2002 CHRYSLER VOYAGER Ignition section

tion of the service manual for complete IPM circuit
schematics.
REMOVAL
(1) Disconnect the negative and positive battery
cables.
(2) Remove the battery thermal guard from the
vehicle. Refer to the Battery section for the proce-
dure.
(3) Remove the battery from the vehicle. Refer to
the Battery section for the procedure.
(4) Using a flat-bladed screwdriver, twist the Inte-
grated Power Module (IPM) bracket retaining latch
outward to free the intelligent power module from its
mounting bracket (Fig. 3).
(5) Rotate the IPM counter-clockwise to access and
disconnect the various electrical connectors (Fig. 4).
(6) Free the IPM from its mounting bracket by
removing the IPM bracket clips from the hinge. A
screwdriver slipped up from under the hinge will free
the clips.
INSTALLATION
(1) Snap the left side of the Integrated Power Mod-
ule (IPM) housing in its mounting bracket and con-
nect the various electrical connectors. Care must be
taken that the Connector Positive Assurance (CPA)
on the five-pin B+ connector is positively engaged to
prevent generating a Diagnostic Trouble Code (DTC).
NOTE: IPM electrical connectors are color coded to
ease location reference.(2) Being certain no wires are stressed or pinched,
rotate the IPM clock-wise until secured in mounting
bracket. An audible click may be heard.
(3) Install the battery in the vehicle. Refer to the
Battery section for the procedure.
(4) Install the battery thermal guard in the vehi-
cle. Refer to the Battery section for the procedure.
(5)
Connect the negative and positive battery cables.
(6) Using a diagnostic scan tool, check for any
stored diagnostic trouble codes and correct, check
that all vehicle options are operational before return-
ing the vehicle to service.
IOD FUSE
DESCRIPTION
All vehicles are equipped with an Ignition-Off
Draw (IOD) fuse that is removed from its normal
cavity in the Integrated Power Module (IPM) when
the vehicle is shipped from the factory. Dealer per-
sonnel are to remove the IOD fuse from the storage
location and install it into the IPM fuse cavity
marked IOD as part of the preparation procedures
performed just prior to new vehicle delivery.
The IPM has a molded plastic cover that can be
removed to provide service access to all of the fuses
and relays in the IPM. An integral latch and hinges
are molded into the IPM cover for easy removal. A
fuse layout map is integral to the underside of the
IPM cover to ensure proper fuse and relay identifica-
Fig. 3 RELEASING INTEGRATED POWER MODULE
FROM ITS MOUNTING BRACKET
Fig. 4 DISCONNECTING IPM
1 - INTEGRATED POWER MODULE FUSE & RELAY CENTER
8W - 97 - 4 8W-97 POWER DISTRIBUTION SYSTEMRS
INTEGRATED POWER MODULE (Continued)
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(11) Install air cleaner and air inlet hose assembly.
(12) Connect the inlet air temperature (IAT) sen-
sor electrical connector.
(13) Connect battery negative cable.
INTAKE MANIFOLD - LOWER
REMOVAL - LOWER INTAKE MANIFOLD
(1) Perform fuel system pressure release procedure
(before attempting any repairs).(Refer to 14 -
FUEL SYSTEM/FUEL DELIVERY - STANDARD
PROCEDURE)
(2) Drain the cooling system. (Refer to 7 - COOL-
ING - STANDARD PROCEDURE)
(3) Remove the upper intake manifold. (Refer to 9
- ENGINE/MANIFOLDS/INTAKE MANIFOLD -
REMOVAL)
(4) Remove the fuel line. (Refer to 14 - FUEL SYS-
TEM/FUEL DELIVERY/FUEL LINES - STANDARD
PROCEDURE) (Refer to 14 - FUEL SYSTEM/FUEL
DELIVERY/QUICK CONNECT FITTING - STAN-
DARD PROCEDURE)
(5) Remove ignition coil and bracket (Fig. 125).
(6) Disconnect heater supply hose and engine cool-
ant temperature sensor (Fig. 126).
(7) Disconnect the fuel injector wire harness.
(8) Remove the fuel injectors and rail assembly
(Fig. 125).
(9) Remove radiator upper hose.
(10) Remove the intake manifold bolts.
(11) Remove lower intake manifold (Fig. 127).
WARNING: INTAKE MANIFOLD GASKET IS MADE
OF VERY THIN METAL AND MAY CAUSE PER-
SONAL INJURY, HANDLE WITH CARE.
(12) Remove intake manifold seal retainers screws
(Fig. 127). Remove intake manifold gasket.
(13) Inspect and clean manifold. (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
INSPECTION) (Refer to 9 - ENGINE/MANIFOLDS/
INTAKE MANIFOLD - CLEANING)
CLEANING
(1) Discard gasket(s).
(2) Clean all sealing surfaces.
INSPECTION
Check for:
²Damage and cracks of each section.
²Clogged water passages in end cross-overs (if
equipped).
²Check for cylinder head mounting surface distor-
tion using a straightedge and thickness gauge. (Refer
to 9 - ENGINE/CYLINDER HEAD - INSPECTION)
INSTALLATION - LOWER INTAKE MANIFOLD
(1) Place a bead (approximately 1/4 in. diameter)
of MopartEngine RTV GEN II onto each of thefour
manifold to cylinder head gasket corners (Fig. 128).
(2) Carefully install the new intake manifold gas-
ket (Fig. 127). Tighten end seal retainer screws to 12
N´m (105 in. lbs.).
(3) Install lower intake manifold (Fig. 127). Install
the bolts and torque to 1 N´m (10 in. lbs.). Then
torque bolts to 22 N´m (200 in. lbs.) in sequence
shown in (Fig. 129). Then torque again to 22 N´m
(200 in. lbs.). After intake manifold is in place,
inspect to make sure seals are in place.
(4) Install the fuel injectors and rail assembly.
(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY/
FUEL RAIL - INSTALLATION)
(5) Connect fuel injector electrical harness.
Fig. 125 FUEL RAIL AND IGNITION COIL &
BRACKET
1 - FUEL RAIL
2 - BOLT - FUEL RAIL
3 - NUT - IGNITION COIL
4 - BOLT - IGNITION COIL
5 - IGNITION COIL
6 - BRACKET - IGNITION COIL
7 - STUD - IGNITION COIL
8 - SEPARATOR - SPARK PLUG CABLE
9 - BRACKET - SPARK PLUG CABLE SEPARATOR
10 - BOLT - SEPARATOR BRACKET
11 - BRACKET - SPARK PLUG CABLE SEPARATOR
9 - 150 ENGINE 3.3/3.8LRS
INTAKE MANIFOLD - UPPER (Continued)
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FUEL DELIVERY
DESCRIPTION
DESCRIPTION
The front wheel drive car uses a plastic fuel tank
located rear center of the vehicle.
The Fuel Delivery System consists of: the following
items:
²Electric fuel pump module
²Fuel filter
²Tubes/lines/hoses
²Fuel injectors
The in-tank fuel pump module contains the fuel
pump. The pump is serviced as part of the fuel pump
module. Refer to Fuel Pump Module.
The fuel filter is replaceable, it is mounted on the
outside, on top of, the fuel tank. Refer to the Main-
tenance Schedules in the Introduction section of this
manual for recommended fuel filter replacement
intervals.
DESCRIPTION - FFV REPLACEMENT PARTS
Many components in a Flexible Fuel Vehicle (FFV)
are designed to be compatible with ethanol. Always
be sure that the vehicle is serviced with correct etha-
nol compatible parts.
CAUTION: Replacing fuel system components with
non-ethanol compatible components can damage
your vehicle and may void the warranty.
OPERATION
The fuel system provides fuel pressure by an
in-tank pump module. The PCM controls the opera-
tion of the fuel system by providing battery voltage
to the fuel pump through the fuel pump relay. The
PCM requires only three inputs and a good ground to
operate the fuel pump relay. The three inputs are:²Ignition voltage
²Crankshaft Position (CKP) sensor
²Camshaft Position (CMP) sensor
DIAGNOSIS AND TESTING - FUEL DELIVERY
SYSTEM
(Refer to Appropriate Diagnostic Information)
STANDARD PROCEDURE
STANDARD PROCEDURE - FUEL SYSTEM
PRESSURE RELEASE PROCEDURE
(1) Remove Fuel Pump relay from Power Distribu-
tion Center (PDC). For location of relay, refer to label
on underside of PDC cover.
(2) Start and run engine until it stalls.
(3) Attempt restarting engine until it will no
longer run.
(4) Turn ignition key to OFF position.
(5) Return fuel pump relay to PDC.
(6) One or more Diagnostic Trouble Codes (DTC's)
may have been stored in PCM memory due to fuel
pump relay removal. The DRB IIItscan tool must be
used to erase a DTC.
STANDARD PROCEDURE - DRAINING FUEL
TANK
(1) Release fuel system pressure, refer to the Fuel
System Release Procedure in this section.
(2) Insert a 1/4 inch siphon (max. O. D. 5/16) hose
from a portable fuel siphoning tank through the fuel
filler neck opening into the fuel tank. Hose most
have a 30 degree angle cut on the end to bypass the
check valve in the end of the filler neck. Refer to the
siphoning tank's Manufacturing Instructions.
(3) Drain fuel from fuel tank into siphoning tank.
14 - 2 FUEL DELIVERYRS
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FUEL PUMP MODULE
DESCRIPTION
The fuel pump module is installed in the top of the
fuel tank (Fig. 10) .
The fuel pump module contains the following:
²Electric fuel pump
²Fuel pump reservoir
²Inlet strainer
²Fuel pressure regulator
²Fuel gauge sending unit
²Fuel supply line connection
The inlet strainer, fuel pressure regulator
and fuel level sensor are the only serviceable
items. If the fuel pump or electrical wiring har-
ness requires service, replace the fuel pump
module.
The electric fuel pump is located in and is part of
the fuel pump module. It is a positive displacement,
gerotor type, immersible pump with a permanent
magnet electric motor.
OPERATION
The pump draws fuel through a strainer and
pushes it through the motor to the outlet. The pump
contains one check valve. The check valve, in the
pump outlet, maintains pump pressure during engine
off conditions. The fuel pump relay provides voltage
to the fuel pump.
The fuel pump has a maximum deadheaded pres-
sure output of approximately 880 kPa (130 psi). The
regulator adjusts fuel system pressure to approxi-
mately 400  34 kPa (58  5 psi).
FUEL PUMP ELECTRICAL CONTROL
Voltage to operate the electric pump is supplied
through the fuel pump relay. For an electrical opera-tional description of the fuel pump refer to fuel Pump
RelayÐPCM Output.
ELECTRICAL PUMP REPLACEMENT
The electric fuel pump is not serviceable. If the
fuel pump or electrical wiring harness needs replace-
ment, the complete fuel pump module must be
replaced. Perform the Fuel System Pressure Release
procedure before servicing the fuel pump.
REMOVAL
WARNING: RELEASE FUEL SYSTEM PRESSURE
BEFORE SERVICING FUEL SYSTEM COMPONENTS.
SERVICE VEHICLES IN WELL VENTILATED AREAS
AND AVOID IGNITION SOURCES. NEVER SMOKE
WHILE SERVICING THE VEHICLE.
(1) Remove fuel filler cap and perform Fuel Sys-
tem Pressure Release procedure.
(2) Disconnect negative cable from auxiliary
jumper terminal.
(3) Drain fuel tank, refer to the Fuel Tank proce-
dure in the Fuel Delivery section.
(4) Remove fuel tank, refer to the Fuel Tank
removal section.
(5) Clean top of tank to remove loose dirt and
debris.
(6) Using a brass punch and hammer remove lock-
nut to release pump module (Fig. 11).
Fig. 10 Fuel Pump Module
1 - INLET STRAINER
2 - FUEL RESERVOIR
3 - FUEL PRESSURE REGULATOR
4 - FUEL LEVEL SENSOR
Fig. 11 FUEL PUMP MODULE LOCKING RING
14 - 8 FUEL DELIVERYRS
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FUEL INJECTION
OPERATION
OPERATION - INJECTION SYSTEM
All engines used in this section have a sequential
Multi-Port Electronic Fuel Injection system. The MPI
system is computer regulated and provides precise
air/fuel ratios for all driving conditions. The Power-
train Control Module (PCM) operates the fuel injec-
tion system.
The PCM regulates:
²Ignition timing
²Air/fuel ratio
²Emission control devices
²Cooling fan
²Charging system
²Idle speed
²Vehicle speed control
Various sensors provide the inputs necessary for
the PCM to correctly operate these systems. In addi-
tion to the sensors, various switches also provide
inputs to the PCM.
The PCM can adapt its programming to meet
changing operating conditions.
Fuel is injected into the intake port above the
intake valve in precise metered amounts through
electrically operated injectors. The PCM fires the
injectors in a specific sequence. Under most operat-
ing conditions, the PCM maintains an air fuel ratio
of 14.7 parts air to 1 part fuel by constantly adjust-
ing injector pulse width. Injector pulse width is the
length of time the injector is open.
The PCM adjusts injector pulse width by opening
and closing the ground path to the injector. Engine
RPM (speed) and manifold absolute pressure (air
density) are theprimaryinputs that determine
injector pulse width.
OPERATION - MODES OF OPERATION
As input signals to the PCM change, the PCM
adjusts its response to output devices. For example,
the PCM must calculate a different injector pulse
width and ignition timing for idle than it does for
Wide Open Throttle (WOT). There are several differ-
ent modes of operation that determine how the PCM
responds to the various input signals.
There are two different areas of operation, OPEN
LOOP and CLOSED LOOP.
During OPEN LOOP modes the PCM receives
input signals and responds according to preset PCM
programming. Inputs from the upstream and down-
stream heated oxygen sensors are not monitored dur-
ing OPEN LOOP modes, except for heated oxygensensor diagnostics (they are checked for shorted con-
ditions at all times).
During CLOSED LOOP modes the PCM monitors
the inputs from the upstream and downstream
heated oxygen sensors. The upstream heated oxygen
sensor input tells the PCM if the calculated injector
pulse width resulted in the ideal air-fuel ratio of 14.7
to one. By monitoring the exhaust oxygen content
through the upstream heated oxygen sensor, the
PCM can fine tune injector pulse width. Fine tuning
injector pulse width allows the PCM to achieve opti-
mum fuel economy combined with low emissions.
For the PCM to enter CLOSED LOOP operation,
the following must occur:
(1) Engine coolant temperature must be over 35ÉF.
²If the coolant is over 35ÉF the PCM will wait 38
seconds.
²If the coolant is over 50ÉF the PCM will wait 15
seconds.
²If the coolant is over 167ÉF the PCM will wait 3
seconds.
(2) For other temperatures the PCM will interpo-
late the correct waiting time.
(3) O2 sensor must read either greater than 0.745
volts or less than 0.29 volt.
(4) The multi-port fuel injection systems has the
following modes of operation:
²Ignition switch ON (Zero RPM)
²Engine start-up
²Engine warm-up
²Cruise
²Idle
²Acceleration
²Deceleration
²Wide Open Throttle
²Ignition switch OFF
(5) The engine start-up (crank), engine warm-up,
deceleration with fuel shutoff and wide open throttle
modes are OPEN LOOP modes. Under most operat-
ing conditions, the acceleration, deceleration (with
A/C on), idle and cruise modes,with the engine at
operating temperatureare CLOSED LOOP modes.
IGNITION SWITCH ON (ZERO RPM) MODE
When the ignition switch activates the fuel injec-
tion system, the following actions occur:
²The PCM monitors the engine coolant tempera-
ture sensor and throttle position sensor input. The
PCM determines basic fuel injector pulse width from
this input.
²The PCM determines atmospheric air pressure
from the MAP sensor input to modify injector pulse
width.
When the key is in the ON position and the engine
is not running (zero rpm), the Auto Shutdown (ASD)
and fuel pump relays de-energize after approximately
RSFUEL INJECTION14-17
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1 second. Therefore, battery voltage is not supplied to
the fuel pump, ignition coil, fuel injectors and heated
oxygen sensors.
ENGINE START-UP MODE
This is an OPEN LOOP mode. If the vehicle is in
park or neutral (automatic transaxles) or the clutch
pedal is depressed (manual transaxles) the ignition
switch energizes the starter relay. The following
actions occur when the starter motor is engaged.
²If the PCM receives the camshaft position sensor
and crankshaft position sensor signals, it energizes
the Auto Shutdown (ASD) relay and fuel pump relay.
If the PCM does not receive both signals within
approximately one second, it will not energize the
ASD relay and fuel pump relay. The ASD and fuel
pump relays supply battery voltage to the fuel pump,
fuel injectors, ignition coil, (EGR solenoid and PCV
heater if equipped) and heated oxygen sensors.
²The PCM energizes the injectors (on the 69É
degree falling edge) for a calculated pulse width until
it determines crankshaft position from the camshaft
position sensor and crankshaft position sensor sig-
nals. The PCM determines crankshaft position within
1 engine revolution.
²After determining crankshaft position, the PCM
begins energizing the injectors in sequence. It adjusts
injector pulse width and controls injector synchroni-
zation by turning the individual ground paths to the
injectors On and Off.
²When the engine idles within  64 RPM of its
target RPM, the PCM compares current MAP sensor
value with the atmospheric pressure value received
during the Ignition Switch On (zero RPM) mode.
Once the ASD and fuel pump relays have been
energized, the PCM determines injector pulse width
based on the following:
²MAP
²Engine RPM
²Battery voltage
²Engine coolant temperature
²Inlet/Intake air temperature (IAT)
²Throttle position
²The number of engine revolutions since cranking
was initiated
During Start-up the PCM maintains ignition tim-
ing at 9É BTDC.
ENGINE WARM-UP MODE
This is an OPEN LOOP mode. The following inputs
are received by the PCM:
²Manifold Absolute Pressure (MAP)
²Crankshaft position (engine speed)
²Engine coolant temperature
²Inlet/Intake air temperature (IAT)
²Camshaft position²Knock sensor
²Throttle position
²A/C switch
²Battery voltage
²Vehicle speed
²Speed control
²O2 sensors
The PCM adjusts injector pulse width and controls
injector synchronization by turning the individual
ground paths to the injectors On and Off.
The PCM adjusts ignition timing and engine idle
speed. Engine idle speed is adjusted through the idle
air control motor.
CRUISE OR IDLE MODE
When the engine is at operating temperature this
is a CLOSED LOOP mode. During cruising or idle
the following inputs are received by the PCM:
²Manifold absolute pressure
²Crankshaft position (engine speed)
²Inlet/Intake air temperature
²Engine coolant temperature
²Camshaft position
²Knock sensor
²Throttle position
²Exhaust gas oxygen content
²A/C control positions
²Battery voltage
²Vehicle speed
The PCM adjusts injector pulse width and controls
injector synchronization by turning the individual
ground paths to the injectors On and Off.
The PCM adjusts engine idle speed and ignition
timing. The PCM adjusts the air/fuel ratio according
to the oxygen content in the exhaust gas (measured
by the upstream and downstream heated oxygen sen-
sor).
The PCM monitors for engine misfire. During
active misfire and depending on the severity, the
PCM either continuously illuminates or flashes the
malfunction indicator lamp (Check Engine light on
instrument panel). Also, the PCM stores an engine
misfire DTC in memory, if 2nd trip with fault.
The PCM performs several diagnostic routines.
They include:
²Oxygen sensor monitor
²Downstream heated oxygen sensor diagnostics
during open loop operation (except for shorted)
²Fuel system monitor
²EGR monitor (if equipped)
²Purge system monitor
²Catalyst efficiency monitor
²All inputs monitored for proper voltage range,
rationality.
²All monitored components (refer to the Emission
section for On-Board Diagnostics).
14 - 18 FUEL INJECTIONRS
FUEL INJECTION (Continued)
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(5) Place key cylinder in RUN position. Depress
lock cylinder retaining tab and remove key cylinder
(Fig. 11).
(6) Remove ignition switch mounting screw (Fig.
12) with a #10 Torxttamper proof bit.
(7) Depress retaining tab (Fig. 8) or (Fig. 13) and
gently pry ignition switch from steering column (Fig.
14).
(8) Disconnect electrical connectors from ignition
switch and remove switch (Fig. 15).
INSTALLATION
The ignition switch attaches to the lock cylinder
housing on the end opposite the lock cylinder (Fig. 7)
. For ignition switch terminal and circuit identifica-
tion, refer to the Wiring Diagrams section.
(1) Ensure the ignition switch is in the RUN posi-
tion and the actuator shaft in the lock housing is in
the RUN position.
(2) Install electrical connectors to ignition switch.
Fig. 11 Lock Cylinder Retaining Tab
1 - IGNITION SWITCH
2 - RETAINING TAB
Fig. 12 Ignition Switch Mounting Screw
1 - MOUNTING SCREW
2 - IGNITION SWITCH
Fig. 13 Ignition Switch Retaining Tab
1 - IGNITION SWITCH
2 - RETAINING TAB
Fig. 14 Removing Ignition Switch
1 - IGNITION SWITCH
2 - RETAINING TAB
19 - 16 COLUMNRS
IGNITION SWITCH (Continued)
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nation by this diagnostic. When the vacuum in the
system exceeds about 19H2O (0.25 KPA), a vacuum
switch closes. The switch closure sends a signal to
the NGC. The NGC, via appropriate logic strategies
(described below), utilizes the switch signal, or lack
thereof, to make a determination of whether a leak is
present.
The NVLD device is designed with a normally open
vacuum switch, a normally closed solenoid, and a
seal, which is actuated by both the solenoid and a
diaphragm. The NVLD is located on the atmospheric
vent side of the canister. The NVLD assembly may
be mounted on top of the canister outlet, or in-line
between the canister and atmospheric vent filter. The
normally open vacuum switch will close with about 19
H2O (0.25 KPA) vacuum in the evaporative system.
The diaphragm actuates the switch. This is above the
opening point of the fuel inlet check valve in the fill
tube so cap off leaks can be detected. Submerged fill
systems must have recirculation lines that do not
have the in-line normally closed check valve that pro-
tects the system from failed nozzle liquid ingestion,
in order to detect cap off conditions.
The normally closed valve in the NVLD is intended
to maintain the seal on the evaporative system dur-
ing the engine off condition. If vacuum in the evapo-
rative system exceeds 39to 69H2O (0.75 to 1.5 KPA),
the valve will be pulled off the seat, opening the seal.
This will protect the system from excessive vacuum
as well as allowing sufficient purge flow in the event
that the solenoid was to become inoperative.
The solenoid actuates the valve to unseal the can-
ister vent while the engine is running. It also will be
used to close the vent during the medium and large
leak tests and during the purge flow check. This sole-
noid requires initial 1.5 amps of current to pull the
valve open but after 100 ms. will be duty cycled down
to an average of about 150 mA for the remainder of
the drive cycle.
Another feature in the device is a diaphragm that
will open the seal in the NVLD with pressure in the
evaporative system. The device will9blow off9at
about 0.59H2O (0.12 KPA) pressure to permit the
venting of vapors during refueling. An added benefit
to this is that it will also allow the tank to9breathe9
during increasing temperatures, thus limiting the
pressure in the tank to this low level. This is benefi-
cial because the induced vacuum during a subse-
quent declining temperature will achieve the switch
closed (pass threshold) sooner than if the tank had to
decay from a built up pressure.
The device itself has 3 wires: Switch sense, sole-
noid driver and ground. It also includes a resistor to
protect the switch from a short to battery or a short
to ground. The NGC utilizes a high-side driver to
energize and duty-cycle the solenoid.DESCRIPTION - HIGH AND LOW LIMITS
The PCM compares input signal voltages from each
input device with established high and low limits for
the device. If the input voltage is not within limits
and other criteria are met, the PCM stores a diagnos-
tic trouble code in memory. Other diagnostic trouble
code criteria might include engine RPM limits or
input voltages from other sensors or switches that
must be present before verifying a diagnostic trouble
code condition.
OPERATION
OPERATION - SYSTEM
The Powertrain Control Module (PCM) monitors
many different circuits in the fuel injection, ignition,
emission and engine systems. If the PCM senses a
problem with a monitored circuit often enough to
indicate an actual problem, it stores a Diagnostic
Trouble Code (DTC) in the PCM's memory. If the
code applies to a non-emissions related component or
system, and the problem is repaired or ceases to
exist, the PCM cancels the code after 40 warmup
cycles. Diagnostic trouble codes that affect vehicle
emissions illuminate the Malfunction Indicator Lamp
(MIL). Refer to Malfunction Indicator Lamp in this
section.
Certain criteria must be met before the PCM
stores a DTC in memory. The criteria may be a spe-
cific range of engine RPM, engine temperature,
and/or input voltage to the PCM.
The PCM might not store a DTC for a monitored
circuit even though a malfunction has occurred. This
may happen because one of the DTC criteria for the
circuit has not been met.For example, assume the
diagnostic trouble code criteria requires the PCM to
monitor the circuit only when the engine operates
between 750 and 2000 RPM. Suppose the sensor's
output circuit shorts to ground when engine operates
above 2400 RPM (resulting in 0 volt input to the
PCM). Because the condition happens at an engine
speed above the maximum threshold (2000 rpm), the
PCM will not store a DTC.
There are several operating conditions for which
the PCM monitors and sets DTC's. Refer to Moni-
tored Systems, Components, and Non-Monitored Cir-
cuits in this section.
NOTE: Various diagnostic procedures may actually
cause a diagnostic monitor to set a DTC. For
instance, pulling a spark plug wire to perform a
spark test may set the misfire code. When a repair
is completed and verified, use the DRBIIITscan tool
to erase all DTC's and extinguish the MIL.
RSEMISSIONS CONTROL25-9
EMISSIONS CONTROL (Continued)
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