2004 CHRYSLER VOYAGER ECO mode

(6) Rotate the SKREEM upwards and then to the
side away from the steering column to slide the
SKREEM antenna ring from around the ignition
switch lock cylinder housing.
(7) Remove the SKREEM from the vehicle.
INSTALLATION
(1) Slip the Sentry Key Remote Entry Module
(SKREEM) antenna ring around the ignition switch
lock cylinder housing. Rotate the SKREEM down-
wards and then towards the steering column.
(2) Install the one screws securing the SKREEM to
the steering column.
(3) Connect the steering column wire harness to
the SKREEM.
(4) Install the steering column upper and lower
shrouds (Refer to 19 - STEERING/COLUMN/UPPER
SHROUD - INSTALLATION) and (Refer to 19 -
STEERING/COLUMN/LOWER SHROUD - INSTAL-
LATION).
(5) Install the Steering Column Opening Cover
(Refer to 23 - BODY/INSTRUMENT PANEL/STEER-
ING COLUMN OPENING COVER - INSTALLA-
TION)
(6) Connect the battery negative cable.
TRANSPONDER KEY
DESCRIPTION
The Sentry Key Remote Entry System (SKREES)
uses a transponder chip that is integral to each igni-
tion key to communicate with the Sentry Key Remote
Entry Module (SKREEM). Ignition keys are supplied
with the vehicle when it is shipped from the factory.
The transponder chip is undermolded within the
head of the key.
OPERATION
Each Sentry Key has a unique transponder identi-
fication code permanently programmed into it by the
manufacturer. Likewise, the Sentry Key Remote
Entry Module (SKREEM) has a unique9Secret Key9
code programmed into it by the manufacturer as
well. When a Sentry Key is programmed into the
memory of the SKREEM, the SKREEM stores the
transponder identification code from the Sentry Key,
and the Sentry Key learns the9Secret Key9code from
the SKREEM. Once the Sentry Key learns the
9Secret Key9code of the SKREEM, it is also perma-
nently programmed into the transponder's memory.
Therefore, blank keys for the Sentry Key Remote
Entry System (SKREES) must be programmed by
the SKREEM in addition to being cut to match the
mechanical coding of the ignition lock cylinder. Refer
to Electrical, Vehicle Theft Security, TransponderKey, Standard Procedure - Transponder Program-
ming.
The Sentry Key's transponder is within the range
of the SKREEM's transceiver antenna ring when it is
inserted into the ignition lock cylinder. When the
ignition switch is turned to the ON position, the
SKREEM communicates with the Sentry Key via a
radio frequency (RF) signal. The SKREEM deter-
mines if a valid key is present based on the informa-
tion it receives from the Sentry Key. If a valid key is
detected, that fact is communicated to the PCM via
the PCI bus and the vehicle is allowed to continue
running. If an invalid key is received by the PCM or
no status at all is communicated, the vehicle will
stall after two (2) seconds of running. The indicator
light will be flashing at this point. The Sentry Key's
transponder can not be repaired. If it is faulty or
damaged, it must be replaced.
Common communication problems:
²Two transponder keys too close together.
²Speed Pass too close to transponder key.
Solid indicator that there is a system failure.
²Loss of PCM communication.
²Failed antenna circuit.
STANDARD PROCEDURE - TRANSPONDER
PROGRAMMING
USING A DRBIIITSCAN TOOL
All Sentry Keys included with the vehicle are pre-
programmed to work with the Sentry Key Remote
Entry System (SKREES) when it is shipped from the
factory. The Sentry Key Remote Entry Module
(SKREEM) can be programmed to recognize up to a
total of eight Sentry Keys. When programming a
blank Sentry Key transponder, the key must first be
cut to match the ignition lock cylinder of the vehicle
for which it will be used. The vehicle's four digit PIN
code will be required to complete this task since you
will need it to enter the Secured Access Mode in the
SKREEM. The following steps must be completed
using a DRBIIItscan tool:
(1) Insert the blank key into the ignition and turn
it to the RUN position.
(2) Using a DRBIIItscan tool, select9Theft
Alarm,99SKREEM,99Miscellaneous,9and then9Pro-
gram New Key.9
(3) Enter the four digit PIN code using the
DRBIIItscan tool. When programming is completed,
the SKREEM will exit Secured Access Mode and the
DRBIIItscan tool will display the results of your
attempt to program the key. One of five distinct
results may be displayed. All five are listed below:
²(Programming Successful(is displayed if the
Sentry Key programming is successful.
8Q - 6 VEHICLE THEFT SECURITYRS
SENTRY KEY REMOTE ENTRY MODULE (Continued)

²(Learned Key in Ignition(is displayed if the
key in the ignition has already been programmed
into that vehicle's SKREEM.
²(Eight Keys Already Learned (At The Maxi-
mum) Programming Not Done(is displayed if
eight keys have already been programmed into the
SKREEM. In this case, if a new key needs to be
added due to a lost or defective key, the9Erase All
Keys9command (which requires entering the Secured
Access Mode) has to be performed. Following the
9Erase All Keys9command, all keys that will be used
to operate the vehicleMUSTbe reprogrammed to
the SKREEM.
²(Programming Not Attempted(is displayed
after an9Erase All Keys9function is executed.
²(Programming Key Failed(is displayed if fur-
ther diagnosis is required.
To learn additional keys, turn the ignition OFF,
remove the learned key, insert the next new blank
key, and repeat the steps from the beginning.
ªCUSTOMER LEARNº MODE
This feature is only available on domestic vehicles
or those which have a U.S. country code designator.
This procedure requires access to at least two valid
Sentry Keys. If two valid Sentry Keys are not avail-
able, Sentry Key programming will require the use of
a DRBIIItscan tool.
The steps required to program Sentry Keys with
two valid Sentry Keys follows:
(1) Obtain the blank Sentry Key(s) that need to be
programmed. Cut the keys to match the ignition lock
cylinder mechanical key codes.
(2) Insert one of the two valid Sentry Keys into the
ignition switch and turn the ignition switch to the
ON position.
(3) After the ignition switch has been in the ON
position for longer than three seconds, but no more
than fifteen seconds, cycle the ignition switch back to
the OFF position. Replace the first valid Sentry Key
in the ignition lock cylinder with the second valid
Sentry Key and turn the ignition switch back to the
ON position. The second valid Sentry Key must be
inserted within 15 seconds of removing the first valid
Sentry key.
(4) About ten seconds after the completion of Step
3, the indicator light will start to flash and a single
audible chime tone will sound to indicate that the
system has entered the9Customer Learn9program-
ming mode.
(5) Within sixty seconds of entering the9Customer
Learn9programming mode, turn the ignition switch
to the OFF position, replace the valid Sentry Key
with a blank Sentry Key transponder, and turn the
ignition switch back to the ON position.(6) About ten seconds after the completion of Step
5, a single audible chime tone will sound and the
indicator light will stop flashing and stay on solid for
three seconds and then turn off to indicate that the
blank Sentry Key has been successfully programmed.
The SKREES will immediately exit the9Customer
Learn9programming mode and the vehicle may be
started using the newly programmed Sentry Key.
NOTE: The Remote Keyless Entry (RKE) Transmitter
will also be programmed during this procedure.
These steps must be completed in their entirety for
each additional Sentry Key to be programmed. If any
of the above steps are not completed in the given
sequence, or within the allotted time, the SKREES
will exit the9Customer Learn9programming mode
and the programming will be unsuccessful. The
SKREES will also automatically exit the9Customer
Learn9programming mode if:
²It sees a non-blank Sentry Key when it should
see a blank.
²If it has already programmed four (4) valid Sen-
try Keys.
²If the ignition switch is turned to the OFF posi-
tion for more than about fifty (50) seconds.
NOTE: If you attempt to start the vehicle while in
ªCustomer Learnº mode (LED flashing), the vehicle
will behave as though an invalid key is being used
(i.e. the engine will stall after two (2) seconds of
running). No faults will be logged.
NOTE: Once a Sentry Key has been programmed to
a particular vehicle, it cannot be used on any other
vehicle.
VTSS/SKIS INDICATOR LAMP
DESCRIPTION
The Sentry Key Remote Entry System (SKREES)
uses an indicator light to convey information on the
status of the system to the customer. This light is
shared with the Vehicle Theft Security System
(VTSS). The light is located in the Mechanical
Instrument Cluster (MIC). The VTSS status is con-
trolled by the Body Control Module (BCM), via Pro-
grammable Communication Interface (PCI) data bus
communication with the MIC, based upon messages
it receives from the Sentry Key Remote Entry Mod-
ule (SKREEM) on the PCI data bus.
RSVEHICLE THEFT SECURITY8Q-7
TRANSPONDER KEY (Continued)

OPERATION
The Mechanical Instrument Cluster (MIC) per-
forms a four second bulb check via PCI communica-
tion with the Sentry Key Remote Entry Module
(SKREEM). After the bulb check, the lamp is con-
trolled according to SKREEM messages. Then, the
SKREEM sends messages to the BCM to operate the
light based upon the results of the Sentry Key
Remote Entry System (SKREES) self tests. The light
may be actuated in two possible ways, flashing or on
solid. If the light comes on and stays on solid after a
power-up test, this indicates that the SKREEM has
detected a system malfunction. If the SKREEM
detects an invalid key when the ignition switch is
moved to the ON position, it sends a message on thePCI bus to the MIC, to flash the light. The SKREEM
can also send a message to flash the light and gen-
erate a single audible chime at the same time. These
two events occurring simultaneously indicate that
the SKIS has been placed into the9Customer Learn9
mode (Refer to 8 - ELECTRICAL/VEHICLE THEFT
SECURITY/TRANSPONDER KEY - STANDARD
PROCEDURE). If the light comes on and stays on
after the power-up test, diagnosis of the SKREES
should be performed using a DRBIIItscan tool and
the appropriate Body Diagnostic Procedures informa-
tion. The light is a Light Emitting Diode (LED) and
is not a serviceable component.
8Q - 8 VEHICLE THEFT SECURITYRS
VTSS/SKIS INDICATOR LAMP (Continued)

brushes inside the motor. The current flow is con-
trolled by the multi-function switch. The high speed/
low speed relays are located in the IPM. The speed
sensitive intermittent wiper is controlled by the Body
Control Module (BCM). The intermittent mode, with
the vehicle traveling greater than 10.4 mph, has a
range of 0.5 to 18 seconds. With the vehicle traveling
less than 10.4 mph, the time delay doubles to a
range of 1 to 36 seconds. The wiper arms will park at
the base of the windshield just above the cowl cover
after the wiper switch is turned OFF.
The windshield wiper motor and linkage is located
in an integral wiper unit at the rear of the engine
compartment. The wiper unit must be removed to
gain access to the wiper motor.
REAR WIPER/WASHER SYSTEM
When rear wiper operation is required, the BCM
will provide ignition ON voltage to the rear wiper
motor (Export and ATC equipped vehicles only).
When the wiper switch is turned OFF, the BCM pro-
vides circuit ground to operate the motor until the
wipe cycle is complete and the wiper arm returns to
the base of the rear window.
Switch only offers an intermittent rear wiper
mode. The wiper motor will cycle every 7 seconds.
The intermittent delay time is also adjusted based
upon vehicle speed. With the vehicle traveling
greater than 50 mph, the cycle changes to every 5
seconds.
When rear washer is requested by depressing and
holding down the switch, the BCM then provides a
ground for the rear washer motor. Until the switch is
released, the motor will be in a continuous wipe
mode, then return to an intermittent wipe mode.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - FRONT WIPER
SYSTEM
The windshield wiper system operates in several
modes:
²Low and high speed normal wipe
²Speed sensitive intermittent wipe
²Wipe after wash
²Park (switch OFF)
The windshield wiper circuits are continuously
monitored and controlled by the Body Control Mod-
ule (BCM). If a problem occurs in the electronic com-
ponents, wiring, switch (except integral motor park
switch) and wiper motor a Diagnostic Trouble Code
(DTC) will be stored in the BCM memory. DTC's can
be retrieved using a DRB IIItscan tool. Refer to the
proper Body Diagnostic Procedures manual for DTC
descriptions and retrieval information.The windshield wiper park switch and circuit is
monitored by the BCM. The park switch and circuit
can be tested using the Wiper System Diagnosis
table.
DIAGNOSIS AND TESTING - FRONT
WIPER/WASHER SWITCH
(1) Remove the multi-function switch (Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
MULTI-FUNCTION SWITCH - REMOVAL).
(2) Using an ohmmeter check resistance readings
between switch pins. Refer to the WIPER/WASHER
SWITCH RESISTANCE table.
WIPER/WASHER SWITCH RESISTANCE
SWITCH POSITION RESISTANCE BETWEEN
OFF 1 AND 2 = 23.9KV 5%
DELAY POSITION
1ST 1 AND 2 = 7.9KV 5%
2ND 1 AND 2 = 4.6KV 5%
3RD 1 AND 2 = 2.9KV 5%
4TH 1 AND 2 = 1.9KV 5%
5TH 1 AND 2 = 1.3KV 5%
LOW 1 AND 2 = 670V 5%
HIGH 1 AND2=240V 5%
WASH 1 AND 4 = 5.9KV 5%
DIAGNOSIS AND TESTING - FAILED PARK
SWITCH
If the wiper park switch has failed, the windshield
wipers will operate as follows:
²SWITCH OFF- Wipers stop in current location
regardless of the park signal.
²INTERMITTENT MODE- Wipers operate con-
tinuously or at low speed for one or more extra
wipes.
²LOW SPEED- Wipers operate at low speed.
²HIGH SPEED- Wipers operate at high speed.
²WIPE AFTER WASH- Wipers operate at low
speed in any mode setting. Wipers operate only while
the wash button is depressed with switch in the OFF
mode and wipers stop in mid-cycle when button is
released.
The windshield wiper park switch and circuit is
monitored by the BCM. The park switch and circuit
can be tested using the WIPER SYSTEM DIAGNO-
SIS table.
8R - 2 WIPERS/WASHERSRS
WIPERS/WASHERS (Continued)

REAR WIPER MOTOR
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove rear wiper arm. (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/REAR WIPER ARM -
REMOVAL) in this section.
(3) Open liftgate.
(4) Remove liftgate trim panel. (Refer to 23 -
BODY/DECKLID/HATCH/LIFTGATE/TAILGATE/
TRIM PANEL - REMOVAL).
(5) Disconnect wire connector from rear wiper
motor.
(6) Remove screws holding rear wiper motor to lift-
gate (Fig. 3).
(7) Remove wiper motor from liftgate.
INSTALLATION
(1) Position the wiper motor in the liftgate.
(2) Install the retaining screws.
(3) Connect the wire harness connector.
(4) Install the liftgate trim panel. (Refer to 23 -
BODY/DECKLID/HATCH/LIFTGATE/TAILGATE/
TRIM PANEL - INSTALLATION).
(5) Connect wire connector to rear wiper motor.
(6) Install the screws holding rear wiper motor to
liftgate (Fig. 3).
(7) Install the wiper motor to the liftgate (Fig. 3).
(8) Close the liftgate.
(9) Install the wiper arm. (Refer to 8 - ELECTRI-
CAL/WIPERS/WASHERS/REAR WIPER ARM -
INSTALLATION) in this section.
(10) Connect the battery negative cable.
REAR WIPER/WASHER
SWITCH
DESCRIPTION
On Automatic Temperature Control (ATC) vehicles
only, the rear window wiper/washer switches are
located on the center bezel with the hazard and
heated seat switches (Fig. 4). They are not service-
able separately from the hazard and heated seat
switches. If defective, the entire switch assembly
must be replaced.
On Manual Temperature Control (MTC) vehicles
only, the rear window wiper/washer switch is located
on the HVAC control head (Fig. 5) attached to the
center bezel. They are not serviceable separately
from the control head. If found faulty, the entire
MTC head must be replaced.
OPERATION
When rear wiper operation is required, the BCM
will provide ignition ON voltage to the rear wiper
motor. When the wiper switch is turned OFF, the
BCM provides circuit ground to operate the motor
until the wipe cycle is complete and the wiper arm
returns to the base of the rear window.
The rear wiper/washer switch only offers an inter-
mittent rear wiper mode. The wiper motor will cycle
every 7 seconds. The intermittent delay time is also
adjusted based upon vehicle speed. With the vehicle
traveling greater than 50 mph, the cycle changes to
every 5 seconds.
Fig. 3 REAR WINDOW WIPER MOTOR
1 - REAR WINDOW
2 - REAR WIPER MOTOR
3 - CHMSL
4 - WELL NUTS
Fig. 4 INSTRUMENT PANEL CENTER BEZEL
1 - TRIM BEZEL
2 - IN CAR TEMPERATURE SENSOR
3 - A/C REQUEST SWITCH
4 - REAR WINDOW DEFOGGER/HEATED MIRRORS SWITCH
COMBO
5 - FRONT WINDOW DEFROSTER MODE SELECTOR
RSWIPERS/WASHERS8R-11

DESCRIPTION - CIRCUIT FUNCTIONS
All circuits in the diagrams use an alpha/numeric
code to identify the wire and it's function. To identify
which circuit code applies to a system, refer to the
Circuit Identification Code Chart. This chart shows
the main circuits only and does not show the second-
ary codes that may apply to some models.
CIRCUIT IDENTIFICATION CODE CHART
CIRCUIT FUNCTION
A BATTERY FEED
B BRAKE CONTROLS
C CLIMATE CONTROLS
D DIAGNOSTIC CIRCUITS
E DIMMING ILLUMINATION
CIRCUITS
F FUSED CIRCUITS
G MONITORING CIRCUITS
(GAUGES)
H OPEN
I NOT USED
J OPEN
K POWERTRAIN CONTROL
MODULE
L EXTERIOR LIGHTING
M INTERIOR LIGHTING
N NOT USED
O NOT USED
P POWER OPTION (BATTERY
FEED)
Q POWER OPTIONS (IGNITION
FEED)
R PASSIVE RESTRAINT
S SUSPENSION/STEERING
T TRANSMISSION/TRANSAXLE/
TRANSFER CASE
U OPEN
V SPEED CONTROL, WIPER/
WASHER
W OPEN
X AUDIO SYSTEMS
Y OPEN
Z GROUNDS
DESCRIPTION - SECTION IDENTIFICATION AND
INFORMATION
The wiring diagrams are grouped into individual
sections. If a component is most likely found in a par-
ticular group, it will be shown complete (all wires,
connectors, and pins) within that group. For exam-
ple, the Auto Shutdown Relay is most likely to be
found in Group 30, so it is shown there complete. It
can, however, be shown partially in another group if
it contains some associated wiring.
Splice diagrams in Section 8W-70 show the entire
splice and provide references to other sections the
splices serves. Section 8W-70 only contains splice dia-
grams that are not shown in their entirety some-
where else in the wiring diagrams.
Section 8W-80 shows each connector and the cir-
cuits involved with that connector. The connectors
are identified using the name/number on the dia-
gram pages.
WIRING SECTION CHART
GROUP TOPIC
8W-01 thru
8W-09General information and Diagram
Overview
8W-10 thru
8W-19Main Sources of Power and
Vehicle Grounding
8W-20 thru
8W-29Starting and Charging
8W-30 thru
8W-39Powertrain/Drivetrain Systems
8W-40 thru
8W-49Body Electrical items and A/C
8W-50 thru
8W-59Exterior Lighting, Wipers and
Trailer Tow
8W-60 thru
8W-69Power Accessories
8W-70 Splice Information
8W-80 Connector Pin Outs
8W-91 Connector, Ground and Splice
Locations
8W - 01 - 6 8W-01 WIRING DIAGRAM INFORMATIONRS
WIRING DIAGRAM INFORMATION (Continued)

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) whenthe 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-
tion. The IOD fuse is a 20 ampere blade-type mini
fuse and, when removed, it is stored in a fuse cavity
adjacent to the washer fuse within the IPM.
OPERATION
The term ignition-off draw identifies a normal condi-
tion where power is being drained from the battery with
the ignition switch in the Off position. The IOD fuse
feeds the memory and sleep mode functions for some of
the electronic modules in the vehicle as well as various
other accessories that require battery current when the
ignition switch is in the Off position, including the
clock. The only reason the IOD fuse is removed is to
reduce the normal IOD of the vehicle electrical system
during new vehicle transportation and pre-delivery stor-
age to reduce battery depletion, while still allowing
vehicle operation so that the vehicle can be loaded,
unloaded and moved as needed by both vehicle trans-
portation company and dealer personnel.
The IOD fuse is removed from the IPM fuse cavity
when the vehicle is shipped from the assembly plant.
Dealer personnel must install the IOD fuse when the
vehicle is being prepared for delivery in order to
restore full electrical system operation. Once the
vehicle is prepared for delivery, the IOD function of
this fuse becomes transparent and the fuse that has
been assigned the IOD designation becomes only
another Fused B(+) circuit fuse. The IOD fuse serves
no useful purpose to the dealer technician in the ser-
vice or diagnosis of any vehicle system or condition,
other than the same purpose as that of any other
standard circuit protection device.
The IOD fuse can be used by the vehicle owner as
a convenient means of reducing battery depletion
when a vehicle is to be stored for periods not to
exceed about thirty days. However, it must be
remembered that removing the IOD fuse will not
eliminate IOD, but only reduce this normal condition.
If a vehicle will be stored for more than about thirty
days, the battery negative cable should be discon-
nected to eliminate normal IOD; and, the battery
should be tested and recharged at regular intervals
during the vehicle storage period to prevent the bat-
tery from becoming discharged or damaged. Refer to
Battery Systemfor additional service information.
Fig. 3 DISCONNECTING IPM
1 - INTEGRATED POWER MODULE FUSE & RELAY CENTER
RS8W-97 POWER DISTRIBUTION SYSTEM8W-97-3
INTEGRATED POWER MODULE (Continued)

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
14 - 18 FUEL INJECTIONRS