ECU DODGE RAM 1500 1998 2.G Workshop Manual

HEATER INLET HOSE
REMOVAL
The heater inlet hose is constructed from rubber
hoses and plastic hose connectors. The ends are
secured to the heater core, engine and engine coolant
reservoir (depending on engine application) by spring
tension clamps.
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
WARNING) and (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING - CAUTION).
(1) Drain the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOLING
SYSTEM DRAIN).
(2) Remove the heater hose retaining brackets as
required (depending on engine application).
(3) Using spring tension clamp pliers, compress
and slide the clamps off of each end of the hose being
removed (Fig. 24).
CAUTION: DO NOT apply excessive pressure on
heater tubes or connections when removing heater
hoses. Excessive pressure may damage or deform
the tubes/heater core, causing an engine coolant
leak.
(4) Disconnect each hose end by carefully twisting
the hose back and forth on the tube, while gently
pulling it away from the end of the tube.
(5) If necessary, carefully cut the hose end and
peel the hose off of the tube.
NOTE: Replacement of the heater inlet hose will be
required if the hose ends are cut for removal.
(6) Remove the heater inlet hose from the engine
compartment.
(7) Separate the heater hoses from each other as
required (depending on engine application).
INSTALLATION
(1) If separated, reconnect the heater hoses to each
other as required (depending on engine application).
(2) Position the heater inlet hose into the engine
compartment.
(3) Using spring tension clamp pliers, compress
and slide each clamp away from the end of the hose
being installed.
(4) Install each hose by carefully twisting the hose
back and forth while gently pushing it onto the tube
end.(5) Using spring tension clamp pliers, compress
and slide the clamps onto each end of the hose being
installed.
(6) Install the heater hose retaining brackets as
required (depending on engine application).
(7) Refill the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOLING
SYSTEM REFILL).
HEATER RETURN HOSE
REMOVAL
The heater return hose is constructed from rubber
hoses and plastic hose connectors. The ends are
secured to the heater core, engine and engine coolant
reservoir (depending on engine application) by spring
tension clamps.
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
WARNING) and (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING - CAUTION).
Fig. 24 Heater Hoses - Typical
1 - HEATER CORE TUBES
2 - HEATER INLET HOSE
3 - RETAINING BRACKET
4 - HOSE CONNECTOR
5 - SPRING CLAMP
6 - HEATER RETURN HOSE
24 - 64 PLUMBINGDR

ING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT RECOVERY).
(5) Remove the plastic cover from the condenser
outlet stud.
(6) Remove the nut that secures the liquid line fit-
ting to the condenser outlet (Fig. 26).
(7) Disconnect the liquid line from the condenser.
(8) Remove the seal from the liquid line fitting and
discard.
(9) Install plugs in, or tape over the liquid line fit-
ting and condenser outlet port.
(10) Disengage the liquid lines from the body
retaining clips.
(11) Remove the secondary retaining clip from the
spring-lock coupler that secures the front section of
the liquid line to the rear section of the liquid line.
(12) Using the proper A/C line disconnect tool, dis-
connect the front section of the liquid line from the
rear section of the liquid line (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING/REFRIG-
ERANT LINE COUPLER - REMOVAL).
(13) Remove the O-ring seal from the liquid line
fitting and discard.
(14) Install plugs in, or tape over the opened front
liquid line fitting and rear liquid line tube.
(15) Remove the secondary retaining clip from the
spring-lock coupler that secures the liquid line to the
evaporator inlet tube.
(16) Using the proper A/C line disconnect tool, dis-
connect the liquid line from the evaporator inlet tube
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING/REFRIGERANT LINE COUPLER -
REMOVAL).
(17) Remove the O-ring seal from the liquid line
fitting and discard.
(18) Install plugs in, or tape over the opened liquid
line fitting and evaporator inlet tube.
(19) Remove both sections of the liquid line from
the engine compartment.
INSTALLATION
(1) Position both sections of the liquid line into the
engine compartment.
(2) Remove the tape or plugs from the rear liquid
line fitting and the evaporator inlet tube.
(3) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the rear liquid line
fitting. Use only the specified O-ring as it is made of
a special material for the R-134a system. Use only
refrigerant oil of the type recommended for the A/C
compressor in the vehicle.
(4) Connect the liquid line fitting to the evaporator
inlet tube (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING/REFRIGERANT LINE COU-
PLER - INSTALLATION).(5) Install the secondary retaining clip onto the
spring-lock coupler that secures the liquid line fitting
to the evaporator inlet tube.
(6) Remove the tape or plugs from the front liquid
line fitting and the rear liquid line tube.
(7) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the front liquid line
fitting. Use only the specified O-ring as it is made of
a special material for the R-134a system. Use only
refrigerant oil of the type recommended for the A/C
compressor in the vehicle.
(8) Connect the front liquid line fitting to the rear
liquid line tube (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING/REFRIGERANT LINE
COUPLER - INSTALLATION).
(9) Install the secondary retaining clip onto the
spring-lock coupler that secures the front liquid line
fitting to the rear liquid line tube.
(10) Engage the liquid lines to the body retaining
clips.
(11) Remove the tape or plugs from the liquid line
fitting and condenser outlet port.
(12) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the liquid line fitting.
Use only the specified O-ring as it is made of a spe-
Fig. 26 A/C Liquid Line - Typical
1 - BODY RETAINING CLIP
2 - SECONDARY RETAINING CLIP
3 - BODY RETAINING CLIP
4 - LIQUID LINE (REAR SECTION)
5 - SECONDARY RETAINING CLIP
6 - EVAPORATOR INLET TUBE
7 - A/C CONDENSER
8 - NUT
9 - BODY RETAINING CLIP
10 - LIQUID LINE (FRONT SECTION)
24 - 66 PLUMBINGDR
LIQUID LINE (Continued)

cial material for the R-134a system. Use only refrig-
erant oil of the type recommended for the A/C
compressor in the vehicle.
(13) Connect the liquid line to the condenser outlet
port.
(14) Install and tighten the nut that secures the
liquid line fitting to the condenser. Tighten the nut to
20 N´m (180 in. lbs.).
(15) Install the plastic cover onto the condenser
outlet stud.
(16) If equipped with the diesel engine, install the
passenger side battery tray (Refer to 8 - ELECTRI-
CAL/BATTERY SYSTEM/TRAY - INSTALLATION).
(17) If equipped with the diesel engine, install the
passenger side battery (Refer to 8 - ELECTRICAL/
BATTERY SYSTEM/BATTERY - INSTALLATION).
(18) Reconnect the battery negative cables.
(19) Evacuate the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE).
(20) Charge the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE).
REFRIGERANT
DESCRIPTION
The refrigerant used in this air conditioning sys-
tem is a HydroFluoroCarbon (HFC), type R-134a.
Unlike R-12, which is a ChloroFluoroCarbon (CFC),
R-134a refrigerant does not contain ozone-depleting
chlorine. R-134a refrigerant is a non-toxic, non-flam-
mable, clear, and colorless liquefied gas.
Even though R-134a does not contain chlorine, it
must be reclaimed and recycled just like CFC-type
refrigerants. This is because R-134a is a greenhouse
gas and can contribute to global warming.
OPERATION
R-134a refrigerant is not compatible with R-12
refrigerant in an air conditioning system. Even a
small amount of R-12 added to an R-134a refrigerant
system will cause compressor failure, refrigerant oil
sludge or poor air conditioning system performance.
In addition, the PolyAlkylene Glycol (PAG) synthetic
refrigerant oils used in an R-134a refrigerant system
are not compatible with the mineral-based refriger-
ant oils used in an R-12 refrigerant system.
R-134a refrigerant system service ports, service
tool couplers and refrigerant dispensing bottles have
all been designed with unique fittings to ensure that
an R-134a system is not accidentally contaminated
with the wrong refrigerant (R-12). There are alsolabels posted in the engine compartment of the vehi-
cle and on the compressor identifying to service tech-
nicians that the air conditioning system is equipped
with R-134a.
REFRIGERANT LINE COUPLER
DESCRIPTION
Spring-lock type refrigerant line couplers are used
to connect some of the refrigerant lines and other
components to the refrigerant system. These couplers
require a special tool for disengaging the two coupler
halves.
OPERATION
The spring-lock coupler is held together by a garter
spring inside a circular cage on the male half of the
fitting (Fig. 27). When the two coupler halves are
connected, the flared end of the female fitting slips
behind the garter spring inside the cage on the male
fitting. The garter spring and cage prevent the flared
end of the female fitting from pulling out of the cage.
Two O-rings on the male half of the fitting are
used to seal the connection. These O-rings are com-
patible with R-134a refrigerant and must be replaced
with O-rings made of the same material.
Secondary clips are installed over the two con-
nected coupler halves at the factory for added protec-
tion. In addition, some models have a plastic ring
that is used at the factory as a visual indicator to
confirm that these couplers are connected. After the
Fig. 27 Spring-Lock Coupler - Typical
1 - MALE HALF SPRING-LOCK COUPLER
2 - FEMALE HALF SPRING-LOCK COUPLER
3 - SECONDARY CLIP
4 - CONNECTION INDICATOR RING
5 - COUPLER CAGE
6 - GARTER SPRING
7 - COUPLER CAGE
8 - O-RING SEALS
DRPLUMBING 24 - 67
LIQUID LINE (Continued)

(1) Disconnect and isolate the battery negative
cable.
(2) Recover the refrigerant from the refrigerant
system (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT RECOVERY).
(3) Disconnect the wire harness connector from the
A/C pressure transducer.
(4) Remove the nut that secures the discharge line
fitting to the condenser inlet port (Fig. 29).
(5) Disconnect the discharge line from the con-
denser.
(6) Remove the O-ring seal from the discharge line
fitting and discard.
(7) Install plugs in, or tape over the discharge line
fitting and condenser inlet port.
(8) Remove the bolt that secures the suction/dis-
charge line assembly to the A/C compressor.
(9) Disconnect the suction/discharge line assembly
from the A/C compressor.
(10) Remove the O-ring seals from the suction and
discharge line fittings and discard.
(11) Install plugs in, or tape over all of the opened
refrigerant line fittings and the compressor ports.(12) Remove the secondary retaining clip from the
spring-lock coupler that secures the suction line to
the accumulator outlet tube (Fig. 30).
(13) Using the proper A/C line disconnect tool, dis-
connect the suction line from the accumulator outlet
tube (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING/REFRIGERANT LINE COUPLER -
REMOVAL).
(14) Remove the O-ring seal from the accumulator
outlet tube fitting and discard.
(15) Install plugs in, or tape over the opened suc-
tion line and the accumulator outlet tube fitting.
(16) Remove the suction/discharge line assembly
from the engine compartment.
(17) If necessary, remove the A/C pressure trans-
ducer from the discharge line.
REMOVAL - 3.7L/4.7L AND 5.7L HEMI ENGINE
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
WARNING) and (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING - CAUTION).
Fig. 29 A/C Suction Line - 5.9L Diesel Engine
1 - CONDENSER
2 - NUT
3 - LIQUID LINE
4 - NUT
5 - PRESSURE TRANSDUCER WIRE CONNECTOR
6 - A/C COMPRESSOR
7 - BOLT
8 - SUCTION/DISCHARGE LINE ASSEMBLY
Fig. 30 Suction Line - A/C Accumulator
1 - RH INNER FENDER
2 - ACCUMULATOR INLET TUBE
3 - A/C LINE SECONDARY RETAINING CLIP
4 - EVAPORATOR OUTLET TUBE
5 - BOLTS (2)
6 - ACCUMULATOR
7 - SUCTION LINE
8 - A/C LOW PRESSURE SERVICE PORT
9 - A/C LINE SECONDARY RETAINING CLIP
DRPLUMBING 24 - 71
SUCTION LINE (Continued)

(1) Disconnect and isolate the battery negative
cable.
(2) Recover the refrigerant from the refrigerant
system (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT RECOVERY).
(3) Remove the nut that secures the suction line
fitting to the compressor inlet port (Fig. 31) or (Fig.
32), depending on application.
(4) Disconnect the suction line from the compres-
sor.
(5) Remove the O-ring seal from the suction line
fitting and discard.
(6) Install plugs in, or tape over the suction line
fitting and compressor inlet port.
(7) Remove the secondary retaining clip from the
spring-lock coupler that secures the suction line to
the accumulator outlet tube (Fig. 33).
(8) Using the proper A/C line disconnect tool, dis-
connect the suction line from the accumulator outlet
tube (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING/REFRIGERANT LINE COUPLER -
REMOVAL).
(9) Remove the O-ring seal from the accumulator
outlet tube fitting and discard.(10) Install plugs in, or tape over the opened suc-
tion line and the accumulator outlet tube fitting.
INSTALLATION
INSTALLATION - 5.9L DIESEL ENGINE
(1) If removed, install the A/C pressure transducer
onto the discharge line using a new O-ring seal.
Tighten the transducer securely.
(2) Position the suction/discharge line assembly
into the engine compartment.
(3) Remove the tape or plugs from the suction line
and the accumulator outlet tube fitting.
(4) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the accumulator out-
let tube fitting. Use only the specified O-ring as it is
made of a special material for the R-134a system.
Use only refrigerant oil of the type recommended for
the A/C compressor in the vehicle.
(5) Connect the suction line to the accumulator
outlet tube (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING/REFRIGERANT LINE COU-
PLER - INSTALLATION).
(6) Install the secondary retaining clip onto the
spring-lock coupler that secures the suction line to
the accumulator outlet tube.Fig. 31 A/C Discharge Line - 3.7L Shown, 4.7L
Typical
1 - NUT
2 - FRONT UPPER CROSSMEMBER
3 - A/C CONDENSER
4 - NUT (2)
5 - SUCTION LINE
6 - A/C COMPRESSOR
7 - A/C PRESSURE TRANSDUCER
8 - WIRE HARNESS CONNECTOR
9 - A/C DISCHARGE LINE
Fig. 32 A/C Suction Line - 5.7L Hemi Engine
1 - DISCHARGE LINE
2 - NUT
3 - CONDENSER
4 - NUT
5 - SUCTION LINE
6 - A/C COMPRESSOR
7 - NUT
8 - A/C PRESSURE TRANSDUCER
24 - 72 PLUMBINGDR
SUCTION LINE (Continued)

(7) Remove the tape or plugs from the suction and
discharge line fittings and the compressor ports.
(8) Lubricate new rubber O-ring seals with clean
refrigerant oil and install them on the suction and
discharge line fittings. Use only the specified O-rings
as they are made of a special material for the R-134a
system. Use only refrigerant oil of the type recom-
mended for the A/C compressor in the vehicle.
(9) Connect the suction/discharge line assembly to
the compressor.
(10) Install and tighten the bolt that secures the
suction/discharge line assembly to the compressor.
Tighten the bolt to 28 N´m (20 ft. lbs.).
(11) Remove the tape or plugs from the discharge
line fitting and condenser inlet port.
(12) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the discharge line fit-
ting. Use only the specified O-ring as it is made of a
special material for the R-134a system. Use only
refrigerant oil of the type recommended for the A/C
compressor in the vehicle.
(13) Connect the discharge line to the condenser
inlet port.(14) Install and tighten the nut that secures the
discharge line fitting to the condenser. Tighten the
nut to 20 N´m (180 in. lbs.).
(15) Connect the wire harness connector to the A/C
pressure transducer.
(16) Reconnect the battery negative cable.
(17) Evacuate the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE).
(18) Charge the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE).
INSTALLATION - 3.7L/4.7L AND 5.7L HEMI
ENGINE
(1) Position the suction line into the engine com-
partment.
(2) Remove the tape or plugs from the suction line
fitting and the compressor inlet port.
(3) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the suction line fit-
ting. Use only the specified O-ring as it is made of a
special material for the R-134a system. Use only
refrigerant oil of the type recommended for the A/C
compressor in the vehicle.
(4) Connect the suction line to the compressor.
(5) Install and tighten the nut that secures the
suction line to the compressor. Tighten the nut to 28
N´m (20 ft. lbs.).
(6) Remove the tape or plugs from the suction line
and the accumulator outlet tube fitting.
(7) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the accumulator out-
let tube fitting. Use only the specified O-ring as it is
made of a special material for the R-134a system.
Use only refrigerant oil of the type recommended for
the A/C compressor in the vehicle.
(8) Connect the suction line to the accumulator
outlet tube (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING/REFRIGERANT LINE COU-
PLER - INSTALLATION).
(9) Install the secondary retaining clip onto the
spring-lock coupler that secures the suction line to
the accumulator outlet tube.
(10) Reconnect the battery negative cable.
(11) Evacuate the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE).
(12) Charge the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE).
Fig. 33 A/C Accumulator - Typical
1 - RH INNER FENDER
2 - ACCUMULATOR INLET TUBE
3 - A/C LINE SECONDARY RETAINING CLIP
4 - EVAPORATOR OUTLET TUBE
5 - BOLTS (2)
6 - ACCUMULATOR
7 - SUCTION LINE
8 - A/C LOW PRESSURE SERVICE PORT
9 - A/C LINE SECONDARY RETAINING CLIP
DRPLUMBING 24 - 73
SUCTION LINE (Continued)

DESCRIPTION - MONITORED SYSTEMS
There are new electronic circuit monitors that
check fuel, emission, engine and ignition perfor-
mance. These monitors use information from various
sensor circuits to indicate the overall operation of the
fuel, engine, ignition and emission systems and thus
the emissions performance of the vehicle.
The fuel, engine, ignition and emission systems
monitors do not indicate a specific component prob-
lem. They do indicate that there is an implied prob-
lem within one of the systems and that a specific
problem must be diagnosed.
If any of these monitors detect a problem affecting
vehicle emissions, the Malfunction Indicator Lamp
(MIL) will be illuminated. These monitors generate
Diagnostic Trouble Codes that can be displayed with
the MIL or a scan tool.
The following is a list of the system monitors:
²Misfire Monitor
²Fuel System Monitor
²Oxygen Sensor Monitor
²Oxygen Sensor Heater Monitor
²Catalyst Monitor
²Leak Detection Pump Monitor (if equipped)
All these system monitors require two consecutive
trips with the malfunction present to set a fault.
Refer to the appropriate Powertrain Diagnos-
tics Procedures manual for diagnostic proce-
dures.
The following is an operation and description of
each system monitor :
OXYGEN SENSOR (O2S) MONITOR
Effective control of exhaust emissions is achieved
by an oxygen feedback system. The most important
element of the feedback system is the O2S. The O2S
is located in the exhaust path. Once it reaches oper-
ating temperature 300É to 350ÉC (572É to 662ÉF), the
sensor generates a voltage that is inversely propor-
tional to the amount of oxygen in the exhaust. The
information obtained by the sensor is used to calcu-
late the fuel injector pulse width. This maintains a
14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio,
the catalyst works best to remove hydrocarbons (HC),
carbon monoxide (CO) and nitrogen oxide (NOx) from
the exhaust.
The O2S is also the main sensing element for the
Catalyst and Fuel Monitors.
The O2S can fail in any or all of the following
manners:
²slow response rate
²reduced output voltage
²dynamic shift
²shorted or open circuits
Response rate is the time required for the sensor to
switch from lean to rich once it is exposed to a richerthan optimum A/F mixture or vice versa. As the sen-
sor starts malfunctioning, it could take longer to
detect the changes in the oxygen content of the
exhaust gas.
The 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 con-
centrations 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.
OXYGEN SENSOR HEATER MONITOR
If there is an oxygen sensor (O2S) shorted to volt-
age DTC, as well as a O2S heater DTC, the O2S
fault MUST be repaired first. Before checking the
O2S fault, verify that the heater circuit is operating
correctly.
Effective control of exhaust emissions is achieved
by an oxygen feedback system. The most important
element of the feedback system is the O2S. The O2S
is located in the exhaust path. Once it reaches oper-
ating temperature 300É to 350ÉC (572 É to 662ÉF), the
sensor generates a voltage that is inversely propor-
tional to the amount of oxygen in the exhaust. The
information obtained by the sensor is used to calcu-
late the fuel injector pulse width. This maintains a
14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio,
the catalyst works best to remove hydrocarbons (HC),
carbon monoxide (CO) and nitrogen oxide (NOx) from
the exhaust.
The voltage readings taken from the O2S sensor
are very temperature sensitive. The readings are not
accurate below 300ÉC. Heating of the O2S sensor 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 sensor must be tested to ensure
that it is heating the sensor properly.
The O2S sensor circuit is monitored for a drop in
voltage. The sensor output is used to test the heater
by isolating the effect of the heater element on the
O2S sensor output voltage from the other effects.
LEAK DETECTION PUMP MONITOR (IF EQUIPPED)
The leak detection assembly incorporates two pri-
mary functions: it must detect a leak in the evapora-
tive system and seal the evaporative system so the
leak detection test can be run.
The primary components within the assembly are:
A three port solenoid that activates both of the func-
tions listed above; a pump which contains a switch,
two check valves and a spring/diaphragm, a canister
vent valve (CVV) seal which contains a spring loaded
vent seal valve.
25 - 2 EMISSIONS CONTROLDR
EMISSIONS CONTROL (Continued)

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 MILL 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.
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.
25 - 6 EMISSIONS CONTROLDR
EMISSIONS CONTROL (Continued)

FUEL FILLER CAP
DESCRIPTION
The plastic fuel tank filler tube cap is threaded
onto the end of the fuel fill tube. Certain models are
equipped with a 1/4 turn cap.
OPERATION
The loss of any fuel or vapor out of fuel filler tube
is prevented by the use of a pressure-vacuum fuel fill
cap. Relief valves inside the cap will release fuel tank
pressure at predetermined pressures. Fuel tank vac-
uum will also be released at predetermined values.
This cap must be replaced by a similar unit if
replacement is necessary. This is in order for the sys-
tem to remain effective.
CAUTION: Remove fill cap before servicing any fuel
system component to relieve tank pressure. If
equipped with a Leak Detection Pump (LDP), or
NVLD system, the cap must be tightened securely.
If cap is left loose, a Diagnostic Trouble Code (DTC)
may be set.
REMOVAL
REMOVAL/INSTALLATION
If replacement of the 1/4 turn fuel tank filler tube
cap is necessary, it must be replaced with an identi-
cal cap to be sure of correct system operation.
CAUTION: Remove the fuel tank filler tube cap to
relieve fuel tank pressure. The cap must be
removed prior to disconnecting any fuel system
component or before draining the fuel tank.
LEAK DETECTION PUMP
DESCRIPTION
Vehicles equipped with JTEC engine control mod-
ules use a leak detection pump. Vehicles equipped
with NGC engine control modules use an NVLD
pump. Refer to Natural Vacuum - Leak Detection
(NVLD) for additional information.
The evaporative emission system is designed to
prevent the escape of fuel vapors from the fuel sys-
tem (Fig. 4). Leaks in the system, even small ones,
can allow fuel vapors to escape into the atmosphere.
Government regulations require onboard testing to
make sure that the evaporative (EVAP) system is
functioning properly. The leak detection system tests
for EVAP system leaks and blockage. It also performs
self-diagnostics. During self-diagnostics, the Power-
train Control Module (PCM) first checks the Leak
Detection Pump (LDP) for electrical and mechanical
faults. If the first checks pass, the PCM then uses
the LDP to seal the vent valve and pump air into the
system to pressurize it. If a leak is present, the PCM
will continue pumping the LDP to replace the air
that leaks out. The PCM determines the size of the
leak based on how fast/long it must pump the LDP
as it tries to maintain pressure in the system.
EVAP LEAK DETECTION SYSTEM COMPONENTS
Service Port: Used with special tools like the Miller
Evaporative Emissions Leak Detector (EELD) to test
for leaks in the system.
EVAP Purge Solenoid: The PCM uses the EVAP
purge solenoid to control purging of excess fuel
vapors stored in the EVAP canister. It remains closed
during leak testing to prevent loss of pressure.
EVAP Canister: The EVAP canister stores fuel
vapors from the fuel tank for purging.
EVAP Purge Orifice: Limits purge volume.
EVAP System Air Filter: Provides air to the LDP
for pressurizing the system. It filters out dirt while
allowing a vent to atmosphere for the EVAP system.
Fig. 3 EVAP / DUTY CYCLE PURGE SOLENOID
1 - MOUNTING BRACKET
2 - VACUUM HARNESS
3 - DUTY CYCLE SOLENOID
4 - TEST PORT CAP AND TEST PORT
DREVAPORATIVE EMISSIONS 25 - 13
EVAP/PURGE SOLENOID (Continued)

IGNITION CIRCUIT SENSE -
DESCRIPTION.......................8E-10
IGNITION CIRCUIT SENSE - OPERATION . . 8E-11
IGNITION COIL - DESCRIPTION..........8I-11
IGNITION COIL - INSTALLATION.........8I-14
IGNITION COIL - OPERATION............8I-12
IGNITION COIL - REMOVAL.............8I-13
IGNITION COIL CAPACITOR -
DESCRIPTION........................8I-21
IGNITION COIL CAPACITOR -
INSTALLATION.......................8I-21
IGNITION COIL CAPACITOR - OPERATION . . 8I-21
IGNITION COIL CAPACITOR - REMOVAL . . . 8I-21
IGNITION COIL RESISTANCE, 3.7L V-6.....8I-5
IGNITION COIL RESISTANCE, 4.7L V-8.....8I-5
IGNITION COIL RESISTANCE, 5.7L V-8.....8I-5
IGNITION CONTROL - DESCRIPTION.......8I-1
IGNITION SWITCH - DESCRIPTION........19-9
IGNITION SWITCH - DESCRIPTION,
KEY-IN.............................19-11
IGNITION SWITCH - DIAGNOSIS AND
TESTING............................19-9
IGNITION SWITCH - INSTALLATION......19-11
IGNITION SWITCH - OPERATION.........19-9
IGNITION SWITCH - REMOVAL..........19-10
IGNITION SWITCH AND KEY LOCK
CYLINDER - DIAGNOSIS AND TESTING . . . 19-11
IGNITION TIMING, SPECIFICATIONS.......8I-5
IGNITION-OFF DRAW TEST - STANDARD
PROCEDURE........................8F-11
IMMOBILIZER MODULE - DESCRIPTION,
SENTRY KEY........................8E-13
IMMOBILIZER MODULE - INSTALLATION,
SENTRY KEY........................8E-15
IMMOBILIZER MODULE - OPERATION,
SENTRY KEY........................8E-13
IMMOBILIZER MODULE - REMOVAL,
SENTRY KEY........................8E-15
IMMOBILIZER MODULE (SKIM) -
DESCRIPTION, SENTRY KEY.............8Q-1
IMMOBILIZER MODULE (SKIM) -
OPERATION, SENTRY KEY..............8Q-2
IMMOBILIZER SYSTEM INDICATOR
LAMP - DESCRIPTION, SENTRY KEY......8Q-5
IMMOBILIZER SYSTEM INDICATOR
LAMP - OPERATION, SENTRY KEY........8Q-5
IMMOBILIZER SYSTEM INITIALIZATION,
STANDARD PROCEDURE - SENTRY
KEY................................8Q-3
IMMOBILIZER SYSTEM (SKIS) -
DESCRIPTION, SENTRY KEY.............8Q-1
IMMOBILIZER SYSTEM (SKIS) -
OPERATION, SENTRY KEY..............8Q-2
IMMOBILIZER SYSTEM TRANSPONDER
PROGRAMMING, STANDARD
PROCEDURE - SENTRY KEY.............8Q-4
IMPACT SENSOR - DESCRIPTION, SIDE . . 8O-59
IMPACT SENSOR - OPERATION, SIDE....8O-59
INCORRECT FLUID LEVEL - DIAGNOSIS
AND TESTING, EFFECTS OF......21-201,21-366
INDEPENDENT FRONT SUSPENSION -
DESCRIPTION, GEAR..................19-17
INDEPENDENT FRONT SUSPENSION -
INSTALLATION, GEAR.................19-18
INDEPENDENT FRONT SUSPENSION -
REMOVAL, GEAR.....................19-17
INDICATOR - DESCRIPTION, ABS........8J-17
INDICATOR - DESCRIPTION, AIRBAG.....8J-18
INDICATOR - DESCRIPTION, BRAKE/
PARK BRAKE........................8J-19
INDICATOR - DESCRIPTION, CARGO
LAMP
..............................8J-20
INDICATOR - DESCRIPTION, CHECK
GAUGES
............................8J-21
INDICATOR - DESCRIPTION, CRUISE
.....8J-22
INDICATOR - DESCRIPTION, DOOR AJAR
. . 8J-23
INDICATOR - DESCRIPTION, ETC
........8J-25
INDICATOR - DESCRIPTION, GEAR
SELECTOR
..........................8J-27
INDICATOR - DESCRIPTION, HIGH BEAM
. . 8J-28
INDICATOR - DESCRIPTION, LAMP OUT
. . . 8J-29
INDICATOR - DESCRIPTION, LOW FUEL
. . . 8J-30
INDICATOR - DESCRIPTION, SEATBELT
. . . 8J-34
INDICATOR - DESCRIPTION, SECURITY
. . . 8J-35
INDICATOR - DESCRIPTION, SERVICE
4WD
...............................8J-36
INDICATOR - DESCRIPTION, TOW/HAUL
. . . 8J-39INDICATOR - DESCRIPTION, TRANS
TEMP..............................8J-40
INDICATOR - DESCRIPTION, TURN
SIGNAL............................8J-40
INDICATOR - DESCRIPTION, UPSHIFT....8J-41
INDICATOR - DESCRIPTION, WAIT-TO-
START .............................8J-44
INDICATOR - DESCRIPTION, WASHER
FLUID..............................8J-44
INDICATOR - DESCRIPTION, WATER-IN-
FUEL..............................8J-45
INDICATOR - DIAGNOSIS AND TESTING,
BRAKE.............................8J-20
INDICATOR - OPERATION, ABS..........8J-17
INDICATOR - OPERATION, AIRBAG.......8J-18
INDICATOR - OPERATION, BRAKE/PARK
BRAKE.............................8J-19
INDICATOR - OPERATION, CARGO LAMP . . 8J-20
INDICATOR - OPERATION, CHECK
GAUGES............................8J-21
INDICATOR - OPERATION, CRUISE.......8J-22
INDICATOR - OPERATION, DOOR AJAR . . . 8J-23
INDICATOR - OPERATION, ETC..........8J-25
INDICATOR - OPERATION, GEAR
SELECTOR..........................8J-27
INDICATOR - OPERATION, HIGH BEAM....8J-28
INDICATOR - OPERATION, LAMP OUT....8J-29
INDICATOR - OPERATION, LOW FUEL.....8J-30
INDICATOR - OPERATION, SEATBELT.....8J-34
INDICATOR - OPERATION, SECURITY......8J-36
INDICATOR - OPERATION, SERVICE 4WD . . 8J-37
INDICATOR - OPERATION, TOW/HAUL....8J-39
INDICATOR - OPERATION, TRANS TEMP . . 8J-40
INDICATOR - OPERATION, TURN SIGNAL . . 8J-41
INDICATOR - OPERATION, UPSHIFT......8J-42
INDICATOR - OPERATION, WAIT-TO-
START .............................8J-44
INDICATOR - OPERATION, WASHER
FLUID..............................8J-44
INDICATOR - OPERATION, WATER-IN-
FUEL..............................8J-45
INDICATOR LAMP - DESCRIPTION,
SENTRY KEY IMMOBILIZER SYSTEM......8Q-5
INDICATOR LAMP - OPERATION,
SENTRY KEY IMMOBILIZER SYSTEM......8Q-5
INDICATOR LAMP (MIL) - DESCRIPTION,
MALFUNCTION.......................8J-31
INDICATOR LAMP (MIL) - OPERATION,
MALFUNCTION.......................8J-31
INDICATOR TEST - STANDARD
PROCEDURE, BUILT-IN................8F-10
INDICATORS - DIAGNOSIS AND
TESTING, TREAD WEAR................22-8
INERTIA HINGE COVER - INSTALLATION,
CENTER SEAT BACK..................23-77
INERTIA HINGE COVER - REMOVAL,
CENTER SEAT BACK..................23-77
INFLATION PRESSURES - DESCRIPTION,
TIRE................................22-7
INFO CENTER - DESCRIPTION,
ELECTRONIC VEHICLE.................8M-7
INFO CENTER - INSTALLATION,
ELECTRONIC VEHICLE.................8M-9
INFO CENTER - OPERATION,
ELECTRONIC VEHICLE.................8M-7
INFO CENTER - REMOVAL, ELECTRONIC
VEHICLE............................8M-9
INITIAL OPERATION - STANDARD
PROCEDURE, POWER STEERING
PUMP.............................19-40
INITIALIZATION, STANDARD PROCEDURE
- SENTRY KEY IMMOBILIZER SYSTEM....8Q-3
INJECTED RINGS - ASSEMBLY, WITH......3-13
INJECTED RINGS - DISASSEMBLY, WITH . . . 3-11
INJECTION PUMP - DESCRIPTION, FUEL . . 14-53
INJECTION PUMP - INSTALLATION, FUEL . 14-55
INJECTION PUMP - OPERATION, FUEL....14-53
INJECTION PUMP - REMOVAL, FUEL.....14-54
INJECTION PUMP TIMING - DIAGNOSIS
AND TESTING, FUEL..................14-53
INJECTOR - DESCRIPTION, FUEL . . . 14-26,14-74
INJECTOR - INSTALLATION, FUEL........14-77
INJECTOR - OPERATION, FUEL
.....14-26,14-74
INJECTOR - REMOVAL, FUEL
...........14-75
INJECTOR FIRING ORDER, DIESEL -
FUEL
..............................14-48
INJECTOR RAIL - DESCRIPTION, FUEL
....14-78
INJECTOR RAIL - INSTALLATION, FUEL
. . . 14-78INJECTOR RAIL - OPERATION, FUEL.....14-78
INJECTOR RAIL - REMOVAL, FUEL.......14-78
INLET AIR TEMPERATURE SENSOR/
PRESSURE SENSOR - DESCRIPTION.....14-79
INLET AIR TEMPERATURE SENSOR/
PRESSURE SENSOR - INSTALLATION.....14-79
INLET AIR TEMPERATURE SENSOR/
PRESSURE SENSOR - OPERATION.......14-79
INLET AIR TEMPERATURE SENSOR/
PRESSURE SENSOR - REMOVAL........14-79
INLET FILTER - INSTALLATION..........14-20
INLET FILTER - REMOVAL..............14-20
INLET HOSE - INSTALLATION, HEATER....24-64
INLET HOSE - REMOVAL, HEATER.......24-64
INNER BELT MOLDING - INSTALLATION,
FRONT DOOR.......................23-93
INNER BELT MOLDING - INSTALLATION,
REAR DOOR........................23-94
INNER BELT MOLDING - REMOVAL,
FRONT DOOR.......................23-93
INNER BELT MOLDING - REMOVAL,
REAR DOOR........................23-94
INPUT - OPERATION, ASD SENSE - PCM . . . 8I-5
INPUT CLUTCH ASSEMBLY - ASSEMBLY . 21-378
INPUT CLUTCH ASSEMBLY -
DESCRIPTION......................21-373
INPUT CLUTCH ASSEMBLY -
DISASSEMBLY......................21-374
INPUT CLUTCH ASSEMBLY - OPERATION . 21-373
INPUT SHAFT SEAL - INSTALLATION,
STEERING GEAR.......................19-29
INPUT SHAFT SEAL - REMOVAL,
STEERING GEAR.....................19-27
INPUT SPEED SENSOR - DESCRIPTION . . 21-382
INPUT SPEED SENSOR - INSTALLATION . 21-382
INPUT SPEED SENSOR - OPERATION....21-382
INPUT SPEED SENSOR - REMOVAL.....21-382
INSERTS - INSTALLATION, SPRING TIP....2-45
INSERTS - REMOVAL, SPRING TIP........2-44
INSIDE HANDLE ACTUATOR -
INSTALLATION..................23-22,23-32
INSIDE HANDLE ACTUATOR - REMOVAL . . 23-22,
23-31
INSTRUMENT CLUSTER - ASSEMBLY.....8J-15
INSTRUMENT CLUSTER - DESCRIPTION . . . 8J-2
INSTRUMENT CLUSTER - DIAGNOSIS
AND TESTING.......................8J-10
INSTRUMENT CLUSTER - DISASSEMBLY . . 8J-14
INSTRUMENT CLUSTER - INSTALLATION . . 8J-16
INSTRUMENT CLUSTER - OPERATION.....8J-6
INSTRUMENT CLUSTER - REMOVAL.....8J-14
INSTRUMENT PANEL ANTENNA CABLE -
INSTALLATION.......................8A-7
INSTRUMENT PANEL ANTENNA CABLE -
REMOVAL...........................8A-7
INSTRUMENT PANEL ASSEMBLY -
INSTALLATION.......................23-55
INSTRUMENT PANEL ASSEMBLY -
REMOVAL..........................23-52
INSTRUMENT PANEL CENTER BEZEL -
INSTALLATION.......................23-57
INSTRUMENT PANEL CENTER BEZEL -
REMOVAL..........................23-57
INSTRUMENT PANEL DEMISTER DUCTS
- INSTALLATION.....................24-37
INSTRUMENT PANEL DEMISTER DUCTS
- REMOVAL.........................24-36
INSTRUMENT PANEL DRIVER SIDE
BEZEL - INSTALLATION................23-58
INSTRUMENT PANEL DRIVER SIDE
BEZEL - REMOVAL...................23-58
INSTRUMENT PANEL DUCTS -
INSTALLATION.......................24-37
INSTRUMENT PANEL DUCTS - REMOVAL . 24-37
INSTRUMENT PANEL HEADLAMP
SWITCH BEZEL - INSTALLATION.........23-56
INSTRUMENT PANEL HEADLAMP
SWITCH BEZEL - REMOVAL............23-56
INSTRUMENT PANEL LOWER
SURROUND - INSTALLATION...........23-59
INSTRUMENT PANEL LOWER
SURROUND - REMOVAL
...............23-59
INSTRUMENT PANEL TOP COVER -
INSTALLATION
.......................23-59
INSTRUMENT PANEL TOP COVER -
REMOVAL
..........................23-58
INTAKE AIR HEATER - DESCRIPTION
.....14-80
INTAKE AIR HEATER - INSTALLATION
.....14-80
DRINDEX 17
Description Group-Page Description Group-Page Description Group-Page