battery CHRYSLER VOYAGER 2001 Service Manual

(2) Reconnect the 24±way electrical and the pump/
motor connector. (Fig. 2)
(3) Install the battery tray (Refer to 8 - ELECTRI-
CAL/BATTERY SYSTEM/TRAY - INSTALLATION).
(4) Install the screw securing the coolant filler
neck to the battery tray.
(5) Reconnect the vacuum hose to the coolant tank
built into the battery tray.
(6) Install the battery (Refer to 8 - ELECTRICAL/
BATTERY SYSTEM/BATTERY - INSTALLATION).
(7) Reconnect the battery cables.
(8) Connect a DRBIIItto the vehicle and initialize
the system.
DATA LINK CONNECTOR
DESCRIPTION
The data link connector is located inside the vehi-
cle, below instrument panel next to the center col-
umn (Fig. 4) .
OPERATION
The data link connector (diagnostic connector)
links the DRB scan tool with the Powertrain Control
Module (PCM). Refer to On-Board Diagnostics in the
General Diagnosis section of this group.
FRONT CONTROL MODULE
DESCRIPTION
The Front Control Module (FCM) is a micro con-
troller based module located in the engine compart-
ment (Fig. 5). This FCM mates to the power
distribution center to form the Intelligent PowerModule (IPM). The intelligent power module connects
directly to the battery and provides the primary
means of circuit protection and power distribution for
all vehicle electrical systems. The front control mod-
ule controls power to some of these vehicle systems
electrical and electromechanical loads based on
inputs received from hard wired switch inputs and
data received on the PCI bus circuit (J1850).
For information on theIntelligent Power Mod-
ule(IPM)Refer to the Power Distribution Sec-
tionof the service manual.
OPERATION
As messages are sent over the PCI bus circuit, the
front control module reads these messages and con-
trols power to some of the vehicles electrical systems
by completing the circuit to ground (low side driver)
or completing the circuit to 12 volt power (high side
driver). The following functions arecontrolledby
the Front Control Module:
²Occupant Restraint Controller Voltage
²Headlamp Power with Voltage Regulation
²Side Airbag Voltage
²Electronic Transaxle (Gasoline engine Vehicles)
²Brake Transmission Shift Interlock Functions
(BTSI)
²Front Windshield Wiper ªONº Relay Actuation
²Front Windshield Wiper ªHIº & ªLOº Relay
Actuation
²Front Washer Motor
²Rear Washer Motor
Fig. 4 DATA LINK CONNECTOR
Fig. 5 FRONT CONTROL MODULE
1 - FRONT CONTROL MODULE
RSELECTRONIC CONTROL MODULES8E-5
CONTROLLER ANTILOCK BRAKE (Continued)

²Front Fog Lamp Relay Actuation
²Front and Rear Blower Motor Relay Actuation
²Accessory Relay Actuation
²Electronic Back Light (EBL) Rear Defogger
²Horn Relay Actuation
²Park Lamp Relay Actuation
²Name Brand Speaker (NBS) Relay Actuation
²Headlamp Washer Relay Actuation
²Diesel Cabin Heater (Diesel Engine Vehicles)
The following inputs areReceived/Monitoredby
the Front Control Module:
²B+ Connection Detection
²Ambient Temperature Sensing
²Right/Left Park Lamp Outage
²Ignition Switch Start Only
²Ignition Switch Run and Start Only
²Washer Fluid Level
²Windshield Wiper Park
²Brake Fluid Level
²Back-Up switch
²Stop Lamp Sense
²Engine Crank Signal (Diesel Engine Vehicles)
²Horn Input
DIAGNOSIS AND TESTING - FRONT CONTROL
MODULE
The front control module is a printed circuit board
based module with a on-board micro-processor. The
front control module interfaces with other electronic
modules in the vehicle via the Programmable Com-
munications Interface (PCI) data bus (J1850). In
order to obtain conclusive testing the Programmable
Communications Interface (PCI) data bus network
and all of the electronic modules that provide inputs
to, or receive outputs from the front control module
must be checked. All PCI (J1850) communication
faults must be resolved prior to further diagnosing
any front control module related issues.
The front control module was designed to be diag-
nosed with an appropriate diagnostic scan tool, such
as the DRB IIIt. The most reliable, efficient, and
accurate means to diagnose the front control module
requires the use of a DRB IIItscan tool and the
proper Body Diagnostic Procedures manual.
Before any testing of the front control module is
attempted, the battery should be fully charged and
all wire harness and ground connections inspected
around the affected areas on the vehicle.
REMOVAL
(1) Disconnect the positive and negative battery
cables from the battery.
(2) Remove the battery from the vehicle. Refer to
the procedure in Battery Systems.(3) Using a long flat-pladed screwdriver, gently
twist the Intelligent Power Module (IPM) retaining
clip outboard to free the intelligent power module
from its mounting bracket (Fig. 6). Rotate intelligent
power module upward to access the Front Control
Module (FCM) retaining screws.
(4) Remove the front control module retaining
screws.
(5) Using both hands, pull the front control module
straight from the intelligent power module assembly
to disconnect the 49-way electrical connector (Fig. 7)
and remove the front control module from the vehi-
cle.
INSTALLATION
(1) Install the front control module in the intelli-
gent power module assembly by pushing the 49-way
electrical connector straight in (Fig. 7).
(2) Install the front control module retaining
screws. Torque the screws to 7 in. lbs.
(3) Rotate the intelligent power module assembly
downward to secure in mounting bracket.
(4) Install the battery in the vehicle. Refer to the
procedure in Battery Systems.
(5) Connect the positive and negative battery
cables.
NOTE: If the vehicle is not equipped with Name
Brand Speakers (NBS, Infinity) or Headlamp Wash-
ers the DRB IIITmust be used to Disable the appro-
priate relays in the Intelligent Power Module
Assembly.
Fig. 6 REMOVING INTELLIGENT POWER MODULE
8E - 6 ELECTRONIC CONTROL MODULESRS
FRONT CONTROL MODULE (Continued)

MEMORY HEATED SEAT/
MIRROR MODULE
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Move seat to full forward position.
(3) Working under the seat, disconnect the module
wire harness connectors.
(4) Remove the module retaining screws.
(5) Remove the module from under the seat.
INSTALLATION
(1) Install the module under the seat.
(2) Install the module retaining screws.
(3) Working under the seat, connect the module
wire harness connectors.
(4) Connect and isolate the negative battery cable.
POWER LIFTGATE MODULE
DESCRIPTION
Vehicles equipped with a power liftgate (PLG) uti-
lize a PLG control module. This module is located on
the vehicles left side D-pillar just below the motor
assembly (Fig. 8) and contains a microprocessor,
which is used to communicate to the vehicles body
control module. The PLG control module receives and
monitors logic inputs from all the PLG systemswitches except for the outside handle switch. This
module also contains the software technology to
detect liftgate obstructions and stop and / or reverse
the door accordingly.
OPERATION
The PLG control module contains the electronic cir-
cuitry and software used to control the sequence of
events for the PLG system. This module comunicates
on the PCI bus circuit with the vehicles body control
module to monitor many different inputs and outputs
such as door lock status, transmission gear selector
position and vehicle speed. Refer to PLG system
operation for more information.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove left D-pillar trim panel from the vehi-
cle. Refer to Body for the procedure.
(3) Disconnect the wire harness connections from
the PLG motor assembly (Fig. 9).
(4) Remove the screw holding the PLG control
module to the D-pillar (Fig. 9).
(5) Remove the PLG control module from the vehi-
cle.
Fig. 7 FRONT CONTROL MODULE
1 - POWER LIFTGATE CONTROL MODULE
Fig. 8 LIFTGATE CONTROL MODULE
1 - POWER LIFTGATE CONTROL MODULE
2 - MODULE RETAINING SCREWS
3 - D-PILLAR
4 - POWER LIFTGATE MOTOR
5 - MODULE ELECTRICAL CONNECTORS
RSELECTRONIC CONTROL MODULES8E-7
FRONT CONTROL MODULE (Continued)

INSTALLATION
(1) Install the PLG control module on the D-pillar
and install retaining screw. Torque the screw to 14.5
in. lbs.
(2) Connect the wire harness connections on the
PLG control module. Be certain to slide connector
locks to the locked position.
(3) Install the D-pillar trim panel on the vehicle.
Refer to the Body section for the procedure.
(4) Connect the negative battery cable.
(5) Using an appropriate scan tool, check any
erase any PLG control module diagnostic trouble
codes.
(6) Verify PLG system operation. Cycle the PLG
through one complete open and close cycle, this will
allow the PLG control module to relearn its cycle
with the new components.
POWERTRAIN CONTROL
MODULE
DESCRIPTION
The Powertrain Control Module (PCM) is a digital
computer containing a microprocessor (Fig. 10). The
PCM receives input signals from various switchesand sensors referred to as Powertrain Control Mod-
ule Inputs. Based on these inputs, the PCM adjusts
various engine and vehicle operations through
devices referred to as Powertrain Control Module
Outputs.
NOTE: PCM Inputs:
²Air Conditioning Pressure Transducer
²ASD Relay
²Battery Voltage
²Brake Switch
²Camshaft Position Sensor
²Crankshaft Position Sensor
²Distance Sensor (from transmission control mod-
ule)
²EGR Position Feedback
²Engine Coolant Temperature Sensor
²Heated Oxygen Sensors
²Ignition sense
²Intake Air Temperature Sensor
²Knock Sensor
²Leak Detection Pump Feedback
²Manifold Absolute Pressure (MAP) Sensor
²Park/Neutral (from transmission control module)
²PCI Bus
²Power Steering Pressure Switch
²Proportional Purge Sense
²SCI Receive
²Speed Control
Fig. 9 LIFTGATE CONTROL MODULE
1 - POWER LIFTGATE CONTROL MODULE
2 - MODULE RETAINING SCREWS
3 - D-PILLAR
4 - POWER LIFTGATE MOTOR
5 - MODULE ELECTRICAL CONNECTORS
Fig. 10 Powertrain Control Module (PCM)
1 - Battery
2 - Power Distribution Center
3 - Powertrain Control Module
8E - 8 ELECTRONIC CONTROL MODULESRS
POWER LIFTGATE MODULE (Continued)

²Throttle Position Sensor
²Torque Management Input (From TCM)
²Transaxle Control Module (TCM)
²Transaxle Gear Engagement (From TCM)
²Vehicle Speed (from transmission control mod-
ule)
NOTE: PCM Outputs:
²Air Conditioning Clutch Relay
²Automatic Shut Down (ASD) and Fuel Pump
Relays
²Data Link Connector (PCI and SCI Transmit)
²Double Start Override
²EGR Solenoid
²Fuel Injectors
²Generator Field
²High Speed Fan Relay
²Idle Air Control Motor
²Ignition Coils
²Leak Detection Pump
²Low Speed Fan Relay
²MTV Actuator
²Proportional Purge Solenoid
²SRV Valve
²Speed Control Relay
²Speed Control Vent Relay
²Speed Control Vacuum Relay
²8 Volt Output
²5 Volt Output
Based on inputs it receives, the powertrain control
module (PCM) adjusts fuel injector pulse width, idle
speed, ignition timing, and canister purge operation.
The PCM regulates the cooling fans, air conditioning
and speed control systems. The PCM changes gener-
ator charge rate by adjusting the generator field.
The PCM adjusts injector pulse width (air-fuel
ratio) based on the following inputs.
²Battery Voltage
²Intake Air Temperature Sensor
²Engine Coolant Temperature
²Engine Speed (crankshaft position sensor)
²Exhaust Gas Oxygen Content (heated oxygen
sensors)
²Manifold Absolute Pressure
²Throttle Position
The PCM adjusts engine idle speed through the
idle air control motor based on the following inputs.
²Brake Switch
²Engine Coolant Temperature
²Engine Speed (crankshaft position sensor)
²Park/Neutral (transmission gear selection)
²Transaxle Gear Engagement
²Throttle Position
²Vehicle Speed (from Transmission Control Mod-
ule)The PCM adjusts ignition timing based on the fol-
lowing inputs.
²Intake Air Temperature
²Engine Coolant Temperature
²Engine Speed (crankshaft position sensor)
²Knock Sensor
²Manifold Absolute Pressure
²Park/Neutral (transmission gear selection)
²Transaxle Gear Engagement
²Throttle Position
The automatic shut down (ASD) and fuel pump
relays are mounted externally, but turned on and off
by the powertrain control module through the same
circuit.
The camshaft and crankshaft signals are sent to
the powertrain control module. If the PCM does not
receive both signals within approximately one second
of engine cranking, it deactivates the ASD and fuel
pump relays. When these relays are deactivated,
power is shut off to the fuel injectors, ignition coils,
fuel pump and the heating element in each oxygen
sensor.
The PCM contains a voltage converter that
changes battery voltage to a regulated 8.0 volts. The
8.0 volts power the camshaft position sensor, crank-
shaft position sensor and vehicle speed sensor. The
PCM also provides a 5.0 volts supply for the engine
coolant temperature sensor, intake air temperature
sensor, manifold absolute pressure sensor and throt-
tle position sensor.
The PCM engine control strategy prevents reduced
idle speeds until after the engine operates for 320 km
(200 miles). If the PCM is replaced after 320 km (200
miles) of usage, update the mileage in new PCM. Use
the DRB scan tool to change the mileage in the PCM.
Refer to the appropriate Powertrain Diagnostic Man-
ual and the DRB scan tool.
DIAGNOSTIC TROUBLE CODE
DESCRIPTION
A Diagnostic Trouble Code (DTC) indicates the
PCM has recognized an abnormal condition in the
system.
Remember that DTC's are the results of a sys-
tem or circuit failure, but do not directly iden-
tify the failed component or components.
NOTE: For a list of DTC's, refer to the charts in this
section.
RSELECTRONIC CONTROL MODULES8E-9
POWERTRAIN CONTROL MODULE (Continued)

(M) Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code was recorded.
(G) Generator Lamp Illuminated
GENERIC SCAN
TOOL CODEDRB SCAN TOOL DISPLAY DESCRIPTION OF DIAGNOSTIC TROUBLE CODE
P1292 CNG Pressure Sensor Voltage Too
HighCompressed natural gas pressure sensor reading above
acceptable voltage.
P1293 CNG Pressure Sensor Voltage Too
LowCompressed natural gas pressure sensor reading below
acceptable voltage.
P1294 (M) Target Idle Not Reached Target RPM not achieved during drive idle condition.
Possible vacuum leak or IAC (AIS) lost steps.
P1295 No 5 Volts to TP Sensor Loss of a 5 volt feed to the Throttle Position Sensor has
been detected.
P1296 No 5 Volts to MAP Sensor Loss of a 5 volt feed to the MAP Sensor has been detected.
P1297 (M) No Change in MAP From Start To
RunNo difference is recognized between the MAP reading at
engine idle and the stored barometric pressure reading.
P1298 Lean Operation at Wide Open
ThrottleA prolonged lean condition is detected during Wide Open
Throttle.
P1299 (M) Vacuum Leak Found (IAC Fully
Seated)MAP Sensor signal does not correlate to Throttle Position
Sensor signal. Possible vacuum leak.
P1388 Auto Shutdown Relay Control Circuit An open or shorted condition detected in the ASD or CNG
shutoff relay control ckt.
P1389 No ASD Relay Output Voltage At
PCMNo Z1 or Z2 voltage sensed when the auto shutdown relay
is energized.
P1390 (M) Timing Belt Skipped 1 Tooth or More Relationship between Cam and Crank signals not correct.
P1391 (M) Intermittent Loss of CMP or CKP Loss of the Cam Position Sensor or Crank Position sensor
has occurred. For PL 2.0L
P1398 (M) Mis-Fire Adaptive Numerator at Limit PCM is unable to learn the Crank Sensor's signal in
preparation for Misfire Diagnostics. Probable defective Crank
Sensor.
P1399 Wait To Start Lamp Cicuit An open or shorted condition detected in the Wait to Start
Lamp circuit.
P1403 No 5 Volts to EGR Sensor Loss of 5v feed to the EGR position sensor.
P1476 Too Little Secondary Air Insufficient flow of secondary air injection detected during
aspirator test.(was P0411)
P1477 Too Much Secondary Air Excessive flow of secondary air injection detected during
aspirator test (was P0411).
P1478 (M) Battery Temp Sensor Volts Out of
LimitInternal temperature sensor input voltage out of an
acceptable range.
P1479 Transmission Fan Relay Circuit An open or shorted condition detected in the transmission
fan relay circuit.
P1480 PCV Solenoid Circuit An open or shorted condition detected in the PCV solenoid
circuit.
P1482 Catalyst Temperature Sensor Circuit
Shorted LowCatalyst temperature sensor circuit shorted low.
P1483 Catalyst Temperature Sensor Circuit
Shorted High.Catalyst temperature sensor circuit shorted high.
P1484 Catalytic Converter Overheat
DetectedA catalyst overheat condition has been detected by the
catalyst temperature sensor.
8E - 16 ELECTRONIC CONTROL MODULESRS
POWERTRAIN CONTROL MODULE (Continued)

(M) Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code was recorded.
(G) Generator Lamp Illuminated
GENERIC SCAN
TOOL CODEDRB SCAN TOOL DISPLAY DESCRIPTION OF DIAGNOSTIC TROUBLE CODE
P1485 Air Injection Solenoid Circuit An open or shorted condition detected in the air assist
solenoid circuit.
P1486 (M) Evap Leak Monitor Pinched Hose
FoundLDP has detected a pinched hose in the evaporative hose
system.
P1487 Hi Speed Rad Fan CTRL Relay
CircuitAn open or shorted condition detected in the control circuit
of the #2 high speed radiator fan control relay.
P1488 Auxiliary 5 Volt Supply Output Too
LowAuxiliary 5 volt sensor feed is sensed to be below an
acceptable limit.
P1489 (M) High Speed Fan CTRL Relay Circuit An open or shorted condition detected in the control circuit
of the high speed radiator fan control relay.
P1490 (M) Low Speed Fan CTRL Relay Circuit An open or shorted condition detected in control circuit of
the low speed radiator fan control relay.
P1491 Rad Fan Control Relay Circuit An open or shorted condition detected in the radiator fan
control relay control circuit. This includes PWM solid state
relays.
P1492 (M,G) Ambient/Batt Temp Sen Volts Too
HighExternal temperature sensor input above acceptable voltage.
P1493 (M,G) Ambient/Batt Temp Sen Volts Too
LowExternal temperature sensor input below acceptable voltage.
P1494 (M) Leak Detection Pump Sw or
Mechanical FaultIncorrect input state detected for the Leak Detection Pump
(LDP) pressure switch.
P1495 (M) Leak Detection Pump Solenoid
CircuitAn open or shorted condition detected in the Leak Detection
Pump (LDP) solenoid circuit.
P1496 (M) 5 Volt Supply, Output Too Low 5 volt sensor feed is sensed to be below an acceptable limit.
( < 4v for 4 sec ).
P1498 High Speed Rad Fan Ground CTRL
Rly CircuitAn open or shorted condition detected in the control circuit
of the #3 high speed radiator fan control relay.
P1594 (G) Charging System Voltage Too High Battery voltage sense input above target charging voltage
during engine operation.
P1595 Speed Control Solenoid Circuits An open or shorted condition detected in either of the speed
control vacuum or vent solenoid control circuits.
P1596 Speed Control Switch Always High Speed control switch input above maximum acceptable
voltage.
P1597 Speed Control Switch Always Low Speed control switch input below minimum acceptable
voltage.
P1598 A/C Pressure Sensor Volts Too High A/C pressure sensor input above maximum acceptable
voltage.
P1599 A/C Pressure Sensor Volts Too Low A/C pressure sensor input below minimum acceptable
voltage.
P1602 PCM not Programmed
P1680 Clutch Released Switch Circuit
P1681 No I/P Cluster CCD/J1850
Messages ReceivedNo CCD/J1850 messages received from the cluster control
module.
RSELECTRONIC CONTROL MODULES8E-17
POWERTRAIN CONTROL MODULE (Continued)

(M) Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code was recorded.
(G) Generator Lamp Illuminated
GENERIC SCAN
TOOL CODEDRB SCAN TOOL DISPLAY DESCRIPTION OF DIAGNOSTIC TROUBLE CODE
P1682 (G) Charging System Voltage Too Low Battery voltage sense input below target charging voltage
during engine operation and no significant change in voltage
detected during active test of generator output circuit.
P1683 SPD CTRL PWR Relay; or S/C 12v
Driver CKTAn open or shorted condition detected in the speed control
servo power control circuit. (SBECII: ext relay).
P1684 Battery Loss In The Last 50 Starts The battery has been disconnected within the last 50 starts.
P1685 Skim Invalid Key The engine controler has received an invalid key from the
SKIM.
P1686 No SKIM BUS Messages Received No CCD/J1850 messages received from the Smart Key
Immobilizer Module (SKIM).
P1687 No MIC BUS Message No CCD/J1850 messages received from the Mechanical
Instrument Cluster (MIC) module.
P1693 DTC Detected in Companion Module A fault has been generated in the companion engine control
module.
P1694 Fault In Companion Module No CCD/J1850 messages received from the powertrain
control module-Aisin transmission.
P1695 No CCD/J1850 Message From Body
Control ModuleNo CCD/J1850 messages received from the body control
module.
P1696 (M) PCM Failure EEPROM Write Denied Unsuccessful attempt to write to an EEPROM location by the
control module.
P1697 (M) PCM Failure SRI Mile Not Stored Unsuccessful attempt to update Service Reminder Indicator
(SRI or EMR) mileage in the control module EEPROM.
P1698 (M) No CCD/J1850 Message From TCM No CCD/J1850 messages received from the electronic
transmission control module (EATX) or the Aisin transmission
controller.
P1719 Skip Shift Solenoid Circuit An open or shorted condition detected in the transmission
2-3 gear lock-out solenoid control circuit.
P1756 GOV Press Not Equal to Target @
15-20 PSIThe requested pressure and the actual pressure are not
within a tolerance band for the Governor Control System
which is used to regulate governor pressure to control shifts
for 1st, 2nd, and 3rd gear. (Mid Pressure Malfunction)
P1757 GOV Press Not Equal to Target @
15-20 PSIThe requested pressure and the actual pressure are not
within a tolerance band for the Governor Control System
which is used to regulate governor pressure to control shifts
for 1st, 2nd, and 3rd gear (Zero Pressure Malfunction)
P1762 Gov Press Sen Offset Volts Too Low
or HighThe Governor Pressure Sensor input is greater than a
calibration limit or is less than a calibration limit for 3
consecutive park/neutral calibrations.
P1763 Governor Pressure Sensor Volts Too
HiThe Governor Pressure Sensor input is above an acceptable
voltage level.
P1764 Governor Pressure Sensor Volts Too
LowThe Governor Pressure Sensor input is below an acceptable
voltage level.
P1765 Trans 12 Volt Supply Relay CTRL
CircuitAn open or shorted condition is detected in the Transmission
Relay control circuit. This relay supplies power to the TCC>
P1899 (M) P/N Switch Stuck in Park or in Gear Incorrect input state detected for the Park/Neutral switch.
8E - 18 ELECTRONIC CONTROL MODULESRS
POWERTRAIN CONTROL MODULE (Continued)

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
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 and heated oxygen sen-
sors.
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 within664 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:
²Battery voltage
²Engine coolant temperature
²Engine RPM
²Inlet/Intake air temperature (IAT)
²MAP
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:
²Engine coolant temperature
²Manifold Absolute Pressure (MAP)
²Inlet/Intake air temperature (IAT)
²Crankshaft position (engine speed)
²Camshaft position
²Knock 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:
²Inlet/Intake air temperature
²Engine coolant temperature
²Manifold absolute pressure
²Crankshaft position (engine speed)
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.
The PCM performs several diagnostic routines.
They include:
²Oxygen sensor monitor
²Downstream heated oxygen sensor diagnostics
during open loop operation (except for shorted)
8E - 20 ELECTRONIC CONTROL MODULESRS
POWERTRAIN CONTROL MODULE (Continued)

²Fuel system monitor
²EGR monitor
²Purge system monitor
²All inputs monitored for proper voltage range.
²All monitored components (refer to the Emission
section for On-Board Diagnostics).
The PCM compares the upstream and downstream
heated oxygen sensor inputs to measure catalytic
convertor efficiency. If the catalyst efficiency drops
below the minimum acceptable percentage, the PCM
stores a diagnostic trouble code in memory.
During certain idle conditions, the PCM may enter
a variable idle speed strategy. During variable idle
speed strategy the PCM adjusts engine speed based
on the following inputs.
²A/C sense
²Battery voltage
²Battery temperature
²Engine coolant temperature
²Engine run time
²Inlet/Intake air temperature
²Vehicle mileage
ACCELERATION MODE
This is a CLOSED LOOP mode. The PCM recog-
nizes an abrupt increase in Throttle Position sensor
output voltage or MAP sensor output voltage as a
demand for increased engine output and vehicle
acceleration. The PCM increases injector pulse width
in response to increased fuel demand.
DECELERATION MODE
This is a CLOSED LOOP mode. During decelera-
tion the following inputs are received by the PCM:
²A/C sense
²Battery voltage
²Inlet/Intake air temperature
²Engine coolant temperature
²Crankshaft position (engine speed)
²Exhaust gas oxygen content (upstream heated
oxygen sensor)
²Knock sensor
²Manifold absolute pressure
²Throttle position
²IAC motor control changes in response to MAP
sensor feedback
The PCM may receive a closed throttle input from
the Throttle Position Sensor (TPS) when it senses an
abrupt decrease in manifold pressure. This indicates
a hard deceleration. In response, the PCM may
momentarily turn off the injectors. This helps
improve fuel economy, emissions and engine braking.
WIDE-OPEN-THROTTLE MODE
This is an OPEN LOOP mode. During wide-open-
throttle operation, the following inputs are used by
the PCM:
²Inlet/Intake air temperature
²Engine coolant temperature
²Engine speed
²Knock sensor
²Manifold absolute pressure
²Throttle position
When the PCM senses a wide-open-throttle condi-
tion through the Throttle Position Sensor (TPS) it de-
energizes the A/C compressor clutch relay. This
disables the air conditioning system.
The PCM does not monitor the heated oxygen sen-
sor inputs during wide-open-throttle operation except
for downstream heated oxygen sensor and both
shorted diagnostics. The PCM adjusts injector pulse
width to supply a predetermined amount of addi-
tional fuel.
IGNITION SWITCH OFF MODE
When the operator turns the ignition switch to the
OFF position, the following occurs:
²All outputs are turned off, unless 02 Heater
Monitor test is being run. Refer to the Emission sec-
tion for On-Board Diagnostics.
²No inputs are monitored except for the heated
oxygen sensors. The PCM monitors the heating ele-
ments in the oxygen sensors and then shuts down.
STANDARD PROCEDURES - OBTAINING
DIAGNOSTIC TROUBLE CODES
BULB CHECK
Each time the ignition key is turned to the ON
position, the malfunction indicator (check engine)
lamp on the instrument panel should illuminate for
approximately 2 seconds then go out. This is done for
a bulb check. When the key is in the power on, but
engine off position, the MIL will remain illuminated
for regulatory purposes.
OBTAINING DTC'S USING DRB SCAN TOOL
(1) Connect the DRB scan tool to the data link
(diagnostic) connector. This connector is located in
the passenger compartment; at the lower edge of
instrument panel; near the steering column.
(2) Turn the ignition switch on and access the
ªRead Faultº screen.
(3) Record all the DTC's and ªfreeze frameº infor-
mation shown on the DRB scan tool.
RSELECTRONIC CONTROL MODULES8E-21
POWERTRAIN CONTROL MODULE (Continued)