sensor DODGE TOWN AND COUNTRY 2001 Manual Online

INSTALLATION - 3.3/3.8L
(1) Install coil over studs on bracket.
(2) Install 2 bolts to ignition coil.
(3) Install 2 nuts to the ignition coil studs. Tighten
nuts and bolts.
(4) Connect the electrical connector to the ignition
coil.
(5) Install the ignition cables to the ignition coil.
(6) Reposition the Power steering reservoir. Slide
bracket over the mounting stud (Fig. 12).
(7) Install 2 bolts the Power steering reservoir to
intake manifold.
(8) Tighten the lower nut to stud on ignition coil
bracket.
(9) Install the throttle and speed control cables to
clip.
(10) Connect the negative battery cable.
KNOCK SENSOR
DESCRIPTION
The knock sensor threads into the cylinder block.
The knock sensor is designed to detect engine vibra-
tion that is caused by detonation.
OPERATION
When the knock sensor detects a knock in one of
the cylinders, it sends an input signal to the PCM. In
response, the PCM retards ignition timing for all cyl-
inders by a scheduled amount.Knock sensors contain a piezoelectric material
which constantly vibrates and sends an input voltage
(signal) to the PCM while the engine operates. As the
intensity of the crystal's vibration increases, the
knock sensor output voltage also increases.
The voltage signal produced by the knock sensor
increases with the amplitude of vibration. The PCM
receives as an input the knock sensor voltage signal.
If the signal rises above a predetermined level, the
PCM will store that value in memory and retard
ignition timing to reduce engine knock. If the knock
sensor voltage exceeds a preset value, the PCM
retards ignition timing for all cylinders. It is not a
selective cylinder retard.
The PCM ignores knock sensor input during engine
idle conditions. Once the engine speed exceeds a
specified value, knock retard is allowed.
Knock retard uses its own short term and long
term memory program.
Long term memory stores previous detonation
information in its battery-backed RAM. The maxi-
mum authority that long term memory has over tim-
ing retard can be calibrated.
Short term memory is allowed to retard timing up
to a preset amount under all operating conditions (as
long as rpm is above the minimum rpm) except WOT.
The PCM, using short term memory, can respond
quickly to retard timing when engine knock is
detected. Short term memory is lost any time the
ignition key is turned off.
NOTE: Over or under tightening affects knock sen-
sor performance, possibly causing improper spark
control.
REMOVAL - 2.4L
The knock sensor threads into the side of the cyl-
inder block in front of the starter (Fig. 13).
(1) Disconnect electrical connector from knock sen-
sor.
(2) Use a crow foot socket to remove the knock
sensors.
REMOVAL - 3.8L
The knock sensor threads into the side of the cyl-
inder block in the rear.
(1) Disconnect the negative battery cable.
(2) Raise vehicle and support.
(3) On All Wheel Drive vehicles remove the PTU
(Power Transfer Unit), refer to the Transmission sec-
tion for more information.
(4) Disconnect electrical connector from knock sen-
sor.
(5) Use a crow foot socket to remove the knock
sensor.
Fig. 12 IGNITION COIL BRACKET 3.3/3.8L
RSIGNITION CONTROL8I-7
IGNITION COIL (Continued)
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INSTALLATION - 2.4L
The knock sensor threads into the side of the cyl-
inder block in front of the starter (Fig. 13).
(1) Install knock sensor. Tighten knock sensor to
10 N´m (7 ft. lbs.) torque.Over or under tighten-
ing effects knock sensor performance, possibly
causing improper spark control.
(2) Attach electrical connector to knock sensor.
INSTALLATION - 3.8L
The knock sensor threads into the side of the cyl-
inder block in the rear.
(1) Install knock sensor. Tighten knock sensor to
10 N´m (7 ft. lbs.) torque.Over or under tighten-
ing effects knock sensor performance, possibly
causing improper spark control.
(2) Attach electrical connector to knock sensor.
(3) On All Wheel Drive vehicles install the PTU
(Power Transfer Unit) for the rear wheels, refer to
the Transmission section for more information.
(4) Lower vehicle.
(5) Connect the negative cable.
SPARK PLUG
DESCRIPTION - STANDARD 2.4L
All engines use resistor spark plugs. They have
resistance values ranging from 6,000 to 20,000 ohms
when checked with at least a 1000 volt spark plug
tester.
Do not use an ohm meter to check the resis-
tance of the spark plugs. This will give an inac-
curate reading.
Refer to the Specifications section for gap and type
of spark plug.
DESCRIPTION - PLATINUM 3.3/3.8L
These engines utilize platinum spark plugs. Refer
to the maintenance schedule.
All engines use resistor spark plugs. They have
resistance values ranging from 6,000 to 20,000 ohms
when checked with at least a 1000 volt spark plug
tester.
Do not use an ohm meter to check the resis-
tance of the spark plugs. This will give an inac-
curate reading.
The spark plugs are double platinum and have a
recommended service life of 100,000 miles for normal
driving conditions per schedule A in this manual. The
spark plugs have a recommended service life of
75,000 miles for severe driving conditions per sched-
ule B in this manual. A thin platinum pad is welded
to both electrode ends as show in (Fig. 14). Extreme
care must be used to prevent spark plug cross
threading, mis-gaping and ceramic insulator damage
during plug removal and installation.
Fig. 13 Knock Sensor
1 - GENERATOR
2 - INTAKE MANIFOLD
3 - KNOCK SENSOR
4-STARTER
Fig. 14 Platinum Pads
1 - APPLY ANTI-SEIZE COMPOUND HERE ONLY
2 - PLATINUM SPARK SURFACE
8I - 8 IGNITION CONTROLRS
KNOCK SENSOR (Continued)
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SPEEDOMETER DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
NO POINTER
MOVEMENT1. INTERNAL CLUSTER
FAILURE.1.A. PERFORM CLUSTER SELF-DIAGNOSTIC TEST
AND CHECK FOR FAULT CODES.
²IF SPEEDOMETER POINTER MOVES TO
CALIBRATION POINTS DURING TEST LOOK FOR
ANOTHER POSSIBLE CAUSE OF FAILURE.
²IF THE POINTER DOESN'T MOVE DURING TEST,
CHECK FOR POWER AND GROUND TO THE MIC.
IF POWER AND GROUND ARE PRESENT GO TO
STEP 1.B.
1.B. REPLACE CLUSTER. GO TO STEP 1.C.
1.C. CONNECT CLUSTER INTO INSTRUMENT
PANEL WIRING HARNESS. PLACE IT BACK INTO
THE PROPER POSITION IN THE INSTRUMENT
PANEL. PUT IN THE TOP FOUR MOUNTING
SCREWS AND SECURE THE CLUSTER TO THE
INSTRUMENT PANEL.
2. NO SPEED PCI BUS
MESSAGE OR ZERO
MPH PCI SPEED BUS
MESSAGE.2.A. CHECK THE PCM (CODE 10) USING A DRB IIIT
SCAN TOOL. IF OK, GO TO STEP 2.B. IF NOT OK,
REFER TO THE PROPER ENGINE DIAGNOSTIC
PROCEDURES MANUAL TO REPAIR THE PCM.
2.B. CHECK THE SPEED SIGNAL INPUT INTO THE
PCM. THE SPEED SIGNAL ORIGINATES FROM ONE
OF THE FOLLOWING SOURCES:
²A DISTANCE SENSOR FOR VEHICLES WITH 3
SPEED AUTOMATIC TRANSMISSION. CHECK
CONTINUITY FROM DISTANCE SENSOR TO PCM.
IF OK, REPLACE DISTANCE SENSOR. IF NOT OK,
REPAIR WIRING.
²THE TCM FOR VEHICLES WITH THE 4 SPEED
ELECTRONIC TRANSMISSIONS. CHECK
CONTINUITY FROM TCM TO PCM. IF OK, USE A
DRB IIITSCAN TOOL TO CHECK TCM. REFER TO
THE PROPER TRANSMISSION DIAGNOSTIC
PROCEDURES MANUAL TO REPAIR THE TCM. IF
NOT OK, REPAIR WIRING.
8J - 4 INSTRUMENT CLUSTERRS
INSTRUMENT CLUSTER (Continued)
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CONDITION POSSIBLE CAUSES CORRECTION
ERRATIC POINTER
MOVEMENT1. ERRATIC MESSAGE
FROM ANOTHER
MODULE.1.A. CHECK THE BCM USING A DRB IIITSCAN
TOOL IF OK, GO TO STEP 1.B. IF NOT OK, REFER
TO THE PROPER BODY DIAGNOSTIC
PROCEDURES MANUAL TO REPAIR THE BCM.
1.B. CHECK THE PCM USING A DRB IIITSCAN
TOOL. IF OK, GO TO STEP 1.C. IF NOT OK, REFER
TO THE ENGINE DIAGNOSTIC PROCEDURES
MANUAL TO REPAIR THE PCM.
1.C. CHECK THE SPEED SIGNAL INPUT INTO THE
PCM. THE SPEED SIGNAL ORIGINATES FROM ONE
OF THE FOLLOWING SOURCES:
²A DISTANCE SENSOR FOR VEHICLES WITH 3
SPEED AUTOMATIC TRANSMISSION. CHECK
CONTINUITY FROM DISTANCE SENSOR TO PCM.
IF OK, REPLACE DISTANCE SENSOR. IF NOT OK,
REPAIR WIRING.
²THE TCM FOR VEHICLES WITH THE 4 SPEED
ELECTRONIC TRANSMISSIONS. CHECK
CONTINUITY FROM TCM TO ENGINE
CONTROLLER. IF OK, USE A DRB IIITSCAN TOOL
TO CHECK TCM. REFER TO THE PROPER
TRANSMISSION DIAGNOSTIC PROCEDURES
MANUAL TO REPAIR THE TCM. IF NOT OK, REPAIR
WIRING.
2. INTERNAL CLUSTER
FAILURE.2.A. PERFORM CLUSTER SELF-DIAGNOSTIC TEST
AND CHECK FOR FAULT CODES.
²IF THE POINTER MOVES DURING TEST BUT
STILL APPEARS ERRATIC, THEN GO TO STEP 2.B.
2.B. REPLACE CLUSTER ASSEMBLY.
RSINSTRUMENT CLUSTER8J-5
INSTRUMENT CLUSTER (Continued)
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CONDITION POSSIBLE CAUSES CORRECTION
SPEEDOMETER
INACCURATE.1. SPEEDOMETER OUT
OF CALIBRATION.1.A. PERFORM CLUSTER SELF-DIAGNOSTIC TEST.
²IF SPEEDOMETER IS ACCURATE TO THE
CALIBRATION POINTS THEN LOOK FOR ANOTHER
POSSIBLE CAUSE OF INACCURACY.
²IF SPEEDOMETER IS NOT ACCURATE TO THE
CALIBRATION POINTS, REPLACE CLUSTER
ASSEMBLY.
2. WRONG
SPEEDOMETER PINION
SIZE FOR TIRE SIZE.2.A. IF VEHICLE HAS A 4 SPEED ELECTRONIC
TRANSMISSION GO TO STEP 2.C. OTHERWISE GO
TO STEP 2.B.
2.B. CHECK IF CORRECT SPEEDOMETER PINION
IS BEING USED WITH TIRES ON VEHICLE. REFER
TO TRANSMISSION FOR DIAGNOSIS AND
TESTING.
²IF THE INCORRECT PINION IS IN TRANSMISSION
THEN REPLACE WITH CORRECT PINION.
²IF THE CORRECT PINION IS IN THE
TRANSMISSION, CHECK TIRE SIZE.
2.C. USE A DRB IIITSCAN TOOL TO CHECK THE
TCM TO SEE IF THE CORRECT TIRE SIZE HAS
BEEN PROGRAMMED INTO THE TCM.
²IF THE INCORRECT TIRE SIZE WAS SELECTED,
SELECT THE PROPER TIRE SIZE.
²IF THE CORRECT TIRE SIZE WAS SELECTED,
CHECK SPEED SENSOR.
3. BAD SPEED SENSOR. 3. REFER TO TRANSMISSION, SPEED SENSOR,
DIAGNOSIS AND TESTING.
TACHOMETER DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
NO POINTER
MOVEMENT1. INTERNAL
CLUSTER FAILURE.1.A. PERFORM CLUSTER SELF-DIAGNOSTIC TEST AND
CHECK FOR FAULT CODES.
²IF TACHOMETER POINTER MOVES TO CALIBRATION
POINTS DURING TEST, LOOK FOR ANOTHER
POSSIBLE CAUSE OF FAILURE.
²
IF THE POINTER DOESN'T MOVE DURING TEST,
CHECK FOR POWER AND GROUND TO THE MIC.
IF POWER AND GROUND ARE PRESENT GO TO
STEP 1.B.
1.B. REPLACE CLUSTER. GO TO STEP 1.C.
2.9NO RPM9PCI BUS
MESSAGE OR9ZERO
RPM9PCI BUS
MESSAGE FROM
PCM.2. CHECK THE PCM USING A DRB IIITSCAN TOOL.
REFER TO THE PROPER ENGINE DIAGNOSTIC
PROCEDURES MANUAL TO PROPERLY DIAGNOSE AND
REPAIR.
8J - 6 INSTRUMENT CLUSTERRS
INSTRUMENT CLUSTER (Continued)
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CONDITION POSSIBLE CAUSES CORRECTION
2. INTERNAL CLUSTER
FAILURE.2. PERFORM CLUSTER SELF-DIAGNOSTIC TEST
AND CHECK FOR FAULT CODES.
²IF THE POINTER MOVES DURING TEST BUT
STILL APPEARS ERRATIC, REPLACE CLUSTER
ASSEMBLY.
FUEL GAUGE
INACCURATE.1. FUEL GAUGE OUT OF
CALIBRATION.1. PERFORM CLUSTER SELF-DIAGNOSTIC TEST. IF
POINTER IS ACCURATE TO THE CALIBRATION
POINTS LOOK FOR ANOTHER POSSIBLE CAUSE
OF FAILURE. IF POINTER IS INACCURATE TO THE
CALIBRATION POINTS, REPLACE CLUSTER
ASSEMBLY.
2. FUEL LEVEL SENDING
UNIT IS OUT OF
CALIBRATION.2. REFER TO THE FUEL SECTION OF THE SERVICE
MANUAL FOR TESTING AND REPAIR PROCEDURE.
TEMPERATURE GAUGE DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
NO POINTER
MOVEMENT1. INTERNAL CLUSTER
FAILURE.1. PERFORM CLUSTER SELF-DIAGNOSTIC TEST
AND CHECK.
²IF TEMPERATURE GAUGE POINTER MOVES TO
CALIBRATION POINTS, LOOK FOR ANOTHER
POSSIBLE CAUSE OF FAILURE.
²IF THE POINTER DOESN'T MOVE DURING TEST,
VERIFY POWER AND GROUND ARE BEING
PROVIDED TO THE CLUSTER. IF YES, REPLACE
CLUSTER. IF NO, DETERMINE CAUSE OF NO
POWER OR NO GROUND.
2. NO PCI
TEMPERATURE
MESSAGE OR COLD PCI
BUS MESSAGE FROM
THE POWERTRAIN
CONTROL MODULE.2.A. CHECK PCM FAULT CODES USING A DRB IIIT
SCAN TOOL. IF THERE ARE NO FAULTS, GO TO
STEP 2.B. IF THERE ARE FAULTS, REFER TO THE
PROPER ENGINE DIAGNOSTIC PROCEDURES
MANUAL TO PROPERLY DIAGNOSE AND REPAIR.
2.B. REFER TO FUEL, COOLANT TEMPERATURE
SENSOR, DIAGNOSIS AND TESTING. REPAIR
SENSOR AS NEEDED.
ERRATIC POINTER
MOVEMENT.1. BAD PCI BUS
MESSAGE FROM THE
POWERTRAIN CONTROL
MODULE.1.A. CHECK PCM FAULT CODES USING A DRB IIIT
SCAN TOOL. IF THERE ARE NO FAULTS, GO TO
STEP 1.B. IF THERE ARE FAULTS, REFER TO THE
ENGINE DIAGNOSTIC PROCEDURES MANUAL TO
PROPERLY DIAGNOSE AND REPAIR.
1.B. REFER TO FUEL, COOLANT TEMPERATURE
SENSOR, DIAGNOSIS AND TESTING. REPAIR
SENSOR AS NEEDED.
2. INTERNAL CLUSTER
FAILURE.2. PERFORM CLUSTER SELF-DIAGNOSTIC TEST
AND CHECK FOR FAULT CODES.
²IF THE POINTER MOVES DURING TEST BUT
STILL APPEARS ERRATIC, REPLACE CLUSTER
ASSEMBLY.
8J - 8 INSTRUMENT CLUSTERRS
INSTRUMENT CLUSTER (Continued)
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CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE
INACCURATE.1. TEMPERATURE
GAUGE OUT OF
CALIBRATION.1. PERFORM CLUSTER SELF-DIAGNOSTIC TEST.
²IF POINTER IS ACCURATE TO THE CALIBRATION
POINTS LOOK FOR ANOTHER POSSIBLE CAUSE
OF FAILURE.
²IF POINTER IS INACCURATE TO THE
CALIBRATION POINTS, REPLACE CLUSTER
ASSEMBLY.
2. COOLANT SENSOR
OUT OF CALIBRATION.2. REFER TO FUEL, COOLANT TEMPERATURE
SENSOR FOR TEST AND REPAIR PROCEDURE.
ODOMETER DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
NO DISPLAY 1. NO PCI BUS
ODOMETER MESSAGE
FROM BCM.1. USE A DRB IIITSCAN TOOL TO CHECK THE
BCM. REFER TO THE PROPER BODY DIAGNOSTIC
PROCEDURES MANUAL TO PROPERLY DIAGNOSE
AND REPAIR.
2. INTERNAL CLUSTER
FAILURE.2. PERFORM CLUSTER SELF-DIAGNOSTIC TEST
AND CHECK FOR FAULT CODES.
²IF ODOMETER PASSES THE SEGMENT CHECK,
LOOK FOR ANOTHER POSSIBLE CAUSE OF
FAILURE. IF IT FAILS VERIFY POWER AND
GROUND ARE BEING PROVIDED TO THE
CLUSTER. IF YES, REPLACE CLUSTER. IF NO,
DETERMINE CAUSE OF NO POWER OR GROUND.
ERRATIC DISPLAY 1. INTERNAL CLUSTER
FAILURE.1.A. PERFORM CLUSTER SELF-DIAGNOSTIC TEST
AND CHECK FOR FAULT CODES.
²IF ODOMETER PASSES THE SEGMENT TEST,
FAILURE MAY NOT BE IN THE CLUSTER. LOOK
FOR ANOTHER POSSIBLE CAUSE OF FAILURE.
VERIFY GOOD POWER AND GROUND
CONNECTIONS. IF CONNECTIONS ARE GOOD AND
NO OTHER PROBLEMS ARE FOUND, REPLACE
CLUSTER ASSEMBLY.
2. BAD PCI BUS
MESSAGE FROM THE
BCM.2. USE A DRB IIITSCAN TOOL TO CHECK THE
BCM. REFER TO THE PROPER BODY DIAGNOSTIC
PROCEDURES MANUAL TO PROPERLY DIAGNOSE
AND REPAIR.
ODOMETER WON'T GO
INTO TRIP MODE.1. TRIP SWITCH
DOESN'T WORK.1. IF CLUSTER WILL NOT GO INTO SELF
DIAGNOSTIC MODE AND CANNOT TOGGLE
BETWEEN ODOMETER AND TRIP ODOMETER,
REPLACE CLUSTER.
TRIP ODOMETER WON'T
RESET.1. RESET SWITCH
DOESN'T WORK.1. IF CLUSTER WILL NOT GO INTO SELF
DIAGNOSTIC MODE AND TRIP ODOMETER WILL
NOT RESET, REPLACE CLUSTER.
RSINSTRUMENT CLUSTER8J-9
INSTRUMENT CLUSTER (Continued)
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INSTRUMENT CLUSTER
TABLE OF CONTENTS
page page
INSTRUMENT CLUSTER
DESCRIPTION............................1OPERATION.............................1
INSTRUMENT CLUSTER
DESCRIPTION
WATER IN FUEL LAMP
The Water In Fuel Lamp is located in the instru-
ment cluster. When moisture is found within the fuel
system, the sensor sends a message via the PCI data
bus to the instrument cluster. The sensor is located
underneath the vehicle, directly above the rear axle.
The sensor is housed within the fuel filter/water sep-
arator assembly cover. The sensor is not serviced sep-
arately. If found defective, the entire assembly cover
must be replaced.
OPERATION
WATER IN FUEL LAMP
The Water In Fuel Sensor is a resistive type
switch. It is calibrated to sense the different resis-
tance between diesel fuel and water. When water
enters the fuel system, it is caught in the bottom of
the fuel filter/water separator assembly, where the
sensor is located. Water has less resistance than die-
sel fuel. The sensor then sends a PCI data bus mes-
sage to the instrument cluster to illuminate the
lamp.
If the lamp is inoperative, perform the self diag-
nostic test on the instrument cluster to check the
lamp operation before continuing diagnosis.
RGINSTRUMENT CLUSTER8Ja-1
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OVERHEAD CONSOLE
TABLE OF CONTENTS
page page
OVERHEAD CONSOLE
DESCRIPTION............................2
OPERATION.............................3
DIAGNOSIS AND TESTING..................3
DIAGNOSIS & TESTING...................3
STANDARD PROCEDURE...................4
COURTESY LAMP REPLACEMENT..........4
COMPASS CALIBRATION..................4
COMPASS DEMAGNETIZING...............4
COMPASS VARIATION ADJUSTMENT........5
REMOVAL...............................6
INSTALLATION............................6
ELECTRONIC VEHICLE INFO CENTER
DESCRIPTION............................6
OPERATION.............................7
DIAGNOSIS AND TESTING..................7
TRAVELER MESSAGES...................7
STANDARD PROCEDURE...................8
EVIC PROGRAMMING....................8
REMOVAL...............................9
INSTALLATION............................9COMPASS/MINI-TRIP COMPUTER
DESCRIPTION............................9
OPERATION.............................10
DIAGNOSIS AND TESTING.................10
DIAGNOSIS AND TESTING...............10
REMOVAL..............................10
INSTALLATION...........................10
UNIVERSAL TRANSMITTER
DESCRIPTION...........................10
OPERATION.............................10
DIAGNOSIS AND TESTING.................11
UNIVERSAL GARAGE DOOR OPENER......11
AMBIENT TEMP SENSOR
DESCRIPTION...........................11
OPERATION.............................11
DIAGNOSIS AND TESTING.................11
AMBIENT TEMPERATURE SENSOR.........11
AMBIENT TEMPERATURE SENSOR
CIRCUIT..............................11
REMOVAL..............................12
INSTALLATION...........................12
OVERHEAD CONSOLE
DESCRIPTION
The available overhead consoles on RS models can
include the Electronic Vehicle Information Center
(EVIC), Compass Mini-Trip Computer (CMTC) or a
Compass Temperature Computer (CT). All consoles
are equipped with two reading/courtesy lamps and if
the vehicle is equipped with a power liftgate or
power sliding door(s) the overhead console will also
include command switches for these features. The
overhead console is mounted with one screw and two
snap clips to a molded plastic retainer bracket
located above the headliner.
DESCRIPTION - COMPASS
All the available overhead consoles on this model
include Compass information. While in the compass/
thermometer mode, the compass will display the
direction in which the vehicle is pointed using the
eight major compass headings (Examples: north is N,
northeast is NE). The self-calibrating compass unit
requires no adjusting in normal use. The only cali-
bration that may prove necessary is to drive the vehi-
cle in three complete circles at 5 to 8 kilometers-per-
hour (3 to 5 miles-per-hour), on level ground, in notless than forty-eight seconds. This will reorient the
compass unit to its vehicle.
The compass unit also will compensate for magne-
tism the body of the vehicle may acquire during nor-
mal use. However, avoid placing anything magnetic
directly on the roof of the vehicle. Magnetic mounts
for an antenna, a repair order hat, or a funeral pro-
cession flag can exceed the compensating ability of
the compass unit if placed on the roof panel. Mag-
netic bit drivers used on the fasteners that hold the
overhead console assembly to the roof header can
also affect compass operation. If the vehicle roof
should become magnetized, the demagnetizing and
calibration procedures found in this section may be
required to restore proper compass operation.DESCRIPTION - THERMOMETER
All the available overhead consoles on this model
include Temperature information. The thermometer
displays the outside ambient temperature in whole
degrees. The temperature display can be toggled
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 thermometer display several minutes
to respond to a major temperature change, such as
8M - 2 OVERHEAD CONSOLERS
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driving out of a heated garage into winter tempera-
tures.
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 thermometer function is supported by an
ambient temperature sensor. The sensor is mounted
outside the passenger compartment near the front
and center of the vehicle, and is hard wired to the
Front Control Module (FCM). The FCM sends tem-
perature 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 & TESTING - OVERHEAD
CONSOLE
If the problem with the overhead console is an
inaccurate or scrambled display, refer toSelf-Diag-
nostic Testlater in this group. 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 Control Module (FCM) over the J1850 Pro-
grammable Communications Interface (PCI) data bus
circuit. If the problem is a no-display condition, use
the following procedures. For complete circuit dia-
grams, refer toOverhead Consolein the Wiring
Diagrams section of the service manual.
(1) Check the fused B(+) fuse in the intelligent
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 intelligent power module. If OK, go to Step 3.
If not OK, repair the open fused B(+) circuit to the
fused B(+) fuse in the intelligent power module as
required.
(3) Check the fused ignition switch output (run/
start) fuse in the intelligent 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 switchoutput (run/start) fuse in the intelligent 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 intel-
ligent 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 intelligent 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:
²Pass Self Test (EVIC only), PASS (CT,
CMTC)- The electronics module is working properly.
²Failed Self Test (EVIC only), FAIL (CT,
CMTC)- The electronics module has an internal fail-
ure. The electronics module is faulty and must be
replaced.
²Failed 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
RSOVERHEAD CONSOLE8M-3
OVERHEAD CONSOLE (Continued)
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