORNS SOUND CONTINUOUSLY
CAUTION: Continuous sounding of horns may
cause relay to fail.The horn switch (membrane) sometimes can be the
cause without the switch being depressed.
(1) Remove the horn relay from the intelligent
power module.
(2) Using a continuity tester, test continuity from
the X3 cavity of the horn relay to ground. Refer to
the appropriate wiring information. The wiring infor-
mation includes wiring diagrams, proper wire and
connector repair procedures, details of wire harness
routing and retention, connector pin-out information
and location views for the various wire harness con-
nectors, splices and grounds.
(a) If continuity is detected, proceed to step Step
3.
(b) If NO continuity, replace the horn relay.
(3) Remove the airbag trim cover from the steering
wheel and disengage horn connector.
(4) Install horn relay into Integrated Power Mod-
ule (IPM).
(a) If horn does not sound, replace airbag trim
cover.
(b) If horn sounds, repair grounded X3 circuit
from IPM to clockspring in the steering column.
HORNS WILL NOT SOUND
Check horn fuse#8intheIPM. If fuse is blown,
check for a shorted switch in the airbag module. and
refer to FUSE BLOWN section. If fuse is OK, refer to
FUSE OK section.
RSHORN8H-3
HORN SYSTEM (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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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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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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POWER LIFTGATE SYSTEM
DESCRIPTION
Some vehicles are equipped with an automatic
opening and closing power liftgate system (Fig. 1).
This power liftgate system is a complex system con-
sisting of many components. Some of these compo-
nents are the liftgate gear motor assembly, latch
assembly, lift gear and rod, liftgate control module,
chime/thermistor, full open switch, engage actuator,
pinch sensor, liftgate handle switch, overhead console
switch, key fob switches (Fig. 2), pawl switch and
ratchet switch.
The power liftgate system has its own door control
module, located on the vehicles left body D-pillar
behind the trim panel. (Refer to 8 - ELECTRICAL/
ELECTRONIC CONTROL MODULES/DOOR CON-
TROL MODULE - DESCRIPTION) The power
liftgate gear motor assembly is located just above the
control module. The latch assembly is located in the
bottom center of the power liftgate, below the exte-
rior liftgate handle switch. The power liftgate full
open switch, engage actuator, lift gear and rod are
part of the liftgate gear motor assembly. The pawl
and ratchet switches are part of the latch assembly.The pinch sensor or sensors are located along the
right and left sides of the power liftgate, just above
the body line. The liftgate handle switch is an power
release switch and is located in the rear light bar
assembly, just above the license plate. The overhead
console switch is an power open and close command
switch located in the vehicles overhead console.
Safety is of the utmost concern with the power lift-
gate system. Software technology has enabled the
power liftgate control module to detect resistance to
liftgate travel, which allows the power liftgate to stop
and reverse direction anytime an obstruction is felt
or any of the command switches are operated (only in
closing direction). Battery voltage is supplied to the
power liftgate system through a 40 amp fuse, located
in the Intelligent Power Module (IPM) assembly (Fig.
3). In the unlikely event that the power liftgate sys-
tem develops a fault the power liftgate can still be
operated manually with a key, just like a standard
manual liftgate.
Fig. 1 POWER LIFTGATE INTRODUCTION
8N - 2 POWER LIFTGATE SYSTEMRS
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The power liftgate system is designed with a num-
ber of system inhibitors. These inhibitors are neces-
sary for safety and / or feasibility of the power
liftgate system. Refer to power liftgate system inhib-
itors noted below:
POWER LIFTGATE SYSTEM INHIBITORS
²The Power Liftgate may not operate in extreme
temperatures. These extreme temperatures will be
approximately -12É F (-24.4É C) on the low side and
143É F (61.6É C) for the high side. A chime/thermister
assembly in the rear light bar assembly monitors the
outside temperature.
²The vehicles transmission must be in park or
neutral for the power liftgate to start a cycle.
²If multiple obstacles are detected during the
same power open or close cycle the liftgate goes into
manual operation.
²If severe Diagnostic Trouble Codes (DTC) are
stored in the power liftgate control module.
POWER LIFTGATE SYSTEM CAUTIONS AND
WARNINGS
WARNING: ALWAYS DISCONNECT THE NEGATIVE
BATTERY CABLE BEFORE ATTEMPTING ANY
POWER LIFTGATE SYSTEM SERVICE.
WARNING: THERE IS A SMALL AREA ON BOTH
SIDES OF THE LOWER POWER LIFTGATE WHICH
ARE NOT PROTECTED BY PINCH SENSORS.
EXTREME CARE MUST BE TAKEN TO PREVENT
OBJECTS FROM ENTERING THIS AREA ONCE THE
LIFTGATE REACHES THE SECONDARY LATCH
CONTACT (APPROXIMATELY 1/2 INCH BEFORE
FULLY CLOSED).
WARNING: NEVER ATTEMPT TO ENTER OR EXIT
THE VEHICLE WITH THE LIFTGATE IN MOTION.
YOU COULD DAMAGE THE POWER LIFTGATE SYS-TEM AND/OR COMPONENTS AND/OR CAUSE PER-
SONAL INJURY.
WARNING: NEVER STICK OBJECTS IN THE POWER
LIFTGATE WHEN CINCHING CLOSED. YOU COULD
DAMAGE THE VEHICLE, POWER LIFTGATE SYS-
TEM COMPONENTS AND/OR CAUSE PERSONAL
INJURY.
DIAGNOSIS AND TESTING - POWER LIFTGATE
SYSTEM
The power opening and closing power liftgate sys-
tem is a complex system containing many compo-
nents and modules. In order to obtain conclusive
testing the Programmable Communications Interface
(J1850) data bus network and all of the electronic
modules that provide inputs to, or receive outputs
from the power liftgate system must be checked.
The power liftgate system was designed to be diag-
nosed with an appropriate diagnostic scan tool, such
as the DRB IIIt. The most reliable, efficient, and
accurate means to diagnose the power liftgate system
requires the use of a DRB IIItscan tool and the
proper Body Diagnostic Procedures manual. The
DRB IIItcan be used to observe various switch sta-
tuses throughout the power liftgate system to help
the technician diagnose a defective switch or compo-
nent. The DRB IIItcan also be used to actuate var-
ious components throughout the power liftgate
system to help the technician diagnose a defective
component.
Before any testing of the power liftgate system is
attempted, the battery should be fully charged, all
built-in power liftgate system inhibitors read and
understood (Refer to power liftgate system operation)
and all wire harness and ground connections
inspected around the affected areas on the vehicle.
Following are quick reference diagnostic tables to
help when diagnosing and testing the power liftgate
system.
8N - 4 POWER LIFTGATE SYSTEMRS
POWER LIFTGATE SYSTEM (Continued)
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The eight-way power seat is also available with the
heated seat and memory seat system that automati-
cally positions the power seat for two different driv-
ers. Refer toHeated Seatsfor more information on
the heated seat option. Refer toDescription Mem-
ory Seat Systemin this section for more informa-
tion on the memory seat system.
The power seat system includes the following com-
ponents:
²Power seat recliners
²Power seat switches
²Power seat tracks
²Circuit breaker
The power seat system with memory and heated
seat options includes the following components:
²Power seat recliner
²Power seat switch
²Power seat track.
²Memory Seat Mirror Module (MSMM)
²Memory set switch
²Heated Seat Module (HSM)
²Heated seat switch
²Electronic Vehicle Information Center (EVIC)
²Programmable Communications Interface (PCI)
data bus network
Refer to Wiring Diagrams for complete circuit dia-
grams. Following are general descriptions and opera-
tions for the major components in the power seat
system and memory seat system.
DESCRIPTION - MEMORY SYSTEM
An electronic memory system is available on some
models. The memory system is able to store and
recall the driver side power seat positions (including
the power recliner position) and both outside side
view mirrors positions for two drivers. On vehicles
equipped with a factory radio, the memory system is
also able to store and recall radio station presets for
two drivers. The memory system also will store and
recall the last station listened to for each driver, even
if it is not one of the preset stations.
The memory system will automatically return to
its preset settings when the corresponding numbered
button of the memory switch is depressed, or when
the doors are unlocked using the corresponding
Remote Keyless Entry (RKE) transmitter. A customer
programmable feature of the memory system allows
the RKE recall of memory features to be disabled, if
desired. This programmable feature is internal in the
EVIC module, which is located in the overhead con-
sole.
A Memory Seat Mirror Module (MSMM) is used on
some models to control and integrate the many elec-
tronic functions and features included in the memory
seat and mirror systems.
The memory system includes the following compo-
nents:
²Memory Seat Mirror Module (MSMM)
²Memory set switch
²Position potentiometers on both outside side
view mirrors
²Position potentiometers on the driver side power
seat track and power seat recliner motors.
²Electronic Vehicle Information Center (EVIC)
²Radio receiver (if PCI data bus capable).
Certain functions of the memory system rely upon
resources shared with other electronic modules in the
vehicle over the Programmable Communications
Interface (PCI) J1850 data bus network. The PCI
data bus network allows the sharing of sensor infor-
mation. This helps to reduce wire harness complexity,
internal controller hardware, and component sensor
current loads. At the same time, this system provides
increased reliability, enhanced diagnostics, and
allows the addition of many new feature capabilities.
Initial diagnosis of these electronic modules or the
PCI data bus network requires the use of a DRB IIIt
scan tool and the proper Diagnostic Procedures man-
ual. If this method does not prove conclusive, the use
of a automotive meter such as the Fluket, the proper
wiring schematics and the service manual diagnostic
routines are required.
The other electronic modules that may affect mem-
ory system operation are as follows:
Fig. 1 Identifying a Side Airbag Equipped Seat
1 - Airbag Label
8N - 52 POWER SEAT SYSTEMRS
POWER SEAT SYSTEM (Continued)
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²Body Control Module (BCM)- Refer toBody
Control Modulein Electronic Control Modules for
more information.
²Powertrain Control Module (PCM)- Refer to
Powertrain Control Modulein Electronic Control
Modules for more information.
Refer toHeated Seat Systemfor more informa-
tion on the heated seat system. Refer toRemote
Keyless Entry Systemin Power Lock Systems for
more information on the RKE system.
Refer toWiring Diagramsfor complete circuit
diagrams. Following are descriptions, theory of oper-
ation, diagnosis/testing procedures and removal/in-
stallation procedures of the major components in the
memory and power seat systems.
OPERATION
OPERATION - POWER SEAT SYSTEM
The power seat system receives battery current
through fuse #22 in the Intelligent Power Module
and a circuit breaker under the front seats, regard-
less of the ignition switch position.
When a power seat switch control knob or knobs
are actuated, a battery feed and a ground path are
applied through the switch contacts to the appropri-
ate power seat track adjuster motor. The selected
adjuster motor operates to move the seat track
through its drive unit in the selected direction until
the switch is released, or until the travel limit of the
seat track is reached. When the switch is moved in
the opposite direction, the battery feed and ground
path to the motor are reversed through the switch
contacts. This causes the adjuster motor to run in the
opposite direction.
No power seat switch should be held applied in any
direction after the seat track has reached its travel
limit. The power seat track each contain a self-reset-
ting circuit breaker to protect them from overload.
However, consecutive or frequent resetting of the cir-
cuit breaker must not be allowed to continue, or the
motor may be damaged. Refer to the owner's manual
in the vehicle glove box for more information on the
features, use and operation of the power seat system.
OPERATION - MEMORY SYSTEM
The memory system receives battery current
through fuse #22 in the Intelligent Power Module
and the power seat system circuit breaker, located
under each front seat near the rear edge of the seat
cushion pans. The Memory Seat Mirror Module
(MSMM) will drive a maximum of 2 motors at a time
in a given direction. If conflicting directions are
requested, the priority for response will be as follows:
²Seat Track Rearward or Forward²Seat Front Down or Up
²Seat Rear Down or Up
²Recliner Rearward or Forward
The inputs from these switches to the MSMM is a
current limited battery source fed by the MSMM.
This protects the MSMM printed circuit board traces
from acting as fuses. All of these switch contact
inputs to the MSMM are normally closed to ground,
except when actuated.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the memory system. For diagnosis of the MSMM,
the PCI data bus, or the other electronic modules on
the PCI data bus that provide inputs and outputs for
the memory system, the use of a DRBIIItscan tool
and the proper Diagnostic Procedures manual are
recommended.
ELECTRONIC VEHICLE INFORMATION CENTER
The Electronic Vehicle Information Center (EVIC)
serves as the user interface for the memory system.
It displays memory system status messages and pro-
vides the user with the means for enabling and dis-
abling the many customer programmable features
available on the vehicle, including those for the mem-
ory system.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the EVIC. Refer toElectronic Vehicle Informa-
tion Centerin Overhead Console Systems for more
information on the EVIC.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - POWER SEAT
SYSTEM
Following are tests that will help to diagnose the
hard wired components and circuits of the power seat
system. However, if the vehicle is also equipped with
the optional memory system, these tests may not
prove conclusive in the diagnosis of the driver side
power seat. In order to obtain conclusive testing of
the driver side power seat with the memory system
option, the Programmable Communications Interface
(PCI) data bus network and all of the electronic mod-
ules that provide inputs to, or receive outputs from
the memory system components must be checked.
The most reliable, efficient, and accurate means to
diagnose the driver side power seat with the memory
system option requires the use of a DRB IIItscan
tool and the proper Diagnostic Procedures manual.
The DRB IIItscan tool can provide confirmation that
the PCI data bus is functional, that all of the elec-
tronic modules are sending and receiving the proper
messages on the PCI data bus, and that the memory
RSPOWER SEAT SYSTEM8N-53
POWER SEAT SYSTEM (Continued)
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(3) Remove the screws that secure the outboard
seat cushion side shield to the seat cushion frame.
Refer to the Body section of the service manual for
the procedure.
(4) Pull the outboard seat cushion side shield away
from the seat cushion frame far enough to access the
power seat switch wire harness connector.
(5) Disconnect the power seat wire harness connec-
tor from the power seat switch connector receptacle.
(6) Remove the screws that secure the power seat
switch to the inside of the outboard seat cushion side
shield.
(7) Remove the power seat switch from the out-
board seat cushion side shield.
INSTALLATION
(1) Position the power seat switch onto the out-
board seat cushion side shield.
(2) Install and tighten the screws that secure the
power seat switch to the inside of the outboard seat
cushion side shield. Tighten the screws to 1.5 N´m
(14 in. lbs.).
(3) Reconnect the power seat wire harness connec-
tor to the power seat switch connector receptacle.
(4) Position the outboard seat cushion side shield
onto the seat cushion frame
(5) Install and tighten the screws that secure the
outboard seat cushion side shield to the seat cushion
frame. Tighten the screws to 1.5 N´m (14 in. lbs.).
(6) Install the switch knobs on the switch control
levers, if equipped.
(7) Reconnect the battery negative cable.
MEMORY SET SWITCH
DESCRIPTION
Vehicles equipped with the memory system have a
memory switch mounted to the driver side front door
trim panel (Fig. 5). This switch is used to set and
recall all of the memory system settings for up to two
drivers. The memory switch is a resistor multiplexed
unit that is hard wired to the Body Control Module
(BCM). The BCM sends out the memory system set
and recall requests to the other electronic modules
over the Programmable Communications Interface
(PCI) data bus.
The memory switch cannot be adjusted or repaired
and, if faulty or damaged, it must be replaced. For
complete circuit diagrams, refer toWiring Dia-
grams.
OPERATION
The memory switch has three momentary switch
buttons labeled Set, 1 and 2. The Driver 1 and Driver
2 buttons are back-lit with Light-Emitting Diodes
(LED) for visibility. When the memory set switch is
depressed, a resistance value is sent to the Body
Control Module via hard wired connections. When
the memory system is in ªsetº mode a chime will be
generated by the body control module.
Fig. 4 Removing Switch Control Knobs - Typical
Fig. 5 Memory Switch Location
1 - Memory Switch
2 - Switch Bezel
8N - 56 POWER SEAT SYSTEMRS
DRIVER SEAT SWITCH (Continued)
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