2002 CHRYSLER CARAVAN manual transmission

(a) Align the valve notch in the wheel cover with
the valve stem on the wheel.
(b) At the same time, align the two holes in the
wheel cover having the retaining tabs with the two
installed wheel nuts (Fig. 15).
(c) Press in on center of wheel cover until wheel
cover retaining tabs push past and engage rear of
previously installed wheel mounting nuts (Fig. 15).
This will hold the wheel cover in place.
(4) Install andlightly tightenthe three remain-
ing wheel mounting nuts, securing the wheel cover in
place (Fig. 12).
(5) Progressively tighten all five wheel mounting
nuts in the proper sequence (Fig. 16). Tighten wheel
nuts to a torque of 135 N´m (100 ft. lbs.).
(6) Lower the vehicle.TIRE PRESSURE MONITORING
(TPM)
DESCRIPTION
Some versions of this vehicle are equipped with a
Tire Pressure Monitoring (TPM) system. It monitors
air pressure in the four road tires (excludes spare).
Pressure in the spare tire is not monitored.
There is a sensor (transmitter) in each of the vehi-
cle's four road wheels. The system alerts the driver
when tire pressure falls outside predetermined
thresholds (pressure too low or too high). A message
is then displayed on the Electronic Vehicle Informa-
tion Center (EVIC) located in the overhead console.
For further information, refer to the Owners Man-
ual or the appropriate diagnostic information.
OPERATION
The Tire Pressure Monitoring (TPM) system uses
radio and sensor technology to monitor tire air pres-
sure levels. Sensors, mounted to each road wheel as
part of the valve stem, transmit tire pressure read-
ings to a receiver located in the overhead console.
These transmissions occur once every minute at
speeds over 20 mph (32 km/h). The Tire Pressure
Monitoring system remains active even if no tire
pressure related message is displayed in the EVIC.
If any road tire pressure has exceeded the low or
high pressure threshold (refer to chart below), the
TPM system will display a message in the EVIC and
sound a chime. This message will be displayed for
the rest of the ignition cycle, or until either the Low/
High Tire pressure condition has been corrected. If
the C/T, MENU, STEP or RESET button is pressed,
the message is replaced by the new message
requested; however, if the Low/High Tire condition
has not been corrected, the Low/High Tire pressure
message will again be displayed.
If a road tire is replaced by the spare, the TPM
system will detect the swap and the message9SPARE
TIRE IN USE? Y/N9(along with a chime) will be dis-
played.
For further information, refer to the Owners Man-
ual or the Appropriate Diagnostic Information.
TPM THRESHOLD PRESSURES
High Pressure ON Threshold 48 PSI (331 kPa)
High Pressure OFF Threshold 43 PSI (296 kPa)
Placard Pressure (Cold) 36 PSI (248 kPa)
Low Pressure OFF Threshold 33 PSI (228 kPa)
Low Pressure ON Threshold 28 PSI (193 kPa)
Fig. 15 WHEEL COVER INSTALLATION OVER TWO
NUTS
1 - RETAINING TABS
2 - VALVE STEM
3 - BOLT-ON WHEEL COVER
Fig. 16 NUT TIGHTENING SEQUENCE
RSTIRES/WHEELS22-9
TIRES/WHEELS (Continued)
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SENSOR - TPM
DESCRIPTION
On vehicles equipped with Tire Pressure Monitor-
ing, one tire pressure sensor is mounted to each
wheel (Fig. 19). Each sensor has an internal battery
that lasts up to 10 years. The battery is not service-
able. At the time of battery failure, the sensor must
be replaced. The serviceable components of the tire
pressure sensor are:
²Sensor-To-Wheel Grommet
²Valve Stem Cap
²Valve Stem Core
Valve stem caps and cores are specifically designed
for the tire pressure monitoring sensors. Although
similar to standard valve stem caps and cores, they
are different.
CAUTION: Do not use a standard valve stem cap or
core in a tire pressure sensor. Always use the orig-
inal equipment style sensor cap and core.
CAUTION: Do not reuse the Sensor-To Wheel Grom-
met. Always use a new grommet when installing a
pressure sensor and properly torque the sensor
nut.
CAUTION: Do not try to install a tire pressure sen-
sor in a steel wheel or aftermarket wheel. Use only
in original style factory wheels.
OPERATION
Tire pressure sensors are battery operated. They
transmit tire pressure data once every minute at
speeds above 20 mph (32 km/h) or up to once every
hour when stationary (parked). For additional infor-
mation, refer to Appropriate Diagnostic Information.
CAUTION
CAUTION: The use of tire sealants is strictly prohib-
ited for vehicles equipped with the Tire Pressure
Monitoring system. Tire sealants can clog tire pres-
sure sensors.
CAUTION: Tire pressure sensor valve stem caps
and cores are specially designed for the sensors.
Due to risk of corrosion, do not use a standard
valve stem cap or core in a tire pressure sensor in
place of the original equipment style sensor cap
and core.CAUTION: Do not attempt to install a tire pressure
sensor in a steel wheel or aftermarket wheel. Use
tire pressure sensors in original style factory
wheels only.
NOTE: TPM thresholds have been established for
the original tire size equipped on the vehicle. Use
original size tires only to maintain system accuracy.
DIAGNOSIS AND TESTING - TIRE PRESSURE
SENSOR
NOTE: Tire pressure may increase from 2 to 6 psi
(14 to 41 kPa) during normal driving conditions. Do
NOT reduce this normal pressure build up.
If a fault in the system is detected, always check
air pressure in the tires first with a known accurate
air gauge and correct the inflation pressure. If any
tire is low, inspectalltires.
If gauge-read pressure in the tires does not reflect
the reading on the EVIC, retrain the sensors, then
reevaluate (Refer to 22 - TIRES/WHEELS/TIRE
PRESSURE MONITORING/SENSOR - STANDARD
PROCEDURE). Refer to the appropriate diagnostic
information for complete diagnosis of the Tire Pres-
sure Monitoring System.
STANDARD PROCEDURE - TIRE PRESSURE
SENSOR RETRAIN
WARNING: DEATH OR SERIOUS INJURY CAN
OCCUR IF MAGNETICALLY SENSITIVE DEVICES
ARE EXPOSED TO THE RELEARN MAGNET. MAG-
NETS CAN AFFECT PACEMAKERS.
CAUTION: Never attempt to train more than one
vehicle at a time. System is capable of reading tire
pressure sensor transmissions from other near-by
vehicles.
Each time a wheel rotation or tire pressure sensor
replacement occurs the tire pressure sensors must be
retrained. This is necessary to inform the Electronic
Vehicle Information Center (EVIC) that a sensor
change was made and where. Retraining is accom-
plished through the EVIC used in conjunction with a
Re-learn Magnet, Special Tool 8821.
22 - 10 TIRES/WHEELSRS
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INSTALLATION
(1) Install the glove box latch striker.
(2) Install the screws holding latch striker to
instrument panel.
(3) Close glove box door.
INSTRUMENT PANEL
ASSEMBLY
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the lower console:
(a) Remove six retaining screws.
(b) Pull rearward and disconnect the auxiliary
power outlet.
(c) Remove lower console from vehicle.
(3) Remove the bolts attaching the lower supports
to the instrument panel frame (Fig. 3).
(4) Remove the bolts attaching the lower supports
to the floor pan.
(5) Disconnect the wire connectors from the Pas-
senger Airbag.
(6) Remove the two screws to each right and left
cowl trim covers.
(7) Remove the both left and right side A-pillar
trim covers using a trim stick (special tool #C-4755)
or equivalent gently pry out on the trim covers and
remove.
(8) Remove the glove box:
(a) Push in on sides of glove box bin and lower
door.
(b) Pivot glove box downward and disengage
hinge hooks from instrument panel.
(c) Remove glove box from vehicle.
(9) Disconnect the antenna lead connector from
behind the glove box.
(10) Remove the four screws to the lower steering
column cover.
(11) Remove the eight screws to the steering col-
umn backing plate.
(12) Unclip the Data Link Connector (DLC) from
the steering column backing plate.
(13) Remove two screws to the left side instrument
panel silencer and remove (Fig. 4).
(14) Disconnect the left side wiring:
(a) Brake switch.
(b) Main bulkhead connector.
(c) Five harness connectors.
(d) Driver airbag connector.
(15) Remove the two screws to the hood release
handle.
(16) Remove five screws to steering column back-
ing plate and remove (Refer to 23 - BODY/INSTRU-
MENT PANEL/KNEE BLOCKER - REMOVAL).(17) Remove the two steering column shroud
retaining screws. Separate the shrouds and remove
from vehicle.
(18) Remove the screws attaching the instrument
panel reinforcement and remove (Fig. 5).
(19) Disconnect the steering column wiring. There
are seven connectors and then unclip the harness
from the column.
(20) Disconnect the Occupant Restraint Controller
(ORC) harness connector.
(21) Remove the four nuts retaining the steering
column to the dash panel steering column mounting
bracket and lower column to the floor (Fig. 6).
(22) Remove the four nuts attaching the instru-
ment panel to the brake pedal support bracket.
(23) Loosen the left side roll down bolt (Fig. 7).
(24) Remove the left side A-pillar retaining bolts.
There are two 13 mm bolts and one 10 mm bolt.
(25) If equipped with a mechanical transmission
range indicator:
(a) Remove the indicator cable loop.
(b) Remove the clip holding gear shift cable end
to the gear selector adapter.
(c) Pull the cable end from gear selector.
(d) Disconnect the clip for the indicator cable
and guide tube from the shift cable bracket and
move out of the way.
(26) Remove the instrument panel top cover. Using
a trim stick or equivalent, gently pry up on the front
edge of the top cover, pull rearward and remove from
vehicle.
(27) Disconnect the right side wire connectors from
the HVAC behind the glove box area and the two
antenna connectors behind the glove box hinge.
(28) Remove the right end cover by pulling out-
board.
(29) Remove the right side A-pillar retaining bolts.
There are two 13 mm bolts and one 10 mm bolt.
(30) Loosen the right side roll down bolt.
(31) Disconnect the two front window defroster
grid wire connectors. One on each side of vehicle.
(32) Remove both the left and right power mirrors:
(a) Using a trim stick or equivalent, gently pry
out on mirror trim cover.
(b) Open door and remove the three torx retain-
ing screws.
(c) Disconnect the wire connector and remove
mirror from the vehicle.
(33) Feed power mirror wire harness inboard
through the A-pillar.
(34) Remove the bolts attaching the instrument
panel frame to the dash panel below windshield
opening.
(35) With the help of an assistant remove the
instrument panel from vehicle. Lift the instrument
RSINSTRUMENT PANEL23-65
GLOVE BOX LATCH STRIKER (Continued)
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INSTALLATION
(1) With the help of an assistant place the instru-
ment panel into vehicle on roll down bolts. As you
roll the instrument panel up, lift the instrument
panel up so the duct work does not bind or bend and
you can set it down on the HVAC housing to get the
proper seal at the distribution duct. Get one bolt
started in the dash panel.
(2) Install the left and right side A-pillar retaining
bolts. There are two 13 mm bolts and one 10 mm
bolt. The 10 mm bolts need to be installed first to
insure proper positioning of the Instrument panel in
the vehicle. Start the right side 10 mm bolt first (Fig.
7).
(3) Feed power mirror wire harness outboard
through the A-pillar.
(4) Install both the left and right power mirrors:
(a) Connect the wire connector and install the
mirror onto the vehicle.
(b) Install the three torx retaining screws.
(c) Using a firm push, snap the mirror trim
cover into place.
(5) Connect the two front window defroster grid
wire connectors. One on each side of vehicle.
(6) Tighten the right side roll down bolt.
(7) Install the right end cover. Position over retain-
ing slots and firmly snap into place.(8) Connect the right side wire connectors to the
HVAC behind the glove box area and the two
antenna connectors behind the glove box hinge.
(9) Install the bolts attaching the instrument
panel frame to the dash panel below windshield
opening.
(10) Install the instrument panel top cover. Slide
the front edge of the top cover toward dash panel,
and firmly snap down the rear edge of the to cover to
engage clips.
(11) If equipped with a mechanical transmission
range indicator:
(a) Connect the clip for the indicator cable and
guide tube to the shift cable bracket.
(b) Install the cable end to the gear selector.
(c) Install the clip holding the gear shift cable
end to the gear selector adapter.
(d) Install the indicator cable loop.
(12) Tighten the left side roll down bolt.
(13) Install the four nuts attaching the instrument
panel to the brake pedal support bracket.
(14) Install the four nuts retaining the steering
column and lower to the floor (Fig. 6).
(15) Connect the Occupant Restraint Controller
(ORC) harness connector.
(16) Connect the steering column wiring. There
are seven connectors and then clip the harness to the
column.
Fig. 7 INSTRUMENT PANEL REMOVAL
1 - INSTRUMENT PANEL
2 - FIVE ATTACHING SCREWS
3 - 13 mm BOLT - TWO ON EACH SIDE4 - ROLL DOWN BRACKET
5 - 10 mm BOLT - STARTING BOLT ONE EACH SIDE
RSINSTRUMENT PANEL23-67
INSTRUMENT PANEL ASSEMBLY (Continued)
ProCarManuals.com

FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM CHARGE).
INSTALLATION - COMPRESSOR MOUNTING
BRACKET - 2.4L ENGINE
(1) Position the compressor mounting bracket onto
the engine.
(2) Install and tighten the four screws that secure
the compressor mounting bracket to the engine.
Tighten the screws to 54 N´m (40 ft. lbs.).
(3) Reinstall the compressor onto the mounting
bracket. (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING/COMPRESSOR - INSTALLA-
TION).
CONDENSER
DESCRIPTION
The condenser is integral to a cooling module
which includes the radiator, the electric cooling fan,
the fan shroud, air seals and an automatic transmis-
sion oil cooler. The cooling module is located in the
air flow in the front of the engine compartment
behind the radiator grille. The condenser cannot be
repaired or adjusted and, if faulty or damaged, it
must be replaced. The condenser may be removed
from the cooling module for service without removing
the cooling module from the vehicle.
OPERATION
The condenser is a heat exchanger that allows the
high-pressure refrigerant gas being discharged by the
compressor to give up its heat to the air passing over
the condenser fins. When the refrigerant gas gives up
its heat, it condenses. When the refrigerant leaves
the condenser, it has become a high-pressure liquid
refrigerant. The volume of air flowing over the con-
denser fins is critical to the proper cooling perfor-
mance of the air conditioning system. Therefore, it is
important that there are no objects placed in front of
the radiator grille openings in the front of the vehicle
or foreign material on the condenser fins that might
obstruct air flow. Also, any factory-installed air seals
or shrouds must be properly reinstalled following
radiator or condenser service.
REMOVAL
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - WARNING - A/C PLUMBING)
and (Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - CAUTION - A/C PLUMBING).NOTE: Before removing the condenser, note the
location of each of the radiator and condenser air
seals. These air seals are used to direct air through
the condenser and radiator. The air seals must be
reinstalled in their proper locations in order for the
air conditioning and engine cooling systems to per-
form as designed.
(1) Recover the refrigerant from the refrigerant
system. (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING - FRONT/REFRIGERANT -
STANDARD PROCEDURE - REFRIGERANT
RECOVERY).
(2) Remove the two large screws that secure the
front fascia and the outboard ends of the radiator
sight shield to the radiator closure panel crossmem-
ber (Fig. 4).
(3) Remove the five small screws that secure the
front fascia grille inserts to the radiator sight shield.
(4) Remove the radiator sight shield from the radi-
ator closure panel crossmember.
(5) Remove the two screws that secure the hood
latch unit to the front of the radiator closure panel
crossmember and move the latch out of the way over
the top of the crossmember. Mark the location of
latch for reinstallation.
(6) Disconnect the hoses from the transmission oil
cooler fittings on the left side of the cooling module.
(Refer to 7 - COOLING/TRANSMISSION/TRANS
COOLER LINES - REMOVAL).
(7) Remove the nut that secures the discharge line
fitting to the condenser on the right side of the cool-
ing module.
Fig. 4 Radiator Sight Shield
1 - LARGE SCREWS (2)
2 - SMALL SCREWS (5)
3 - RADIATOR SIGHT SHIELD
4 - GRILLE INSERTS
5 - FRONT FASCIA
RSPLUMBING - FRONT24-65
COMPRESSOR (Continued)
ProCarManuals.com

(8) Disconnect the discharge line fitting from the
condenser inlet port.
(9) Remove the seal from the discharge line fitting
and discard.
(10) Install plugs in, or tape over the opened dis-
charge line fitting and the condenser inlet port.
(11) Remove the nut that secures the liquid line
fitting to the condenser on the right side of the cool-
ing module.
(12) Disconnect the liquid line fitting from the con-
denser outlet port.
(13) Remove the seal from the liquid line fitting
and discard.
(14) Install plugs in, or tape over the opened liquid
line fitting and the condenser outlet port.
(15) Remove the screw that secures the top of the
mounting bracket on each side of the condenser to
the cooling module (Fig. 5).
(16) Lift the condenser, transmission oil cooler, and
mounting brackets as a unit far enough to disengage
the locating pin that secures the mounting brackets
in the lower mount rubber isolators on each side of
the cooling module.
(17) Remove the condenser, transmission oil cooler,
and mounting brackets from the vehicle as a unit.(18) Remove the two screws that secure each
mounting bracket to the sides of the condenser.
(19) Remove the one screw that secures the left
mounting bracket to the side of the transmission oil
cooler.
(20) Remove the left mounting bracket from the
side of the condenser and transmission oil cooler.
(21) Remove the condenser from the right mount-
ing bracket and transmission oil cooler unit.
INSTALLATION
NOTE: If the condenser is being replaced, add 30
milliliters (1 fluid ounce) of refrigerant oil to the
refrigerant system. Use only refrigerant oil of the
type recommended for the compressor in the vehi-
cle.
NOTE: Be certain that each of the radiator and con-
denser air seals are reinstalled in their proper loca-
tions. These air seals are required in order for the
air conditioning and engine cooling systems to per-
form as designed.
(1) Position the condenser to the right mounting
bracket and transmission oil cooler unit.
(2) Position the left mounting bracket onto the side
of the condenser and transmission oil cooler.
(3) Install and tighten the one screw that secures
the left mounting bracket to the side of the transmis-
sion oil cooler. Tighten the screw to 5 N´m (45 in.
lbs.).
(4) Install and tighten the two screws that secure
each mounting bracket to the sides of the condenser.
Tighten the screws to 5 N´m (45 in. lbs.).
(5) Position the condenser, transmission oil cooler,
and mounting brackets into the vehicle as a unit. Be
certain that the locating pins that secure the mount-
ing brackets are engaged in the lower mount rubber
isolators on each side of the cooling module.
NOTE: Verify that the condensor isolators are all
installed and positioned correctly.
(6) Install and tighten the two screws that secure
the top of the mounting bracket on each side of the
condenser to the cooling module. Tighten the screws
to 5 N´m (45 in. lbs.).
(7) Remove the tape or plugs from the condenser
outlet port and the liquid line fitting.
(8) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the liquid line fitting.
(9) Reconnect the liquid line fitting to the con-
denser outlet port on the right side of the cooling
module.
Fig. 5 Condenser Mounting
1 - SCREW (2)
2 - LOWER MOUNT ISOLATOR (2)
3 - CONDENSER
24 - 66 PLUMBING - FRONTRS
CONDENSER (Continued)
ProCarManuals.com

(10) Install and tighten the nut that secures the
liquid line fitting to the condenser. Tighten the nut to
23 N´m (17 ft. lbs.).
(11) Remove the tape or plugs from the condenser
inlet port and the discharge line fitting.
(12) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the discharge line fit-
ting.
(13) Reconnect the discharge line fitting to the
condenser inlet port on the right side of the cooling
module.
(14) Install and tighten the nut that secures the
discharge line fitting to the condenser. Tighten the
nut to 23 N´m (17 ft. lbs.).
(15) Reconnect the hoses to the transmission oil
cooler fittings on the left side of the cooling module.
(Refer to 7 - COOLING/TRANSMISSION/TRANS
COOLER LINES - INSTALLATION).
(16) Reposition the hood latch unit to the front of
the radiator closure panel crossmember.
(17) Install and tighten the two screws that secure
the hood latch unit to the front of the radiator clo-
sure panel crossmember. Check and adjust the hood
latch as needed. Tighten the screws to 14 N´m (123
in. lbs.).
(18) Position the radiator sight shield onto the
radiator closure panel crossmember.
(19) Install and tighten the five small screws that
secure the front fascia grille inserts to the radiator
sight shield. Tighten the screws to 2 N´m (18 in. lbs.).
(20) Install and tighten the two large screws that
secure the front fascia and the outboard ends of the
radiator sight shield to the radiator closure panel
crossmember. Tighten the screws to 6 N´m (53 in.
lbs.).
(21) Evacuate the refrigerant system. (Refer to 24
- HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM EVACUATE).
(22) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM CHARGE).
DISCHARGE LINE
REMOVAL
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - WARNING - A/C PLUMBING)
and (Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - CAUTION - A/C PLUMBING).(1) Recover the refrigerant from the refrigerant
system. (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING - FRONT/REFRIGERANT -
STANDARD PROCEDURE - REFRIGERANT
RECOVERY).
(2) Remove the two large screws that secure the
front fascia and the outboard ends of the radiator
sight shield to the radiator closure panel crossmem-
ber (Fig. 6).
(3) Remove the five small screws that secure the
front fascia grille inserts to the radiator sight shield.
(4) Remove the radiator sight shield from the radi-
ator closure panel crossmember.
(5) Remove the nut that secures the discharge line
fitting to the condenser on the right side of the cool-
ing module (Fig. 7).
(6) Disconnect the discharge line fitting from the
condenser inlet port.
(7) Remove the seal from the discharge line fitting
and discard.
(8) Install plugs in, or tape over the opened dis-
charge line fitting and the condenser inlet port.
(9) Remove the nut that secures the discharge line
fitting to the top of the compressor (Fig. 8).
(10) Disconnect the discharge line fitting from the
compressor discharge port.
(11) Remove the seal from the discharge line fit-
ting and discard.
(12) Install plugs in, or tape over the opened dis-
charge line fitting and the compressor discharge port.
(13) Remove the discharge line from the engine
compartment.
Fig. 6 Radiator Sight Shield
1 - LARGE SCREWS (2)
2 - SMALL SCREWS (5)
3 - RADIATOR SIGHT SHIELD
4 - GRILLE INSERTS
5 - FRONT FASCIA
RSPLUMBING - FRONT24-67
CONDENSER (Continued)
ProCarManuals.com

ªBig Slopeº. The PCM checks the oxygen sensor volt-
age in increments of a few milliseconds.
Reduced Output Voltage (Half Cycle)ÐThe
output voltage of the O2S ranges from 0 to 1 volt. A
good sensor can easily generate any output voltage in
this range as it is exposed to different concentrations
of oxygen. To detect a shift in the A/F mixture (lean
or rich), the output voltage has to change beyond a
threshold value. A malfunctioning sensor could have
difficulty changing beyond the threshold value. Each
time the voltage signal surpasses the threshold, a
counter is incremented by one. This is called the Half
Cycle Counter.
Heater PerformanceÐThe heater is tested by a
separate monitor. Refer to the Oxygen Sensor Heater
Monitor.
OPERATIONÐAs the Oxygen Sensor signal
switches, the PCM monitors the half cycle and big
slope signals from the oxygen sensor. If during the
test neither counter reaches a predetermined value, a
malfunction is entered and Freeze Frame data is
stored. Only one counter reaching its predetermined
value is needed for the monitor to pass.
The Oxygen Sensor Monitor is a two trip monitor
that is tested only once per trip. When the Oxygen
Sensor fails the test in two consecutive trips, the
MIL is illuminated and a DTC is set. The MIL is
extinguished when the Oxygen Sensor monitor
passes in three consecutive trips. The DTC is erased
from memory after 40 consecutive warm-up cycles
without test failure.
Enabling ConditionsÐThe following conditions
must typically be met for the PCM to run the oxygen
sensor monitor:
²Battery voltage
²Engine temperature
²Engine run time
²Engine run time at a predetermined speed
²Engine run time at a predetermined speed and
throttle opening
²Transmission in gear and brake depressed (auto-
matic only)
²Fuel system in Closed Loop
²Long Term Adaptive (within parameters)
²Power Steering Switch in low PSI (no load)
²Engine at idle
²Fuel level above 15%
²Ambient air temperature
²Barometric pressure
²Engine RPM within acceptable range of desired
idle
Pending ConditionsÐThe Task Manager typi-
cally does not run the Oxygen Sensor Monitor if over-
lapping monitors are running or the MIL is
illuminated for any of the following:
²Misfire Monitor²Front Oxygen Sensor and Heater Monitor
²MAP Sensor
²Vehicle Speed Sensor
²Engine Coolant Temperature Sensor
²Throttle Position Sensor
²Engine Controller Self Test Faults
²Cam or Crank Sensor
²Injector and Coil
²Idle Air Control Motor
²EVAP Electrical
²EGR Solenoid Electrical (if equipped)
²Intake/inlet Air Temperature
²5 Volt Feed
ConflictÐThe Task Manager does not run the
Oxygen Sensor Monitor if any of the following condi-
tions are present:
²A/C ON (A/C clutch cycling temporarily sus-
pends monitor)
²Purge flow in progress
²Ethanel content learn is takeng place and the
ethenal used once flag is set (if equipped)
SuspendÐThe Task Manager suspends maturing
a fault for the Oxygen Sensor Monitor if any of the
following are present:
²Oxygen Sensor Heater Monitor, Priority 1
²Misfire Monitor, Priority 2
OXYGEN SENSOR HEATER MONITOR
DESCRIPTIONÐIf there is an oxygen sensor
(O2S) DTC as well as a O2S heater DTC, the O2S
fault MUST be repaired first. After the O2S fault is
repaired, verify that the heater circuit is operating
correctly.
The voltage readings taken from the O2S are very
temperature sensitive. The readings are not accurate
below 300ÉC. Heating of the O2S is done to allow the
engine controller to shift to closed loop control as
soon as possible. The heating element used to heat
the O2S must be tested to ensure that it is heating
the sensor properly.
The heater element itself is not tested. The sensor
output is used to test the heater by isolating the
effect of the heater element on the O2S output volt-
age from the other effects. The resistance is normally
between 100 ohms and 4.5 megaohms. When oxygen
sensor temperature increases, the resistance in the
internal circuit decreases. The PCM sends a 5 volts
biased signal through the oxygen sensors to ground
this monitoring circuit. As the temperature increases,
resistance decreases and the PCM detects a lower
voltage at the reference signal. Inversely, as the tem-
perature decreases, the resistance increases and the
PCM detects a higher voltage at the reference signal.
The O2S circuit is monitored for a drop in voltage.
OPERATIONÐThe Oxygen Sensor Heater Moni-
tor begins after the ignition has been turned OFF.
RSEMISSIONS CONTROL25-3
EMISSIONS CONTROL (Continued)
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