service reset JEEP GRAND CHEROKEE 2002 WJ / 2.G User Guide

for door and liftgate open indications and to show if a
turn signal has been left on. The EVIC messages and
displays are coordinated with warning indicators in
the instrument cluster to avoid duplication.
The EVIC module contains a central processing
unit and interfaces with other electronic modules in
the vehicle over the Programmable Communications
Interface (PCI) data bus network. The PCI data bus
network 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 module includes the following display
options:
²Compass and Temperature- provides the out-
side temperature and one of eight compass readings
to indicate the direction the vehicle is facing.
²Average fuel economy- shows the average
fuel economy since the last trip computer reset.
²Distance to empty- shows the estimated dis-
tance that can be travelled with the fuel remaining
in the fuel tank. This estimated distance is computed
using the average miles-per-gallon from the last 30
gallons of fuel used.
²Instant fuel economy- shows the present fuel
economy based upon the current vehicle distance and
fuel used information.
²Trip distance- shows the distance travelled
since the last trip computer reset.
²Elapsed time- shows the accumulated igni-
tion-on time since the last trip computer reset.
²Distance to service- shows the distance
remaining until the next scheduled service interval.
²Tire Pressure- shows the tire pressure in each
tire.
²Blank screen- the EVIC compass/temperature/
trip computer VFD is turned off.
The EVIC is capable of displaying the following
alert messages, which are accompanied by an audible
announcement consisting of a series of beeps:
²TURN SIGNALS ON (with vehicle graphic)-
Indicates that a turn signal has remained on for
about 1.6 kilometers (one mile).
²PERFORM SERVICE- Indicates that a cus-
tomer programmable service interval distance has
been reached.
²DOOR OPEN (one or more, with vehicle
graphic)- Indicates that a door is open or not fully
closed.
²LIFTGATE OPEN (with vehicle graphic)-
Indicates that the liftgate is open or not fully closed.
²LIFTGLASS OPEN (with vehicle graphic)-
Indicates that the liftglass is open or not fully closed.²COOLANT LEVEL LOW (with vehicle
graphic)- Indicates that the coolant level in the
engine coolant reservoir is low.
²XX LOW PRESSURE (with vehicle graphic)
- Indicates that the air pressure in the selected tire
is low.
²WASHER FLUID LOW (with vehicle
graphic)- Indicates that the fluid level in the
washer fluid reservoir is low.
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 mem-
ory system, the EVIC will display the following mem-
ory system messages:
²MEMORY #X POSITION SET (X = Driver 1
or Driver 2)- This message appears in the EVIC
display each time the memory system is successfully
programmed. It is accompanied by an audible
announcement chime tone.
²MEMORY SYSTEM DISABLED- The memory
system is automatically disabled while the driver
side seat belt is fastened and/or while the automatic
transmission gear selector is in any position except
Park or Neutral. This message appears in the EVIC
display as a reminder when a memory switch push
button is depressed while the memory system is dis-
abled. If the REMOTE LINKED TO MEMORY cus-
tomer programmable feature has been selected, this
message will also appear when the Unlock button of
the Remote Keyless Entry (RKE) transmitter is
depressed while the memory system is disabled.
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 is being trained, which of the
three transmitter buttons is transmitting, and when
the transceiver is cleared.
If the vehicle is equipped with the optionalTire
Pressure Monitoring System, the EVIC will also
display messages and an icon indicating when the
tire air pressure falls below a given set-point, and
which of the five tires is transmitting the low pres-
sure warning, and when the condition is cleared.
Refer to the Tires/Wheels section of this manual for
complete Tire Pressure Monitoring System descrip-
tion. Refer to this section of the service manual for
EVIC modules function description for the Tire Pres-
sure Monitoring.
Data input for all EVIC functions, including VFD
dimming level, is received through PCI data bus
WJMESSAGE SYSTEMS 8M - 7
ELECTRONIC VEHICLE INFO CENTER (Continued)

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/temperature display is the normal
EVIC display. With the ignition switch in the On
position, momentarily depressing and releasing the
C/T (compass/temperature) push button switch will
cause the EVIC to return to the compass/tempera-
ture/trip computer display mode from any other
mode. While in the compass/temperature/trip com-
puter display 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
If the problem with the Electronic Vehicle Informa-
tion Center (EVIC) is a temperature reading of 130É
F or -40ÉF shown in the compass/temperature dis-
play, refer toAmbient Temperature Sensor Diag-
nosis and Testingin this group. If the problem with
the EVIC is an inaccurate or scrambled display, refer
toSelf-Diagnostic Testin this group. If the prob-lem with the EVIC is incorrect Vacuum Fluorescent
Display (VFD) dimming levels, use a DRBtscan tool
and the proper Diagnostic Procedures manual to test
for the correct dimming message inputs being
received from the Body Control Module (BCM) over
the Programmable Communications Interface (PCI)
data bus. If the problem is a no-display condition,
use the following procedures. For complete circuit
diagrams, refer toOverhead Consolein Wiring
Diagrams.
(1) Check the fused B(+) fuse in the junction block.
If OK, go to Step 2. If not OK, repair the shorted cir-
cuit or component as required and replace the faulty
fuse.
(2) Check for battery voltage at the fused B(+) fuse
in the junction block. If OK, go to Step 3. If not OK,
repair the open fused B(+) circuit to the fused B(+)
fuse in the PDC as required.
(3) Check the fused ignition switch output (run/
start) fuse in the junction block. 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 junction block. 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 EVIC 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 EVIC module. If
OK, go to Step 7. If not OK, repair the open fused
B(+) circuit to the fused B(+) fuse in the junction
block 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 EVIC module. If OK, refer to
Self-Diagnostic Testbelow for further diagnosis of
the EVIC module and the PCI data bus. If not OK,
repair the open fused ignition switch output (run/
start) circuit to the fuse in the junction block as
required.
SELF-DIAGNOSTIC TEST
A self-diagnostic test is used to determine that the
EVIC module is operating properly, and that all PCI
WJMESSAGE SYSTEMS 8M - 9
ELECTRONIC VEHICLE INFO CENTER (Continued)

data bus messages are being received for initial oper-
ation. Initiate the self-diagnostic test as follows:
(1) With the ignition switch in the Off position,
simultaneously depress and hold the C/T button and
the Reset button.
(2) Turn the ignition switch to the On position.
(3) Continue to hold both buttons depressed until
the EVIC software version information is displayed,
then release both buttons.
(4) Following completion of these tests, the EVIC
module will display one of the following messages:
a.Pass Self Test- Momentarily depress and
release the Reset button to return to the compass/
temperature/trip computer display mode. The EVIC
module is working properly.
b.Failed Self Test- The EVIC module has an
internal failure. The EVIC module is faulty and must
be replaced.
c.Not Receiving J1850 Message- The EVIC
module is not receiving proper message input
through the PCI data bus. 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 scan
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 Stan-
dard Procedures section of this group.
NOTE: If the compass reading displays a blank, 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 Standard Procedures section
of this group.
STANDARD PROCEDURE - TIRE PRESSURE
SYSTEM TEST
The following test can be used to verify two func-
tions. One, that the tire pressure sensors are trans-
mitting properly and two, the EVIC module is
receiving these transmissions accordingly.
(1) Retrain the tire sensors (Refer to 22 - TIRES/
WHEELS/TIRE PRESSURE MONITORING/SEN-
SOR - STANDARD PROCEDURE). The tire sensors
must be retrained in order to set the proper trans-
mitting time cycle (twice a minute), failure to retrain
the sensors will cause a much slower transmitting
time cycle (once a hour).(2) Using the STEP button on the overhead con-
sole, scroll to the blank display, then press the
RESET button for five seconds, a beep will sound
indicating the start of this test. The vehicle icon and
transmission counters will now be displayed, (same
display as individual tire pressure except counters
replace tire pressure values).
(3) Upon entering the test mode, the EVIC will
clear the sensor counter and each time a sensor sig-
nal for a road tire is received, the EVIC will update
the counter value (vehicle must be driven at 25 mph
to transmit). The counter values should all read the
same value. If any of the road tires indicate a differ-
ent value than another tire sensor, this is a sign of a
problem. Replace the appropriate tire sensor and
retest the system. This test will continue until any of
the overhead console buttons are pressed or the igni-
tion is turned off.
NOTE: Pressing the RESET button during the test
will sound a beep and reset all the counter values
back to zero.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the overhead console from the head-
liner (Refer to 8 - ELECTRICAL/OVERHEAD CON-
SOLE - REMOVAL).
(3) Remove the four screws that secure the Elec-
tronic Vehicle Information Center (EVIC) module to
the overhead console housing (Fig. 5).
(4) Remove the EVIC module from the overhead
console housing.
INSTALLATION
(1) Position the EVIC module onto the overhead
console housing.
(2) Install and tighten the four screws that secure
the EVIC module to the overhead console housing.
Tighten the screws to 0.9 N´m (8 in. lbs.).
(3) Install the overhead console onto the headliner
(Refer to 8 - ELECTRICAL/OVERHEAD CONSOLE -
INSTALLATION).
(4) Reconnect the battery negative cable.
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
Compass Calibration in the Service Procedures sec-
tion of this group for the procedures.
8M - 10 MESSAGE SYSTEMSWJ
ELECTRONIC VEHICLE INFO CENTER (Continued)

INSTALLATION
(1) Position the power window switch to the rear
door trim panel switch receptacle.
(2) Press firmly and evenly on the back of the
power window switch until it snaps into rear door
trim panel switch receptacle.
(3) Install the trim panel onto the rear door. (Refer
to 23 - BODY/DOORS - REAR/TRIM PANEL -
INSTALLATION) for the procedures.
(4) Reconnect the battery negative cable.
WINDOW MOTOR
DESCRIPTION
Power operated front and rear door windows are
standard equipment on this model. Each door has a
permanent magnet reversible electric motor with an
integral right angle gearbox mechanism that oper-
ates the window regulator. In addition, each power
window motor is equipped with an integral self-reset-
ting circuit breaker to protect the motor from over-
loads.
The power window motor gearbox housing is
secured to the window regulator drum housing with
screws. The window regulators used in all four doors
are single vertical post cable-and-drum type. A
molded plastic slider guided by the post is driven by
the regulator cables. The slider raises and lowers the
window glass through a steel lift plate attachment.
Front and rear glass channels within each door guide
and stabilize each end of the glass.
The power window motor and gearbox assembly
cannot be repaired and, if faulty or damaged, the
entire power window motor and gearbox unit must be
replaced. The window regulators are available for
service. (Refer to 23 - BODY/DOOR - FRONT/WIN-
DOW REGULATOR - REMOVAL) or (Refer to 23 -
BODY/DOORS - REAR/WINDOW REGULATOR -
REMOVAL) for the regulator service procedures.
OPERATION
A positive and negative battery connection to the
two motor terminals will cause the power window
motor to rotate in one direction. Reversing the cur-
rent through these same two connections will cause
the motor to rotate in the opposite direction.
When the power window motor operates, it rotates
the regulator cable drum through its gearbox. The
window regulator cable drum is connected through
two cables to the plastic slider on the vertical post.
As the cable drum rotates, it lets cable out on one
side of the drum, and takes cable in on the other side
of the drum. The changes in cable length move the
slider up or down the vertical post, raising or lower-
ing the window glass.If the window regulator or window glass bind,
encounter obstructions, or reach their travel limits it
overloads the power window motor. The overloading
condition causes the power window motor self-reset-
ting circuit breaker to open, which stops the motor
from running.
DIAGNOSIS AND TESTING - WINDOW MOTOR
Before you proceed with this diagnosis, confirm
proper switch operation. (Refer to 8 - ELECTRICAL/
ELECTRONIC CONTROL MODULES/DRIVER
DOOR MODULE - OPERATION) or (Refer to 8 -
ELECTRICAL/POWER WINDOWS/POWER WIN-
DOW SWITCH - OPERATION). For complete circuit
diagrams, refer to the appropriate wiring informa-
tion. The wiring information includes wiring dia-
grams, proper wire and connector repair procedures,
details of wire harness routing and retention, connec-
tor pin-out information and location views for the
various wire harness connectors, splices and grounds.
(1) Remove the trim panel from the door with the
inoperative power window. (Refer to 23 - BODY/
DOOR - FRONT/TRIM PANEL - REMOVAL) or
(Refer to 23 - BODY/DOORS - REAR/TRIM PANEL -
REMOVAL) for the procedures.
(2) Disconnect the door wire harness connector
from the power window motor wire harness connec-
tor. Apply battery current to one cavity of the power
window motor wire harness connector, and apply
ground to the other cavity of the connector. The
power window motor should operate in one direction.
Remember, if the window is in the full up or full
down position, the motor will not operate in that
direction by design. If OK, go to Step 3. If not OK,
replace the faulty power window motor.
(3) Reverse the battery and ground connections to
the two cavities of the power window motor wire har-
ness connector. The power window motor should now
operate in the other direction. Remember, if the win-
dow is in the full up or full down position, the motor
will not operate in that direction by design. If OK, go
to Step 4. If not OK, replace the faulty power window
motor.
(4) If the power window motor operates in both
directions, check the operation of the window glass
and regulator mechanism through its complete up
and down travel. There should be no binding or stick-
ing of the window glass or regulator mechanism
through the entire travel range. If not OK, (Refer to
23 - BODY/DOOR - FRONT/WINDOW REGULATOR
- REMOVAL) or (Refer to 23 - BODY/DOORS -
REAR/WINDOW REGULATOR - REMOVAL) to
check for proper installation or damage of the win-
dow glass mounting and operating hardware.
8N - 38 POWER WINDOWSWJ
POWER WINDOW SWITCH (Continued)

(3) Insert the hook formation on the tip of the
wiper arm through the opening in the wiper blade
superstructure ahead of the wiper blade pivot block/
latch unit far enough to engage the pivot block with
the hook (Fig. 10).
(4) Slide the wiper blade pivot block/latch up into
the hook formation on the tip of the wiper arm until
the latch release tab snaps into its locked position.
Latch engagement will be accompanied by an audible
click.
(5) Gently lower the wiper blade onto the glass.
FRONT WIPER MODULE
DESCRIPTION
The front wiper module is secured with four screws
through rubber isolators to the cowl plenum panel
beneath the cowl plenum cover/grille panel (Fig. 11).
The ends of the wiper pivot shafts that protrude
through dedicated openings in the cowl plenum cov-
er/grille panel to drive the wiper arms and blades are
the only visible components of the front wiper mod-
ule. The front wiper module consists of the following
major components:
²Bracket- The front wiper module bracket con-
sists of a long tubular steel main member that has a
stamped pivot bracket formation near each end
where the two wiper pivots are secured. A stamped
steel mounting plate for the wiper motor is secured
with welds near the center of the main member.
²Crank Arm- The front wiper motor crank arm
is a stamped steel unit with a slotted hole on the
driven end that is secured to the wiper motor outputshaft with a nut, and a ball stud secured to the drive
end.
²Linkage- Two stamped steel drive links con-
nect the wiper motor crank arm to the pivot lever
arms. The passenger side drive link has a plastic
socket-type bushing on each end. The driver side
drive link has a plastic socket-type bushing on one
end, and a plastic sleeve-type bushing on the other
end. The socket-type bushing on one end of each
drive link is snap-fit over the ball stud on the lever
arm of its respective pivot. The driver side drive link
sleeve-type bushing end is then fit over the motor
crank arm ball stud, and the other socket-type bush-
ing of the passenger side drive link is snap-fit over
the exposed end of the wiper motor crank arm ball
stud.
²Motor- The front wiper motor is secured with
three screws to the motor mounting plate near the
center of the wiper module bracket. The wiper motor
output shaft passes through a hole in the module
bracket, where a nut secures the wiper motor crank
arm to the motor output shaft. The two-speed perma-
nent magnet wiper motor features an integral trans-
mission, an internal park switch, and an internal
automatic resetting circuit breaker.
²Pivots- The two front wiper pivots are secured
to the ends of the wiper module bracket. The crank
arms that extend from the bottom of the pivot shafts
each have a ball stud on their end. The upper end of
each pivot shaft where the wiper arms will be fas-
tened each has an externally serrated drum with a
threaded stud secured to it.
The front wiper module cannot be adjusted or
repaired. If any component of the module is faulty or
damaged, the entire front wiper module unit must be
replaced. The reinforcement bracket and stud plate
are available for service replacement.OPERATION
The front wiper module operation is controlled by
the battery current inputs received by the wiper
motor from the wiper on/off and wiper high/low
relays. The wiper motor speed is controlled by cur-
rent flow to either the low speed or the high speed
set of brushes. The park switch is a single pole, sin-
gle throw, momentary switch within the wiper motor
that is mechanically actuated by the wiper motor
transmission components. The park switch alter-
nately closes the wiper park switch sense circuit to
ground or to battery current, depending upon the
position of the wipers on the glass. This feature
allows the motor to complete its current wipe cycle
after the wiper system has been turned Off, and to
park the wiper blades in the lowest portion of the
wipe pattern. The automatic resetting circuit breaker
protects the motor from overloads. The wiper motor
Fig. 11 Front Wiper Module
1 - FRONT WIPER MODULE
2 - SCREW (4)
3 - WIRE HARNESS CONNECTOR
4 - LOWER COWL PLENUM PANEL
8R - 16 FRONT WIPERS/WASHERSWJ
FRONT WIPER BLADE (Continued)

JUNCTION BLOCK
DESCRIPTION
An electrical Junction Block (JB) is concealed
beneath the driver side of the instrument panel in
the passenger compartment of the vehicle (Fig. 3).
The JB combines the functions previously provided
by a separate fuseblock module and relay center. The
JB serves to simplify and centralize numerous elec-
trical components, as well as to distribute electrical
current to many of the accessory systems in the vehi-
cle. It also eliminates the need for numerous splice
connections. The JB houses up to thirty-three blade-
type mini fuses, up to two blade-type automatic
resetting circuit breakers, the electronic combination
flasher, the Daytime Running Lamp (DRL) module
(Canada only) and up to twelve International Stan-
dards Organization (ISO) relays (three standard-type
and nine micro-type). The JB also incorporates an
integral connector and mounting for the Body Con-
trol Module (BCM). The BCM is secured with four
screws directly to the dash panel side of the JB.
Refer toBody Control Modulein Electronic Con-
trol Modules for additional information covering the
BCM.
The molded plastic JB housing has integral mounts
that are secured with two screws and two snap
retainers to the instrument panel steering column
support bracket behind the instrument panel steer-ing column opening cover. The JB is concealed above
the molded plastic instrument panel fuse cover. Inte-
gral latches molded into the fuse cover secure it the
JB, the BCM and the 16-way data link connector tab
of the instrument panel steering column support
bracket. The fuse cover can be pulled downward to
disengage the latches and provide service access to
all of the fuses, relays and wire harness connectors of
the JB. The fuse cover has a fuse puller and spare
fuses secured to its upper surface. Refer toInstru-
ment Panel Fuse Coverin Body for additional ser-
vice information.
The JB unit cannot be repaired and is only ser-
viced as an assembly. If any internal circuit or the JB
housing is faulty or damaged, the entire JB unit
must be replaced. The BCM is available for separate
service replacement.
OPERATION
All of the circuits entering and leaving the Junc-
tion Block (JB) do so through up to five wire harness
connectors, which are connected to the JB through
integral connector receptacles molded into the JB
housing. Internal connection of all of the JB circuits
is accomplished by a printed circuit board. There are
also two separate wire harness connections to con-
nector receptacles that are integral to the BCM.
Refer toJunction Blockin Wiring Diagrams for
additional information and the location of complete
JB circuit diagrams.
REMOVAL
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. DISCON-
NECT AND ISOLATE THE BATTERY NEGATIVE
(GROUND) CABLE, THEN WAIT TWO MINUTES FOR
THE AIRBAG SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE AIRBAG SYSTEM. FAILURE TO TAKE
THE PROPER PRECAUTIONS COULD RESULT IN
ACCIDENTAL AIRBAG DEPLOYMENT AND POSSI-
BLE PERSONAL INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the fuse cover from the bottom of the
Junction Block (JB).
(3) Remove the steering column opening cover
from the instrument panel. Refer toSteering Col-
umn Opening Coverin Body for the location of
steering column opening cover removal procedures.
Fig. 3 Junction Block Location
1 - REAR LATCHES
2 - JUNCTION BLOCK AND BODY CONTROL MODULE UNIT
3 - INSTRUMENT PANEL FUSE COVER
4 - SIDE LATCH
5 - FRONT LATCHES
WJ8W-97 POWER DISTRIBUTION 8W - 97 - 5

Both the manual A/C Heater control panel and the
AZC control panel are serviced only as complete
units and cannot be repaired. If faulty or damaged,
the entire control panel unit must be replaced.
DIAGNOSIS AND TESTING - AUTOMATIC ZONE
CONTROL SYSTEM
The Automatic Zone Control (AZC) control module
has a system self-diagnostic mode which continuously
monitors various parameters during normal system
operation. If a system fault is detected, a current and
historical fault is recorded. When the current fault is
cleared, the historical fault remains until reset (man-
ually or automatically). Both the current and histor-
ical fault codes can be accessed through either the
front panel, or over the Programmable Communica-
tions Interface (PCI) bus using a DRBIIItscan tool,
and the appropriate diagnostic information.
The AZC control module is capable of three differ-
ent types of self-diagnostic tests, as follows:
²Fault Code Tests
²Input Circuit Tests
²Output Circuit/Actuator Tests
The information that follows describes:
²How to read the self-diagnostic display
²How to enter the AZC control module self-diag-
nostic test mode
²How to select the self-diagnostic test types
²How to perform the different tests
ENTERING THE AZC SELF-DIAGNOSTIC MODE
To enter the AZC self-diagnostic mode, perform the
following:
(1) Depress the a/c and recirc buttons at the same
time and hold. Rotate the left temperature control
knob clockwise (CW) one detent.
(2) If you continue to keep the a/c and recirc but-
tons depressed, the AZC control module will perform
a Segment Test of the Vacuum Fluorescent (VF) dis-
play. In the Segment Test you should see all of the
display segments illuminate as long as both buttons
are held. If a display segment fails to illuminate, the
vacuum fluorescent display is faulty and the a/c
heater control must be replaced.
(3) After viewing the Segment Test, release the
A/C and Recirc buttons and the display will clear
momentarily.Ifa0isdisplayed, then no faults
are set in the system.Should there be any faults,
either9current9or9historical9, all fault codes will be
displayed in ascending numerical sequence (note no
effort is made to display fault codes in chronological
order). Each fault code is displayed for one second
before the next code is displayed. Once all fault codes
have been displayed, the system will then repeat the
fault code numbers. This will continue until the left
side set temperature control is moved at least onedetent position in the CW direction or the ignition is
turned9OFF9.
FAULT CODE TESTS
Fault codes are two-digit numbers that identify a
circuit that is malfunctioning. There are two differ-
ent kinds of fault codes.
1.Current Fault Codes- Current means the
fault is present right now. There are two types of cur-
rent faults: input faults, and system faults.
2.Historical Fault Codes- Historical or stored
means that the fault occurred previously, but is not
present right now. A majority of historical fault codes
are caused by intermittent wire harness or wire har-
ness connector problems.
CURRENT FAULT CODES
Input faults 01 = IR thermister circuit
open
02 = IR thermister circuit
shorted
03 = Fan pot shorted
04 = Fan pot open
05 = Mode pot shorted
06 = Mode pot open
07 = IR sensor delta too
large
08 = Reserved
09 = Reserved
10 = One of four motor
drivers has drive9A9
shorted to ground
11 = Engine air intake
temperature Buss
message missing
12 = Country code Buss
message missing
24 - 18 CONTROLSWJ
A/C HEATER CONTROL (Continued)