obd JEEP LIBERTY 2002 KJ / 1.G User Guide

The ACM housing also has an integral ground lug
with a tapped hole that protrudes from the lower left
rear corner of the unit. This lug provides a case
ground to the ACM when a ground screw is installed
through the left side of the mounting bracket. Two
molded plastic electrical connector receptacles exit
the right side of the ACM housing. The smaller of the
two receptacles contains twelve terminal pins, while
the larger one contains twenty-three. These terminal
pins connect the ACM to the vehicle electrical system
through two dedicated take outs and connectors of
the instrument panel wire harness.
A molded rubber protective cover is installed
loosely over the ACM to protect the unit from con-
densation or coolant leaking from a damaged or
faulty heater-air conditioner unit housing. An inte-
gral flange on the left side of the cover is secured to
the floor panel transmission tunnel with a short
piece of double-faced tape as an assembly aid during
the manufacturing process, but this tape does not
require replacement following service removal.
The impact sensor and safing sensor internal to
the ACM are calibrated for the specific vehicle, and
are only serviced as a unit with the ACM. The ACM
cannot be repaired or adjusted and, if damaged or
faulty, it must be replaced. The ACM cover is avail-
able for separate service replacement.
OPERATION
The microprocessor in the Airbag Control Module
(ACM) contains the front supplemental restraint sys-
tem logic circuits and controls all of the front supple-
mental restraint system components. The ACM uses
On-Board Diagnostics (OBD) and can communicate
with other electronic modules in the vehicle as well
as with the DRBIIItscan tool using the Programma-
ble Communications Interface (PCI) data bus net-
work. This method of communication is used for
control of the airbag indicator in the ElectroMechani-
cal Instrument Cluster (EMIC) and for supplemental
restraint system diagnosis and testing through the
16-way data link connector located on the driver side
lower edge of the instrument panel. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER/AIRBAG
INDICATOR - OPERATION).
The ACM microprocessor continuously monitors all
of the front supplemental restraint system electrical
circuits to determine the system readiness. If the
ACM detects a monitored system fault, it sets an
active and stored Diagnostic Trouble Code (DTC) and
sends electronic messages to the EMIC over the PCI
data bus to turn on the airbag indicator. An active
fault only remains for the duration of the fault or in
some cases the duration of the current ignition
switch cycle, while a stored fault causes a DTC to be
stored in memory by the ACM. For some DTCs, if afault does not recur for a number of ignition cycles,
the ACM will automatically erase the stored DTC.
For other internal faults, the stored DTC is latched
forever.
On models equipped with optional side curtain air-
bags, the ACM communicates with both the left and
right Side Impact Airbag Control Modules (SIACM)
over the PCI data bus. The SIACM notifies the ACM
when it has detected a monitored system fault and
stored a DTC in memory for its respective side cur-
tain airbag system, and the ACM sets a DTC and
controls the airbag indicator operation accordingly.
The ACM also monitors a Hall effect-type seat belt
switch located in the buckle of each front seat belt to
determine whether the seatbelts are buckled, and
provides an input to the EMIC over the PCI data bus
to control the seatbelt indicator operation based upon
the status of the driver side front seat belt switch.
The ACM receives battery current through two cir-
cuits; a fused ignition switch output (run) circuit
through a fuse in the Junction Block (JB), and a
fused ignition switch output (run-start) circuit
through a second fuse in the JB. The ACM has a case
ground through a lug on the bottom of the ACM
housing that is secured with a ground screw to the
left side of the ACM mounting bracket. The ACM
also receives a power ground through a ground cir-
cuit and take out of the instrument panel wire har-
ness. This take out has a single eyelet terminal
connector that is secured by a second ground screw
to the left side of the ACM mounting bracket. These
connections allow the ACM to be operational when-
ever the ignition switch is in the Start or On posi-
tions. The ACM also contains an energy-storage
capacitor. When the ignition switch is in the Start or
On positions, this capacitor is continually being
charged with enough electrical energy to deploy the
airbags for up to one second following a battery dis-
connect or failure. The purpose of the capacitor is to
provide backup supplemental restraint system pro-
tection in case there is a loss of battery current sup-
ply to the ACM during an impact.
Two sensors are contained within the ACM, an
electronic impact sensor and a safing sensor. The
ACM also monitors inputs from two remote front
impact sensors located on the back of the right and
left vertical members of the radiator support near
the front of the vehicle. The electronic impact sensors
are accelerometers that sense the rate of vehicle
deceleration, which provides verification of the direc-
tion and severity of an impact. The safing sensor is
an electromechanical sensor within the ACM that
provides an additional logic input to the ACM micro-
processor. The safing sensor is a normally open
switch that is used to verify the need for an airbag
deployment by detecting impact energy of a lesser
8O - 10 RESTRAINTSKJ
AIRBAG CONTROL MODULE (Continued)

(10) Reinstall the headliner into the vehicle. (Refer
to 23 - BODY/INTERIOR/HEADLINER - INSTALLA-
TION).
(11) Reinstall the lower trim onto the inside of the
B-pillar. (Refer to 23 - BODY/INTERIOR/B-PILLAR
LOWER TRIM - INSTALLATION).
(12) Do not reconnect the battery negative cable at
this time. The airbag system verification test proce-
dure should be performed following service of any
supplemental restraint system component. (Refer to
8 - ELECTRICAL/RESTRAINTS - STANDARD PRO-
CEDURE - VERIFICATION TEST).
SIDE IMPACT AIRBAG
CONTROL MODULE
DESCRIPTION
On vehicles equipped with the optional side curtain
airbags, a Side Impact Airbag Control Module
(SIACM) and its mounting bracket are secured with
four screws to the sill panel at the base of each B-pil-
lar behind the lower B-pillar trim (Fig. 43). Con-
cealed within a hollow in the center of the die cast
aluminum SIACM housing is the electronic circuitry
of the SIACM which includes a microprocessor and
an electronic impact sensor. The SIACM housing is
secured to a stamped steel mounting bracket, which
is unique for the right or left side application of this
component. The SIACM should never be removed
from its mounting bracket. The housing also receives
a case ground through this mounting bracket when it
is secured to the vehicle. A molded plastic electrical
connector receptacle that exits the top of the SIACMhousing connects the unit to the vehicle electrical
system through a dedicated take out and connector of
the body wire harness. Both the SIACM housing and
its electrical connection are sealed to protect the
internal electronic circuitry and components against
moisture intrusion.
The impact sensor internal to the SIACM is cali-
brated for the specific vehicle, and is only serviced as
a unit with the SIACM. The SIACM cannot be
repaired or adjusted and, if damaged or faulty, it
must be replaced.
OPERATION
The microprocessor in the Side Impact Airbag Con-
trol Module (SIACM) contains the side curtain airbag
system logic circuits and controls all of the features
of only the side curtain airbag mounted on the same
side of the vehicle as the SIACM. The SIACM uses
On-Board Diagnostics (OBD) and can communicate
with other electronic modules in the vehicle as well
as with the DRBIIItscan tool using the Programma-
ble Communications Interface (PCI) data bus net-
work. This method of communication is used by the
SIACM to communicate with the Airbag Control
Module (ACM) and for supplemental restraints sys-
tem diagnosis and testing through the 16-way data
link connector located on the driver side lower edge
of the instrument panel. The ACM communicates
with both the left and right SIACM over the PCI
data bus.
The SIACM microprocessor continuously monitors
all of the side curtain airbag electrical circuits to
determine the system readiness. If the SIACM
detects a monitored system fault, it sets an active
and stored Diagnostic Trouble Code (DTC) and sends
electronic messages to the ACM over the PCI data
bus. The ACM will respond by sending an electronic
message to the EMIC to turn on the airbag indicator,
and by storing a DTC that will indicate whether the
left or the right SIACM has stored the DTC that ini-
tiated the airbag indicator illumination. An active
fault only remains for the current ignition switch
cycle, while a stored fault causes a DTC to be stored
in memory by the SIACM. For some DTCs, if a fault
does not recur for a number of ignition cycles, the
SIACM will automatically erase the stored DTC. For
other internal faults, the stored DTC is latched for-
ever.
The SIACM receives battery current on a fused
ignition switch output (run-start) circuit through a
fuse in the Junction Block (JB). The SIACM has a
case ground through its mounting bracket and also
receives a power ground through a ground circuit
and take out of the body wire harness. This take out
has a single eyelet terminal connector that is secured
by a ground screw to the front seat front crossmem-
Fig. 43 Side Impact Airbag Control Module
1 - BRACKET (RIGHT SHOWN)
2 - CONNECTOR RECEPTACLE
3 - SIACM
KJRESTRAINTS 8O - 43
SIDE CURTAIN AIRBAG (Continued)

electronic circuitry of the ITM which includes a
microprocessor, and an ultrasonic receive transducer.
A molded plastic connector receptacle containing six
terminal pins that is soldered to a small circuit board
and extends through a clearance hole in the left front
corner of the ITM housing, and an ultrasonic trans-
mit transducer housing extends from the center of
the right side of the ITM housing. Both the transmit
transducer on the right side of the module and the
receive transducer on the ITM circuit board are
aimed through two small round holes in the sight
shield of the trim cover. The ITM is connected to the
vehicle electrical system by a dedicated take out and
connector of the overhead wire harness that is inte-
gral to the headliner.
The ITM unit cannot be adjusted or repaired and,
if faulty or damaged, it must be replaced. The ITM is
serviced as a unit with the trim cover.
OPERATION
The microprocessor in the Intrusion Transceiver
Module (ITM) contains the motion sensor logic cir-
cuits and controls all of the features of the premium
version of the Vehicle Theft Alarm (VTA). The ITM
uses On-Board Diagnostics (OBD) and can communi-
cate with other electronic modules in the vehicle as
well as with the DRBIIItscan tool using the Pro-
grammable Communications Interface (PCI) data bus
network. This method of communication is used by
the ITM to communicate with the Body Control Mod-
ule (BCM) and for diagnosis and testing through the
16-way data link connector located on the driver side
lower edge of the instrument panel. The ITM also
communicates with the alarm siren over a dedicated
serial bus circuit.
The ITM microprocessor continuously monitors
inputs from its on-board motion sensor circuitry as
well as inputs from the BCM and the alarm siren
module. The on-board ITM motion sensor circuitry
transmits ultrasonic signals into the vehicle cabin
through a transmit transducer, then listens to the
returning signals as the bounce off of objects in the
vehicle interior. If an object is moving in the interior,
a detection circuit in the ITM senses this movement
through the modulation of the returning ultrasonic
signals that occurs due to the Doppler effect. The
motion detect function of the ITM can be disabled by
depressing the ªLockº button on the Remote Keyless
Entry (RKE) transmitter three times within fifteen
seconds, while the security indicator is still flashing
rapidly. The ITM will signal the alarm siren module
to provide a single siren ªchirpº as an audible confir-
mation that the motion sensor function has been dis-
abled.
If movement is detected, the ITM sends an elec-
tronic message to the BCM over the PCI data bus toflash the exterior lighting and sends an electronic
message to the alarm siren module over a dedicated
serial bus line to sound the siren. When the BCM
detects a breach in the perimeter protection through
a door, tailgate, flip-up glass, or hood ajar switch
input, it sends an electronic message to the ITM and
the ITM sends an electronic message to the BCM
over the PCI data bus to flash the exterior lighting
and sends an electronic message to the alarm siren
module over a dedicated serial bus line to sound the
siren. The ITM also monitors inputs from the alarm
siren module for siren battery or siren input/output
circuit tamper alerts, and siren battery condition
alerts, then sets active and stored Diagnostic Trouble
Codes (DTC) for any monitored system faults it
detects. An active fault only remains for the current
ignition switch cycle, while a stored fault causes a
DTC to be stored in memory by the ITM. If a fault
does not recur for fifty ignition cycles, the ITM will
automatically erase the stored DTC.
The ITM is connected to the vehicle electrical sys-
tem through a dedicated take out and connector of
the overhead wire harness. The ITM receives battery
current on a fused B(+) circuit through a fuse in the
Junction Block (JB), and receives ground through a
ground circuit and take out of the body wire harness.
This ground take out has a single eyelet terminal
connector that is secured by a ground screw to the
base of the left D-pillar behind the quarter trim
panel. These connections allow the ITM to remain
operational, regardless of the ignition switch position.
The hard wired inputs and outputs for the ITM may
be diagnosed and tested using conventional diagnos-
tic tools and procedures. However, conventional diag-
nostic methods will not prove conclusive in the
diagnosis of the ITM, the PCI data bus network, or
the electronic message inputs to and outputs from
the ITM. The most reliable, efficient, and accurate
means to diagnose the ITM, the PCI data bus net-
work, and the electronic message inputs to and out-
puts from the ITM requires the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) While pulling downward lightly on either rear
corner of the Intrusion Transceiver Module (ITM)
trim cover, insert a small thin-bladed screwdriver
through each of the service holes on the rear edge of
the trim cover to depress and release the two inte-
gral rear latch features of the module from the
mounting bracket above the headliner (Fig. 11).
(3) Pull the ITM trim cover rearward far enough
to disengage the two integral front latch features of
KJVEHICLE THEFT SECURITY 8Q - 15
INTRUSION TRANSCEIVER MODULE (Continued)

FUEL LEVEL SENDING UNIT /
SENSOR
DESCRIPTION
The fuel gauge sending unit (fuel level sensor) is
attached to the side of the fuel pump module. The
sending unit consists of a float, an arm, and a vari-
able resistor track (card).
OPERATION
The fuel pump module has 4 different circuits
(wires). Two of these circuits are used for the fuel
gauge sending unit for fuel gauge operation, and for
certain OBD II emission requirements. The other 2
wires are used for electric fuel pump operation.
For Fuel Gauge Operation:A constant current
source of approximately 32 milliamps is supplied to
the resistor track on the fuel gauge sending unit.
This is fed directly from the Powertrain Control Mod-
ule (PCM).NOTE: For diagnostic purposes, this
12V power source can only be verified with the
circuit opened (fuel pump module electrical
connector unplugged). With the connectors
plugged, output voltages will vary from about
0.6 volts at FULL, to about 8.6 volts at EMPTY
(about 8.6 volts at EMPTY for Jeep models, and
about 7.0 volts at EMPTY for Dodge Truck mod-
els).The resistor track is used to vary the voltage
(resistance) depending on fuel tank float level. As
fuel level increases, the float and arm move up,
which decreases voltage. As fuel level decreases, the
float and arm move down, which increases voltage.
The varied voltage signal is returned back to the
PCM through the sensor return circuit.
Both of the electrical circuits between the fuel
gauge sending unit and the PCM are hard-wired (not
multi-plexed). After the voltage signal is sent from
the resistor track, and back to the PCM, the PCM
will interpret the resistance (voltage) data and send
a message across the multi-plex bus circuits to the
instrument panel cluster. Here it is translated into
the appropriate fuel gauge level reading. Refer to
Instrument Panel for additional information.
For OBD II Emission Monitor Requirements:
The PCM will monitor the voltage output sent from
the resistor track on the sending unit to indicate fuel
level. The purpose of this feature is to prevent the
OBD II system from recording/setting false misfire
and fuel system monitor diagnostic trouble codes.
The feature is activated if the fuel level in the tank
is less than approximately 15 percent of its rated
capacity. If equipped with a Leak Detection Pump
(EVAP system monitor), this feature will also be acti-
vated if the fuel level in the tank is more than
approximately 85 percent of its rated capacity.
DIAGNOSIS AND TESTING - FUEL LEVEL
SENDING UNIT
The fuel level sending unit contains a variable
resistor (track). As the float moves up or down, elec-
trical resistance will change. Refer to Instrument
Panel and Gauges for Fuel Gauge testing. To test the
gauge sending unit only, it must be removed from
vehicle. The unit is a separate part of the lower fuel
pump module section. Refer to Fuel Pump Module
Removal/Installation for procedures (remove only the
upper section of the fuel pump module). Measure the
resistance across the sending unit terminals. With
float in up position, resistance should be 20 ohms (+/-
5%). With float in down position, resistance should be
270 ohms (+/- 5%).
REMOVAL
The fuel level sending unit (fuel level sensor) and
float assembly is located on the side of the lower sec-
tion of the fuel pump module. The lower section of
the fuel pump module is located within the fuel tank.
(1) Remove lower section of fuel pump module
from fuel tank. Refer to Fuel Pump Module Removal/
Installation.
(2) To remove sending unit from pump module, lift
on plastic locking tab (Fig. 8) while sliding sending
unit upwards.
(3) Disconnect 4±wire electrical connector (Fig. 9)
from bottom of upper section of fuel pump module.
Separate necessary sending unit wiring.
Fig. 8 FUEL LEVEL SENDING UNIT
1 - LIFT TAB HERE FOR REMOVAL
2 - FUEL LEVEL SENDING UNIT
3 - LOWER SECTION OF PUMP MODULE
KJFUEL DELIVERY 14 - 9

(M)Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded
(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.
(G)Generator lamp illuminated
Generic Scan
Tool P-CodeDRB Scan Tool Display Brief Description of DTC
P0545 A/C Clutch Relay Circuit Problem detected in air conditioning clutch relay control
circuit.
P0551 Power Steering Switch Failure Incorrect input state detected for the power steering
switch circuit. PL: High pressure seen at high speed.
P0562 Charging System Voltage Too Low Supply voltage sensed at ECM too low.
P0563 Charging System Voltage Too High Supply voltage sensed at ECM too high.
P0572 Brake Switch Input #1 Signal
Missing
P0573 Brake Switch Input #2 Signal
Missing
P0575 Cruise Control Switch Voltage Low
P0576 Cruise Control Switch Voltage High
P0577 Cruise Control Switch Voltage High
P0600 PCM Failure SPI Communications No communication detected between co-processors in the
control module.
P0601 (M) Internal Controller Failure Internal control module fault condition (check sum)
detected.
P0602 (M) ECM Fueling Calibration Error ECM Internal fault condition detected.
P0604 RAM Check Failure Transmission control module RAM self test fault detected.
-Aisin transmission
P0605 ROM Check Falure Transmission control module ROM self test fault detected
-Aisin transmission
P0606 (M) ECM Failure ECM Internal fault condition detected.
P0615 Starter Relay Control Circuit An open or shorted condition detected in the starter relay
control circuit.
P0622 (G) Generator Field Not Switching
ProperlyAn open or shorted condition detected in the generator
field control circuit.
P0645 A/C Clutch Relay Circuit An open or shorted condition detected in the A/C clutch
relay control circuit.
P0700 EATX Controller DTC Present This SBEC III or JTEC DTC indicates that the EATX or
Aisin controller has an active fault and has illuminated the
MIL via a CCD (EATX) or SCI (Aisin) message. The
specific fault must be acquired from the EATX via CCD or
from the Aisin via ISO-9141.
P0703 Brake Switch Stuck Pressed or
ReleasedIncorrect input state detected in the brake switch circuit.
(Changed from P1595)
P0703 Brake Switch Sense Circuit
P0711 (M) Trans Temp Sensor, No Temp Rise
After StartRelationship between the transmission temperature and
overdrive operation and/or TCC operation indicates a
failure of the Transmission Temperature Sensor. OBD II
Rationality. Was MIL code 37.
P0712 Trans Temp Sensor Voltage Too Low Transmission fluid temperature sensor input below
acceptable voltage. Was MIL code 37.
KJEMISSIONS CONTROL 25 - 9
EMISSIONS CONTROL (Continued)

Normal vehicle miles or engine misfire can cause a
catalyst to decay. This can increase vehicle emissions
and deteriorate engine performance, driveability and
fuel economy.
The catalyst monitor uses dual oxygen sensors
(O2S's) to monitor the efficiency of the converter. The
dual O2S's sensor strategy is based on the fact that
as a catalyst deteriorates, its oxygen storage capacity
and its efficiency are both reduced. By monitoring
the oxygen storage capacity of a catalyst, its effi-
ciency can be indirectly calculated. The upstream
O2S is used to detect the amount of oxygen in the
exhaust gas before the gas enters the catalytic con-
verter. The PCM calculates the A/F mixture from the
output of the O2S. A low voltage indicates high oxy-
gen content (lean mixture). A high voltage indicates a
low content of oxygen (rich mixture).
When the upstream O2S detects a lean condition,
there is an abundance of oxygen in the exhaust gas.
A functioning converter would store this oxygen so it
can use it for the oxidation of HC and CO. As the
converter absorbs the oxygen, there will be a lack of
oxygen downstream of the converter. The output of
the downstream O2S will indicate limited activity in
this condition.
As the converter loses the ability to store oxygen,
the condition can be detected from the behavior of
the downstream O2S. When the efficiency drops, no
chemical reaction takes place. This means the con-
centration of oxygen will be the same downstream as
upstream. The output voltage of the downstream
O2S copies the voltage of the upstream sensor. The
only difference is a time lag (seen by the PCM)
between the switching of the O2S's.
To monitor the system, the number of lean-to-rich
switches of upstream and downstream O2S's is
counted. The ratio of downstream switches to
upstream switches is used to determine whether the
catalyst is operating properly. An effective catalyst
will have fewer downstream switches than it has
upstream switches i.e., a ratio closer to zero. For a
totally ineffective catalyst, this ratio will be one-to-
one, indicating that no oxidation occurs in the device.
The system must be monitored so that when cata-
lyst efficiency deteriorates and exhaust emissions
increase to over the legal limit, the MIL will be illu-
minated.
DESCRIPTION - TRIP DEFINITION
The term ªTripº has different meanings depending
on what the circumstances are. If the MIL (Malfunc-
tion Indicator Lamp) is OFF, a Trip is defined as
when the Oxygen Sensor Monitor and the Catalyst
Monitor have been completed in the same drive cycle.
When any Emission DTC is set, the MIL on the
dash is turned ON. When the MIL is ON, it takes 3good trips to turn the MIL OFF. In this case, it
depends on what type of DTC is set to know what a
ªTripº is.
For the Fuel Monitor or Mis-Fire Monitor (contin-
uous monitor), the vehicle must be operated in the
ªSimilar Condition Windowº for a specified amount of
time to be considered a Good Trip.
If a Non-Contiuous OBDII Monitor fails twice in a
row and turns ON the MIL, re-running that monitor
which previously failed, on the next start-up and
passing the monitor, is considered to be a Good Trip.
These will include the following:
²Oxygen Sensor
²Catalyst Monitor
²Purge Flow Monitor
²Leak Detection Pump Monitor (if equipped)
²EGR Monitor (if equipped)
²Oxygen Sensor Heater Monitor
If any other Emission DTC is set (not an OBDII
Monitor), a Good Trip is considered to be when the
Oxygen Sensor Monitor and Catalyst Monitor have
been completed; or 2 Minutes of engine run time if
the Oxygen Sensor Monitor or Catalyst Monitor have
been stopped from running.
It can take up to 2 Failures in a row to turn on the
MIL. After the MIL is ON, it takes 3 Good Trips to
turn the MIL OFF. After the MIL is OFF, the PCM
will self-erase the DTC after 40 Warm-up cycles. A
Warm-up cycle is counted when the ECT (Engine
Coolant Temperature Sensor) has crossed 160ÉF and
has risen by at least 40ÉF since the engine has been
started.
DESCRIPTION - COMPONENT MONITORS
There are several components that will affect vehi-
cle emissions if they malfunction. If one of these com-
ponents malfunctions the Malfunction Indicator
Lamp (MIL) will illuminate.
Some of the component monitors are checking for
proper operation of the part. Electrically operated
components now have input (rationality) and output
(functionality) checks. Previously, a component like
the Throttle Position sensor (TPS) was checked by
the PCM for an open or shorted circuit. If one of
these conditions occurred, a DTC was set. Now there
is a check to ensure that the component is working.
This is done by watching for a TPS indication of a
greater or lesser throttle opening than MAP and
engine rpm indicate. In the case of the TPS, if engine
vacuum is high and engine rpm is 1600 or greater
and the TPS indicates a large throttle opening, a
DTC will be set. The same applies to low vacuum if
the TPS indicates a small throttle opening.
All open/short circuit checks or any component that
has an associated limp in will set a fault after 1 trip
with the malfunction present. Components without
KJEMISSIONS CONTROL 25 - 19
EMISSIONS CONTROL (Continued)

OPERATION - TASK MANAGER
The Task Manager determines which tests happen
when and which functions occur when. Many of the
diagnostic steps required by OBD II must be per-
formed under specific operating conditions. The Task
Manager software organizes and prioritizes the diag-
nostic procedures. The job of the Task Manager is to
determine if conditions are appropriate for tests to be
run, monitor the parameters for a trip for each test,
and record the results of the test. Following are the
responsibilities of the Task Manager software:
²Test Sequence
²MIL Illumination
²Diagnostic Trouble Codes (DTCs)
²Trip Indicator
²Freeze Frame Data Storage
²Similar Conditions Window
Test Sequence
In many instances, emissions systems must fail
diagnostic tests more than once before the PCM illu-
minates the MIL. These tests are know as 'two trip
monitors.' Other tests that turn the MIL lamp on
after a single failure are known as 'one trip moni-
tors.' A trip is defined as 'start the vehicle and oper-
ate it to meet the criteria necessary to run the given
monitor.'
Many of the diagnostic tests must be performed
under certain operating conditions. However, there
are times when tests cannot be run because another
test is in progress (conflict), another test has failed
(pending) or the Task Manager has set a fault that
may cause a failure of the test (suspend).
²Pending
Under some situations the Task Manager will not
run a monitor if the MIL is illuminated and a fault is
stored from another monitor. In these situations, the
Task Manager postpones monitorspendingresolu-
tion of the original fault. The Task Manager does not
run the test until the problem is remedied.
For example, when the MIL is illuminated for an
Oxygen Sensor fault, the Task Manager does not run
the Catalyst Monitor until the Oxygen Sensor fault is
remedied. Since the Catalyst Monitor is based on sig-
nals from the Oxygen Sensor, running the test would
produce inaccurate results.
²Conflict
There are situations when the Task Manager does
not run a test if another monitor is in progress. In
these situations, the effects of another monitor run-
ning could result in an erroneous failure. If thiscon-
flictis present, the monitor is not run until the
conflicting condition passes. Most likely the monitor
will run later after the conflicting monitor has
passed.For example, if the Fuel System Monitor is in
progress, the Task Manager does not run the EGR
Monitor. Since both tests monitor changes in air/fuel
ratio and adaptive fuel compensation, the monitors
will conflict with each other.
²Suspend
Occasionally the Task Manager may not allow a two
trip fault to mature. The Task Manager willsus-
pendthe maturing of a fault if a condition exists
that may induce an erroneous failure. This prevents
illuminating the MIL for the wrong fault and allows
more precis diagnosis.
For example, if the PCM is storing a one trip fault
for the Oxygen Sensor and the EGR monitor, the
Task Manager may still run the EGR Monitor but
will suspend the results until the Oxygen Sensor
Monitor either passes or fails. At that point the Task
Manager can determine if the EGR system is actu-
ally failing or if an Oxygen Sensor is failing.MIL Illumination
The PCM Task Manager carries out the illumina-
tion of the MIL. The Task Manager triggers MIL illu-
mination upon test failure, depending on monitor
failure criteria.
The Task Manager Screen shows both a Requested
MIL state and an Actual MIL state. When the MIL is
illuminated upon completion of a test for a third trip,
the Requested MIL state changes to OFF. However,
the MIL remains illuminated until the next key
cycle. (On some vehicles, the MIL will actually turn
OFF during the third key cycle) During the key cycle
for the third good trip, the Requested MIL state is
OFF, while the Actual MIL state is ON. After the
next key cycle, the MIL is not illuminated and both
MIL states read OFF.
Diagnostic Trouble Codes (DTCs)
With OBD II, different DTC faults have different
priorities according to regulations. As a result, the
priorities determine MIL illumination and DTC era-
sure. DTCs are entered according to individual prior-
ity. DTCs with a higher priority overwrite lower
priority DTCs.
Priorities
²Priority 0 ÐNon-emissions related trouble codes
²Priority 1 Ð One trip failure of a two trip fault
for non-fuel system and non-misfire.
²Priority 2 Ð One trip failure of a two trip fault
for fuel system (rich/lean) or misfire.
²Priority3ÐTwotrip failure for a non-fuel sys-
tem and non-misfire or matured one trip comprehen-
sive component fault.
KJEMISSIONS CONTROL 25 - 21
EMISSIONS CONTROL (Continued)

²Priority4ÐTwotrip failure or matured fault
for fuel system (rich/lean) and misfire or one trip cat-
alyst damaging misfire.
Non-emissions related failures have no priority.
One trip failures of two trip faults have low priority.
Two trip failures or matured faults have higher pri-
ority. One and two trip failures of fuel system and
misfire monitor take precedence over non-fuel system
and non-misfire failures.
DTC Self Erasure
With one trip components or systems, the MIL is
illuminated upon test failure and DTCs are stored.
Two trip monitors are components requiring failure
in two consecutive trips for MIL illumination. Upon
failure of the first test, the Task Manager enters a
maturing code. If the component fails the test for a
second time the code matures and a DTC is set.
After three good trips the MIL is extinguished and
the Task Manager automatically switches the trip
counter to a warm-up cycle counter. DTCs are auto-
matically erased following 40 warm-up cycles if the
component does not fail again.
For misfire and fuel system monitors, the compo-
nent must pass the test under a Similar Conditions
Window in order to record a good trip. A Similar Con-
ditions Window is when engine RPM is within  375
RPM and load is within  10% of when the fault
occurred.
NOTE: It is important to understand that a compo-
nent does not have to fail under a similar window of
operation to mature. It must pass the test under a
Similar Conditions Window when it failed to record
a Good Trip for DTC erasure for misfire and fuel
system monitors.
DTCs can be erased anytime with a DRB III. Eras-
ing the DTC with the DRB III erases all OBD II
information. The DRB III automatically displays a
warning that erasing the DTC will also erase all
OBD II monitor data. This includes all counter infor-
mation for warm-up cycles, trips and Freeze Frame.
Trip Indicator
TheTripis essential for running monitors and
extinguishing the MIL. In OBD II terms, a trip is a
set of vehicle operating conditions that must be met
for a specific monitor to run. All trips begin with a
key cycle.
Good Trip
The Good Trip counters are as follows:
²Specific Good Trip
²Fuel System Good Trip
²Misfire Good Trip
²Alternate Good Trip (appears as a Global Good
Trip on DRB III)²Comprehensive Components
²Major Monitor
²Warm-Up Cycles
Specific Good Trip
The term Good Trip has different meanings
depending on the circumstances:
²If the MIL is OFF, a trip is defined as when the
Oxygen Sensor Monitor and the Catalyst Monitor
have been completed in the same drive cycle.
²If the MIL is ON and a DTC was set by the Fuel
Monitor or Misfire Monitor (both continuous moni-
tors), the vehicle must be operated in the Similar
Condition Window for a specified amount of time.
²If the MIL is ON and a DTC was set by a Task
Manager commanded once-per-trip monitor (such as
the Oxygen Sensor Monitor, Catalyst Monitor, Purge
Flow Monitor, Leak Detection Pump Monitor, EGR
Monitor or Oxygen Sensor Heater Monitor), a good
trip is when the monitor is passed on the next start-
up.
²If the MIL is ON and any other emissions DTC
was set (not an OBD II monitor), a good trip occurs
when the Oxygen Sensor Monitor and Catalyst Mon-
itor have been completed, or two minutes of engine
run time if the Oxygen Sensor Monitor and Catalyst
Monitor have been stopped from running.
Fuel System Good Trip
To count a good trip (three required) and turn off
the MIL, the following conditions must occur:
²Engine in closed loop
²Operating in Similar Conditions Window
²Short Term multiplied by Long Term less than
threshold
²Less than threshold for a predetermined time
If all of the previous criteria are met, the PCM will
count a good trip (three required) and turn off the
MIL.
Misfire Good Trip
If the following conditions are met the PCM will
count one good trip (three required) in order to turn
off the MIL:
²Operating in Similar Condition Window
²1000 engine revolutions with no misfire
Warm-Up Cycles
Once the MIL has been extinguished by the Good
Trip Counter, the PCM automatically switches to a
Warm-Up Cycle Counter that can be viewed on the
DRB III. Warm-Up Cycles are used to erase DTCs
and Freeze Frames. Forty Warm-Up cycles must
occur in order for the PCM to self-erase a DTC and
Freeze Frame. A Warm-Up Cycle is defined as fol-
lows:
²Engine coolant temperature must start below
and rise above 160É F
²Engine coolant temperature must rise by 40É F
²No further faults occur
25 - 22 EMISSIONS CONTROLKJ
EMISSIONS CONTROL (Continued)

EVAPORATIVE EMISSIONS
TABLE OF CONTENTS
page page
EVAPORATIVE EMISSIONS
DESCRIPTION - EVAPORATION CONTROL
SYSTEM............................24
SPECIFICATIONS
TORQUE............................26
EVAP/PURGE SOLENOID
DESCRIPTION.........................27
OPERATION...........................27
REMOVAL.............................27
INSTALLATION.........................27
FUEL FILLER CAP
DESCRIPTION.........................27
OPERATION...........................27
LEAK DETECTION PUMP
DESCRIPTION.........................27
OPERATION...........................28
REMOVAL.............................28INSTALLATION.........................28
ORVR
DESCRIPTION.........................29
OPERATION...........................29
P C V VA LV E
DESCRIPTION.........................29
OPERATION...........................31
DIAGNOSIS AND TESTING - PCV VALVE.....31
REMOVAL.............................32
INSTALLATION.........................32
VACUUM LINES
DESCRIPTION.........................33
VAPOR CANISTER
DESCRIPTION.........................33
OPERATION...........................33
REMOVAL.............................33
INSTALLATION.........................33
EVAPORATIVE EMISSIONS
DESCRIPTION - EVAPORATION CONTROL
SYSTEM
The evaporation control system prevents the emis-
sion of fuel tank vapors into the atmosphere. When
fuel evaporates in the fuel tank, the vapors pass
through the control valve located in the top section of
the fuel pump module, through the fuel management
valve, and through vent hoses and tubes to a char-
coal filled evaporative canister. The canister tempo-
rarily holds the vapors. The Powertrain Control
Module (PCM) allows intake manifold vacuum to
draw vapors into the combustion chambers during
certain operating conditions.
Gas powered engines use a duty cycle purge sys-
tem. The PCM controls vapor flow by operating theduty cycle EVAP purge solenoid. Refer to Duty Cycle
EVAP Canister Purge Solenoid.
When equipped with certain emissions packages, a
Leak Detection Pump (LDP) will be used as part of
the evaporative system for OBD II requirements.
Also refer to Leak Detection Pump.
Vehicles powered with gasoline engines are also
equipped with ORVR (On-Board Refueling Vapor
Recovery). Refer to ORVR for additional information.
NOTE: The evaporative system uses specially man-
ufactured lines/hoses. If replacement becomes nec-
essary, only use fuel resistant, low permeation
hose.
Certain components can be found in (Fig. 1).
25 - 24 EVAPORATIVE EMISSIONSKJ

COVER - REMOVAL, COWL TRIM.......23-157
COVER - REMOVAL, INSTRUMENT
PANEL TOP........................23-152
COVER - REMOVAL, STRUCTURAL........9-55
COVER(S) - DESCRIPTION, CYLINDER
HEAD...............................9-25
COVER(S) - INSTALLATION, CYLINDER
HEAD...........................9-26,9-34
COVER(S) - INSTALLATION, TIMING
BELT / CHAIN........................9-76
COVER(S) - REMOVAL, CYLINDER HEAD . . 9-25,
9-34
COVER(S) - REMOVAL, TIMING BELT /
CHAIN..............................9-74
COWL GRILLE - INSTALLATION........23-140
COWL GRILLE - REMOVAL............23-140
COWL TRIM COVER - INSTALLATION....23-157
COWL TRIM COVER - REMOVAL.......23-157
COWL WEATHERSTRIP - INSTALLATION . 23-185
COWL WEATHERSTRIP - REMOVAL.....23-185
COWL/PLENUM SEAL - INSTALLATION . . . 23-187
COWL/PLENUM SEAL - REMOVAL......23-187
COWL/PLENUM WINDOW BAFFLE SEAL -
INSTALLATION......................23-187
COWL/PLENUM WINDOW BAFFLE SEAL -
REMOVAL.........................23-187
CRADLE CROSSMEMBER -
INSTALLATION, ENGINE................13-6
CRADLE CROSSMEMBER - REMOVAL,
ENGINE.............................13-6
CRANKSHAFT - DESCRIPTION...........9-42
CRANKSHAFT - INSPECTION.............9-43
CRANKSHAFT - INSTALLATION...........9-43
CRANKSHAFT - REMOVAL..............9-43
CRANKSHAFT OIL SEAL - FRONT -
INSTALLATION........................9-47
CRANKSHAFT OIL SEAL - FRONT -
REMOVAL...........................9-46
CRANKSHAFT OIL SEAL - REAR -
INSTALLATION........................9-48
CRANKSHAFT OIL SEAL - REAR -
REMOVAL...........................9-48
CRANKSHAFT POSITION SENSOR -
DESCRIPTION.......................14-30
CRANKSHAFT POSITION SENSOR -
INSTALLATION.......................14-32
CRANKSHAFT POSITION SENSOR -
OPERATION.........................14-31
CRANKSHAFT POSITION SENSOR -
REMOVAL..........................14-31
CROSSMEMBER - INSTALLATION,
ENGINE CRADLE......................13-6
CROSSMEMBER - INSTALLATION,
RADIATOR.........................23-146
CROSSMEMBER - INSTALLATION, REAR . . . 13-7
CROSSMEMBER - REMOVAL, ENGINE
CRADLE.............................13-6
CROSSMEMBER - REMOVAL, RADIATOR . 23-146
CROSSMEMBER - REMOVAL, REAR.......13-7
CROSS-OVER PIPE - INSTALLATION.......11-3
CROSS-OVER PIPE - REMOVAL..........11-3
CRUISE INDICATOR - DESCRIPTION......8J-16
CRUISE INDICATOR - OPERATION.......8J-17
CURTAIN AIRBAG - DESCRIPTION, SIDE . . 8O-38
CURTAIN AIRBAG - INSTALLATION, SIDE . . 8O-41
CURTAIN AIRBAG - OPERATION, SIDE....8O-39
CURTAIN AIRBAG - REMOVAL, SIDE.....8O-40
CUSHION - FRONT - INSTALLATION,
SEAT .............................23-167
CUSHION - FRONT - INSTALLATION,
SEAT BACK........................23-167
CUSHION - FRONT - REMOVAL, SEAT . . . 23-167
CUSHION - FRONT - REMOVAL, SEAT
BACK.............................23-167
CUSHION - REAR - INSTALLATION, SEAT . 23-171
CUSHION - REAR - INSTALLATION, SEAT
BACK.............................23-170
CUSHION - REAR - REMOVAL, SEAT....23-171
CUSHION - REAR - REMOVAL, SEAT
BACK
.............................23-170
CUSHION COVER - FRONT -
INSTALLATION, SEAT
.................23-167
CUSHION COVER - FRONT - REMOVAL,
SEAT
.............................23-167
CUSHION SIDE SHIELDS -
INSTALLATION, SEAT
.................23-167
CUSHION SIDE SHIELDS - REMOVAL,
SEAT
.............................23-167CUSTOMER PREFERENCES - STANDARD
PROCEDURE, RKE TRANSMITTER........8N-8
CV JOINT/BOOT-INNER - INSTALLATION . . . 3-17
CV JOINT/BOOT-INNER - REMOVAL.......3-15
CV JOINT/BOOT-OUTER - INSTALLATION . . . 3-13
CV JOINT/BOOT-OUTER - REMOVAL.......3-12
CYLINDER - DESCRIPTION, MASTER......5-24
CYLINDER - INSPECTION, MASTER........6-9
CYLINDER - INSTALLATION, FLIP-UP
GLASS SUPPORT...................23-139
CYLINDER - INSTALLATION, LOCK......23-125,
23-138
CYLINDER - INSTALLATION, LOCK.......19-11
CYLINDER - INSTALLATION, MASTER.....5-25
CYLINDER - INSTALLATION, SUPPORT . . . 23-120
CYLINDER - OPERATION, MASTER........5-24
CYLINDER - REMOVAL, FLIP-UP GLASS
SUPPORT.........................23-139
CYLINDER - REMOVAL, LOCK....23-125,23-137
CYLINDER - REMOVAL, LOCK...........19-10
CYLINDER - REMOVAL, MASTER.........5-25
CYLINDER - REMOVAL, SUPPORT......23-120
CYLINDER BLEEDING - STANDARD
PROCEDURE, MASTER.................5-24
CYLINDER BORE HONING - STANDARD
PROCEDURE.........................9-39
CYLINDER COMBUSTION PRESSURE
LEAKAGE - DIAGNOSIS AND TESTING......9-8
CYLINDER COMPRESSION PRESSURE -
DIAGNOSIS AND TESTING...............9-8
CYLINDER FLUID LEVEL - STANDARD
PROCEDURES, MASTER................5-26
CYLINDER HEAD - DESCRIPTION.........9-30
CYLINDER HEAD COVER(S) -
DESCRIPTION........................9-25
CYLINDER HEAD COVER(S) -
INSTALLATION....................9-26,9-34
CYLINDER HEAD COVER(S) - REMOVAL . . . 9-25,
9-34
CYLINDER HEAD GASKET - DIAGNOSIS
AND TESTING....................9-19,9-30
CYLINDER LOCK SWITCH -
DESCRIPTION, DOOR..................8Q-9
CYLINDER LOCK SWITCH -
DESCRIPTION, TAILGATE...............8N-9
CYLINDER LOCK SWITCH - DIAGNOSIS
AND TESTING, DOOR.................8Q-10
CYLINDER LOCK SWITCH - DIAGNOSIS
AND TESTING, TAILGATE...............8N-9
CYLINDER LOCK SWITCH -
INSTALLATION, DOOR.................8Q-10
CYLINDER LOCK SWITCH -
INSTALLATION, TAILGATE..............8N-10
CYLINDER LOCK SWITCH - OPERATION,
DOOR.............................8Q-10
CYLINDER LOCK SWITCH - OPERATION,
TAILGATE...........................8N-9
CYLINDER LOCK SWITCH - REMOVAL,
DOOR.............................8Q-10
CYLINDER LOCK SWITCH - REMOVAL,
TAILGATE..........................8N-10
CYLINDER/POWER BOOSTER -
DIAGNOSIS AND TESTING, MASTER . . 5-21,5-24
CYLINDERS - ASSEMBLY, WHEEL.........5-29
CYLINDERS - CLEANING, WHEEL.........5-28
CYLINDERS - DISASSEMBLY, WHEEL......5-28
CYLINDERS - INSPECTION, WHEEL.......5-29
CYLINDERS - INSTALLATION, WHEEL
.....5-29
CYLINDERS - REMOVAL, WHEEL
.........5-28
DAMAGED OR WORN THREADS -
STANDARD PROCEDURE, REPAIR
.........9-9
DAMPER - INSTALLATION, VIBRATION
.....9-55
DAMPER - REMOVAL, VIBRATION
........9-54
DATA LINK CONNECTOR - DESCRIPTION
. . 8E-10
DATA LINK CONNECTOR - OPERATION
....8E-10
DAYTIME RUNNING LAMP RELAY -
DESCRIPTION
.......................8L-20
DAYTIME RUNNING LAMP RELAY -
INSTALLATION
.......................8L-21
DAYTIME RUNNING LAMP RELAY -
OPERATION
.........................8L-20
DAYTIME RUNNING LAMP RELAY -
REMOVAL
..........................8L-21
DECOUPLER - DIAGNOSIS AND
TESTING, GENERATOR
................8F-27
DECOUPLER PULLEY - DESCRIPTION,
GENERATOR
........................8F-26DECOUPLER PULLEY - INSTALLATION,
GENERATOR........................8F-30
DECOUPLER PULLEY - OPERATION,
GENERATOR........................8F-27
DECOUPLER PULLEY - REMOVAL,
GENERATOR........................8F-27
DEFINITION - DESCRIPTION, TRIP.......25-19
DEFLECTOR - INSTALLATION, WIND.....23-180
DEFLECTOR - REMOVAL, WIND........23-180
DEFOGGER - DESCRIPTION, REAR
WINDOW............................8G-3
DEFOGGER - OPERATION, REAR
WINDOW............................8G-3
DEFOGGER FUNCTION - DIAGNOSIS AND
TESTING, REAR HVAC CONTROL
ASSEMBLY WINDOW..................8G-9
DEFOGGER GRID - DESCRIPTION, REAR
WINDOW............................8G-5
DEFOGGER GRID - DIAGNOSIS AND
TESTING, REAR WINDOW..............8G-5
DEFOGGER GRID - OPERATION, REAR
WINDOW............................8G-5
DEFOGGER RELAY - DESCRIPTION,
REAR WINDOW.......................8G-6
DEFOGGER RELAY - DIAGNOSIS AND
TESTING, REAR WINDOW..............8G-6
DEFOGGER RELAY - INSTALLATION,
REAR WINDOW.......................8G-7
DEFOGGER RELAY - OPERATION, REAR
WINDOW............................8G-6
DEFOGGER RELAY - REMOVAL, REAR
WINDOW............................8G-7
DEFOGGER SWITCH - DESCRIPTION,
REAR WINDOW.......................8G-8
DEFOGGER SWITCH - DIAGNOSIS AND
TESTING, REAR WINDOW..............8G-8
DEFOGGER SWITCH - OPERATION, REAR
WINDOW............................8G-8
DEFOGGER SYSTEM - DIAGNOSIS AND
TESTING, REAR WINDOW..............8G-4
DEFROST DOO - INSTALLATION, FLOOR . . 24-37
DEFROST DOOR - REMOVAL...........24-35
DEFROST DOOR - REMOVAL, FLOOR.....24-36
DEFROST DOOR ACTUATOR -
INSTALLATION, FLOOR................24-25
DEFROST DOOR ACTUATOR - REMOVAL,
FLOOR.............................24-24
DEFROST DUCT/DEMISTER ADAPTOR -
REMOVAL..........................24-32
DEFROST/DEMISTER DUCT -
INSTALLATION.......................24-32
DELIVERY - DESCRIPTION, FUEL.........14-2
DELIVERY - OPERATION, FUEL...........14-3
DEMAGNETIZING - STANDARD
PROCEDURE, COMPASS...............8M-2
DEMISTER OUTLETS - DESCRIPTION.....24-29
DEPLOYMENT - STANDARD
PROCEDURE, SERVICE AFTER A
SUPPLEMENTAL RESTRAINT............8O-6
DETECTION PUMP - DESCRIPTION, LEAK . 25-27
DETECTION PUMP - INSTALLATION,
LEAK..............................25-28
DETECTION PUMP - OPERATION, LEAK . . . 25-28
DETECTION PUMP - REMOVAL, LEAK....25-28
DEVICES - STANDARD PROCEDURE,
ELECTROSTATIC DISCHARGE (ESD)
SENSITIVE........................8W-01-8
DIAGNOSIS CHART - DIAGNOSIS AND
TESTING, COOLING SYSTEM.............7-6
DIAGNOSIS, DIAGNOSIS AND TESTING -
WATER DRAINAGE AND WIND NOISE . . . 23-176
DIAGNOSTIC PROCEDURES, DIAGNOSIS
AND TESTING......................23-176
DIAGNOSTIC TROUBLE CODES -
DESCRIPTION........................25-2
DIAGNOSTICS (OBD) - DIAGNOSIS AND
TESTING, ON-BOARD...................7-3
DIAGRAMS - DESCRIPTION, HOW TO
USE WIRING......................8W-01-1
DIAGRAMS - HYDRAULIC SCHEMATICS,
SCHEMATICS.......................21-100
DIESEL - TORQUE, EXCEPT.............8F-23
DIFFERENTIAL - ASSEMBLY
........3-105,3-41
DIFFERENTIAL - DISASSEMBLY
.....3-105,3-41
DIFFERENTIAL - INSTALLATION
. 3-105,3-42,3-73
DIFFERENTIAL - REMOVAL
.....3-104,3-40,3-71
DIFFERENTIAL - TRAC-LOK - ASSEMBLY
. . 3-109,
3-77
KJINDEX 7
Description Group-Page Description Group-Page Description Group-Page