1993 CHEVROLET DYNASTY change time

3.0L MULTI-PORT FUEL INJECTIONÐSYSTEM OPERATION INDEX
page page
Air Conditioning (A/C) Clutch Relay (AA, AG, AJ Body)ÐPCM Output .................... 118
Air Conditioning (A/C) Clutch Relay (AC Body) ÐPCM Output ........................ 118
Air Conditioning Switch Sense (AA, AG, AJ Body)ÐPCM Input ..................... 115
Air Conditioning Switch Sense (AC Body)ÐPCM Input ................................ 115
Auto Shutdown (ASD) Relay and Fuel Pump RelayÐPCM Output .................... 119
Battery VoltageÐPCM Input ............... 115
Brake SwitchÐPCM Input ................. 115
CCD Bus .............................. 113
Data Link ConnectorÐPCM Output .......... 120
Distributor Pick-UpÐPCM Input ............. 115
Duty Cycle Evap Canister Purge Solenoid ÐPCM Output ........................ 119
Engine Coolant Temperature Sensor ÐPCM Input ......................... 115
Fuel InjectorsÐPCM Output ............... 120
Fuel Pressure Regulator .................. 124
Fuel Supply Circuit ...................... 123
General Information ...................... 113 Generator FieldÐPCM Output
.............. 118
Heated Oxygen Sensor (O
2Sensor)
ÐPCM Input ......................... 116
Idle Air Control MotorÐPCM Output ......... 119
Ignition CoilÐPCM Output ................. 121
Malfunction Indicator Lamp (Check Engine Lamp)ÐPCM Output ................... 120
Manifold Absolute Pressure (MAP) Sensor ÐPCM Input ......................... 116
Modes of Operation ...................... 121
Park/Neutral SwitchÐPCM Input ............ 117
Part Throttle Unlock SolenoidÐPCM Output . . . 121
Powertrain Control Module ................. 113
Radiator Fan RelayÐPCM Output ........... 121
Speed Control SolenoidsÐPCM Output ....... 121
Speed ControlÐPCM Input ................ 117
System Diagnosis ....................... 113
TachometerÐPCM Output ................. 121
Throttle Body ........................... 123
Throttle Position Sensor (TPS)ÐPCM Input .... 117
Transaxle Control ModuleÐPCM Output ...... 120
Vehicle Speed and Distance InputÐPCM Input . 118
Vehicle Speed SensorÐPCM Input .......... 118
GENERAL INFORMATION
The 3.0L engine uses a sequential Multi-Port Elec-
tronic Fuel Injection system (Fig. 1). The MPI system
is computer regulated and provides precise air/fuel
ratios for all driving conditions. The MPI system is operated by the powertrain con-
trol module (PCM). The PCM regulates ignition timing, air-fuel ratio,
emission control devices, cooling fan, charging sys-
tem, idle speed and speed control. Various sensors
provide the inputs necessary for the PCM to correctly
operate these systems. In addition to the sensors,
various switches also provide inputs to the PCM. All inputs to the PCM are converted into signals.
The PCM can adapt its programming to meet chang-
ing operating conditions. Fuel is injected into the intake port above the in-
take valve in precise metered amounts through elec-
trically operated injectors. The PCM fires the
injectors in a specific sequence. The PCM maintains
an air fuel ratio of 14.7 parts air to 1 part fuel by
constantly adjusting injector pulse width. Injector
pulse width is the length of time the injector is ener-
gized. 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 the primary inputs that determine injec-
tor pulse width.
SYSTEM DIAGNOSIS
The powertrain control module (PCM) tests many
of its own input and output circuits. If a fault is
found in a major system, the information is stored in
memory. Technicians can display fault information
through the malfunction indicator lamp (instrument
panel Check Engine lamp) or by connecting the
DRBII scan tool. For diagnostic trouble code informa-
tion, refer to the 3.0 Multi-Port Fuel InjectionÐOn-
Board Diagnostics section of this group.
CCD BUS
Various modules exchange information through a
communications port called the CCD Bus. The pow-
ertrain control module (PCM) transmits the malfunc-
tion indicator (instrument panel check engine lamp)
On/Off signal, engine RPM and vehicle load data on
the CCD Bus.
POWERTRAIN CONTROL MODULE
The powertrain control module (PCM) is a digital
computer containing a microprocessor (Fig. 2). The
PCM receives input signals from various switches
and sensors that are referred to as PCM Inputs.
Based on these inputs, the PCM adjusts various en-
gine and vehicle operations through devices referred
to as PCM Outputs. PCM Inputs:
² Air Conditioning Controls
² Battery Voltage
² Brake Switch
Ä FUEL SYSTEMS 14 - 113

(caused by a lean air-fuel mixture), the sensor pro-
duces a low voltage. When there is a lesser amount
present (rich air-fuel mixture) it produces a higher
voltage. By monitoring the oxygen content and con-
verting it to electrical voltage, the sensor acts as a
rich-lean switch. The oxygen sensor is equipped with a heating ele-
ment that keeps the sensor at proper operating tem-
perature during all operating modes. Maintaining
correct sensor temperature at all times allows the
system to enter into Closed Loop operation sooner.
Also, it allow the system to remain in Closed Loop
operation during periods of extended idle. In Closed Loop operation the PCM monitors the O
2sensor input (along with other inputs) and adjusts
the injector pulse width accordingly. During Open
Loop operation the PCM ignores the O
2sensor input.
The PCM adjusts injector pulse width based on pre-
programmed (fixed) values and from inputs of other
sensors.
SPEED CONTROLÐPCM INPUT
The speed control system provides four separate
voltages (inputs) to the PCM. The voltages corre-
spond to the On/Off, Set, and Resume. The speed control ON voltage informs the PCM
that the speed control system has been activated.
The speed control SET voltage informs the PCM that
a fixed vehicle speed has been selected. The speed
control RESUME voltage indicates the previous fixed
speed is requested. The speed control OFF voltage
tells the PCM that the speed control system has de-
activated. Refer to Group 8H for further speed con-
trol information.
PARK/NEUTRAL SWITCHÐPCM INPUT
The park/neutral switch is located on the transaxle
housing (Fig. 8 or Fig. 9). It provides an input to the
PCM indicating whether the automatic transaxle is
in Park or Neutral. This input is used to determine
idle speed (varying with gear selection), fuel injector
pulse width, and ignition timing advance. The park/
neutral switch is sometimes referred to as the neu-
tral safety switch.
THROTTLE POSITION SENSOR (TPS)ÐPCM INPUT
The Throttle Position Sensor (TPS) is mounted on
the throttle body and connected to the throttle blade
shaft (Fig. 10). The TPS is a variable resistor that
provides the PCM with an input signal (voltage) rep-
resenting throttle blade position. As the position of
the throttle blade changes, the resistance of the TPS
changes.
The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
PCM) represents throttle blade position. The TPS
output voltage to the PCM varies from approxi-
mately 0.5 volt at minimum throttle opening (idle) to
3.5 volts at wide open throttle. The wide open throt-
tle input is approximately 3 volts more than the min-
imum throttle opening value. Along with inputs from other sensors, the PCM
uses the TPS input to determine current engine op-
erating conditions. After determining the current op-
erating conditions, the PCM adjust fuel injector pulse
width and ignition timing.
Fig. 8 Park Neutral SwitchÐ3-Speed Automatic Transaxle
Fig. 9 Park Neutral SwitchÐ4-Speed ElectronicAutomatic Transaxle
Fig. 10 Throttle Position Sensor
Ä FUEL SYSTEMS 14 - 117

tially energizes all injectors at the same time. Once
the PCM determines crankshaft position, it begins
energizing the injectors in sequence.Battery voltage is supplied to the injectors through
the ASD relay. The PCM provides the ground path
for the injectors. By switching the ground path on
and off, the PCM adjusts injector pulse width. Pulse
width is the amount of time the injector is energized.
The PCM adjusts injector pulse width based on in-
puts it receives.
IGNITION COILÐPCM OUTPUT
The auto shutdown (ASD) relay provides battery
voltage to the ignition coil. The PCM provides a
ground contact (circuit) for energizing coil. When the
PCM breaks the contact, the energy in the coil pri-
mary transfers to the secondary causing the spark.
The PCM will de-energize the ASD relay if it does
not receive an input from the distributor pick-up. Re-
fer to Auto Shutdown (ASD) Relay/Fuel Pump Re-
layÐPCM Output in this section for relay operation. The ignition coil is mounted on a bracket next to
the air cleaner (Fig. 18).
PART THROTTLE UNLOCK SOLENOIDÐPCM
OUTPUT
Three-speed automatic transaxles use a part throt-
tle unlock solenoid. The PCM controls the lock-up of
the torque convertor through the part throttle unlock
solenoid. The transaxle is locked up only in direct
drive mode. Refer to Group 21 for transaxle informa-
tion.
RADIATOR FAN RELAYÐPCM OUTPUT
The radiator fan is energized by the PCM through
the radiator fan relay. The radiator fan relay is lo-
cated on the drivers side fender well near to the
PCM. The PCM grounds the relay when engine cool-
ant reaches a predetermined temperature or the air
conditioning system turns on. On AA body vehicles, the relay is located next to
the drivers side strut tower (Fig. 13). On AC, AG and AJ body vehicles, the relay is lo-
cated in the power distribution center (Fig. 12 or Fig.
14).
SPEED CONTROL SOLENOIDSÐPCM OUTPUT
The speed control vacuum and vent solenoids are
operated by the PCM. When the PCM supplies a
ground to the vacuum and vent solenoids, the speed
control system opens the throttle blade. When the
PCM supplies a ground only to the vent solenoid, the
throttle blade holds position. When the PCM removes
the ground from both the vacuum and vent solenoids,
the throttle blade closes. The PCM balances the two
solenoids to maintain the set speed. Refer to Group
8H for speed control information.
TACHOMETERÐPCM OUTPUT
The PCM supplies engine RPM to the instrument
panel tachometer through the CCD Bus. The CCD
Bus is a communications port. Various modules use
the CCD Bus to exchange information. Refer to
Group 8E for more information.
MODES OF OPERATION
As input signals to the PCM change, the PCM ad-
justs its response to the output devices. For example,
the PCM must calculate a different injector pulse
width and ignition timing for idle than for wide open
throttle (WOT). There are several different 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 in-
put signals and responds according to preset PCM
programming. Input from the oxygen (O
2) sensor is
not monitored during OPEN LOOP modes. During CLOSED LOOP modes the PCM does mon-
itor the oxygen (O
2) sensor input. This input indi-
cates to the PCM if the injector pulse width results
in an air-fuel ratio of 14.7 parts air to 1 part fuel. By
monitoring the exhaust oxygen content through the
O
2sensor, the PCM can fine tune the injector pulse
width. Fine tuning injector pulse width allows the
PCM to achieve optimum fuel economy combined
with low emissions. The 3.0L sequential MPI system has the following
modes of operation:
² Ignition switch ONÐZero-RPM
² Engine start-up
² Engine warm-up
² Cruise (Idle)
² Acceleration
² Deceleration
² Wide Open Throttle
² Ignition switch OFF
Fig. 18 Ignition Coil
Ä FUEL SYSTEMS 14 - 121

The PCM regulates ignition timing, air-fuel ratio,
emission control devices, cooling fan, charging sys-
tem, idle speed and speed control. Various sensors
provide the inputs necessary for the PCM to correctly
operate these systems. In addition to the sensors,
various switches also provide inputs to the PCM. All inputs to the PCM are converted into signals.
The PCM can adapt its programming to meet chang-
ing operating conditions. Fuel is injected into the intake port above the in-
take valve in precise metered amounts through elec-
trically operated injectors. The PCM fires the
injectors in a specific sequence. The PCM maintains
an air fuel ratio of 14.7 parts air to 1 part fuel by
constantly adjusting injector pulse width. Injector
pulse width is the length of time the injector is ener-
gized. 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 the primary inputs that determine injec-
tor pulse width.
SYSTEM DIAGNOSIS
The PCM tests many of its own input and output
circuits. If a fault is found in a major system, the in-
formation is stored in memory. Technicians can dis-
play fault information through the malfunction
indicator lamp (instrument panel Check Engine
lamp) or by connecting the DRBII scan tool. For di-
agnostic trouble code information, refer to the 3.3L/
3.8L Multi-Point Fuel InjectionÐOn-Board
Diagnostics section of this group.
CCD BUS
Various modules exchange information through a
communications port called the CCD Bus. The pow-
ertrain control module (PCM) transmits engine RPM
and vehicle load information on the CCD Bus.
POWERTRAIN CONTROL MODULE
The powertrain control module (PCM) is a digital
computer containing a microprocessor (Fig. 2). The
PCM receives input signals from various switches
and sensors that are referred to as PCM Inputs.
Based on these inputs, the PCM adjusts various en-
gine and vehicle operations through devices that are
referred to as PCM Outputs. PCM Inputs:
² Air Conditioning Controls
² Battery Voltage
² Brake Switch
² Camshaft Position Sensor
² Crankshaft Position Sensor
² Engine Coolant Temperature Sensor
² Manifold Absolute Pressure (MAP) Sensor
² Oxygen Sensor
² SCI Receive ²
Speed Control System Controls
² Throttle Position Sensor
² Transaxle Park/Neutral Switch (automatic tran-
saxle)
² Vehicle Speed Sensor
PCM Outputs:
² Air Conditioning Clutch Relay
² Generator Field
² Idle Air Control Motor
² Auto Shutdown (ASD) and Fuel Pump Relays
² Canister Purge Solenoid
² Malfunction Indicator Lamp (Check Engine Lamp)
² Data Link Connector
² Electronic EGR Transducer
² Fuel Injectors
² Ignition Coil
² Radiator Fan Relay
² Speed Control Solenoids
² Tachometer Output
Based on inputs it receives, the PCM adjusts the
EGR system, fuel injector pulse width, idle speed, ig-
nition spark advance, ignition coil dwell and canister
purge operation. The PCM regulates the cooling fan,
air conditioning and speed control systems. The PCM
changes generator charge rate by adjusting the gen-
erator field. The PCM adjusts injector pulse width (air-fuel ra-
tio) based on the following inputs.
² battery voltage
² engine coolant temperature
² exhaust gas oxygen content (oxygen sensor)
² engine speed (crankshaft position sensor)
² manifold absolute pressure
² throttle position
The PCM adjusts ignition timing based on the fol-
lowing inputs.
² engine coolant temperature
² engine speed (crankshaft position sensor)
² manifold absolute pressure
² throttle position
Fig. 2 PCM
14 - 146 FUEL SYSTEMS Ä

SPEED CONTROLÐPCM INPUT
The speed control system provides four separate
voltages (inputs) to the PCM. The voltages corre-
spond to the On/Off, Set, and Resume. The speed control ON voltage informs the PCM
that the speed control system has been activated.
The speed control SET voltage informs the PCM that
a fixed vehicle speed has been selected. The speed
control RESUME voltage indicates the previous fixed
speed is requested. The speed control OFF voltage
tells the PCM that the speed control system has been
deactivated. Refer to Group 8H for further speed con-
trol information.
TRANSAXLE PARK/NEUTRAL SWITCHÐPCM
INPUT
The park/neutral switch is located on the transaxle
housing (Fig. 12). It provides an input to the PCM
indicating whether the automatic transaxle is in
Park or Neutral. This input is used to determine idle
speed (varying with gear selection) and ignition tim-
ing advance. The park neutral switch is sometimes
referred to as the neutral safety switch.
THROTTLE POSITION SENSOR (TPS)ÐPCM INPUT
The Throttle Position Sensor (TPS) is mounted on
the throttle body and connected to the throttle blade
shaft (Fig. 13). The TPS is a variable resistor that
provides the PCM with an input signal (voltage). The
signal represents throttle blade position. As the posi-
tion of the throttle blade changes, the resistance of
the TPS changes. The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
PCM) represents the throttle blade position. The TPS
output voltage to the PCM varies from approxi-
mately 0.5 volt at minimum throttle opening (idle) to
3.5 volts at wide open throttle. Along with inputs
from other sensors, the PCM uses the TPS input to
determine current engine operating conditions. The PCM also adjust fuel injector pulse width and igni-
tion timing based on these inputs.
VEHICLE SPEED AND DISTANCE INPUTÐPCM
INPUT
The transaxle output speed sensor supplies the ve-
hicle speed and distance inputs to the PCM. The out-
put speed sensor is located on the side of the
transaxle (Fig. 12). The speed and distance signals, along with a closed
throttle signal from the TPS, determine if a closed
throttle deceleration or normal idle condition (vehicle
stopped) exists. Under deceleration conditions, the
PCM adjusts the idle air control motor to maintain a
desired MAP value. Under idle conditions, the PCM
adjusts the idle air control motor to maintain a de-
sired engine speed.
AIR CONDITIONING (A/C) CLUTCH RELAYÐPCM
OUTPUT
The PCM operates the air conditioning clutch relay
ground circuit (Fig. 14). The ignition switch supplies
battery voltage to the solenoid side of the relay.
When the A/C clutch relay energizes, battery voltage
powers the A/C compressor clutch. With the engine operating and the blower motor
switch in the On position, the PCM cycles the air
conditioning clutch on and off when the A/C switch
closes. When the PCM senses low idle speeds or wide
open throttle through the throttle position sensor, it
de-energizes the A/C clutch relay. The relay contacts
open, preventing air conditioning clutch engagement.
GENERATOR FIELDÐPCM OUTPUT
The PCM regulates the charging system voltage
Fig. 13 Throttle Position Sensor
Fig. 12 Park Neutral SwitchÐ4-Speed Electronic Automatic Transaxle
14 - 150 FUEL SYSTEMS Ä

operator that the PCM has entered a Limp-in mode.
During Limp-in Mode, the PCM attempts to keep the
system operational. The malfunction indicator signals
the need for immediate service. In limp-in mode, the
PCM compensates for the failure of certain components
that send incorrect signals. The PCM substitutes for
the incorrect signals with inputs from other sensors. Signals that can trigger the Malfunction Indi-
cator lamp (Check Engine Lamp).
² Engine Coolant Temperature Sensor
² Manifold Absolute Pressure Sensor
² Throttle Position Sensor
² Battery Voltage Input
² An Emission Related System (California vehicles)
² Charging system
The malfunction indicator (Check Engine Lamp) can
also display diagnostic trouble codes. Cycle the ignition
switch on, off, on, off, on, within five seconds and any
diagnostic trouble codes stored in the PCM will be
displayed. Refer to the 3.3L and 3.8L Multi-Port Fuel
InjectionÐOn-Board Diagnostics section of this Group
for Diagnostic Trouble Code Descriptions.
DATA LINK CONNECTORÐPCM OUTPUT
The data link connector provides the technician with
the means to connect the DRBII scan tool to diagnosis
the vehicle.
TRANSAXLE CONTROL MODULEÐPCM OUTPUT
The PCM supplies the following information to the
electronic automatic transaxle control module through
the CCD Bus:
² battery temperature
² brake switch input
² engine coolant temperature
² manifold absolute pressure (MAP)
² speed control information
ELECTRIC EGR TRANSDUCER (EET)
SOLENOIDÐPCM OUTPUT
The electronic EGR transducer (EET) contains an
electrically operated solenoid and a back-pressure
transducer (Fig. 16). The PCM operates the solenoid.
The PCM determines when to energize the solenoid.
Exhaust system back-pressure controls the transducer. When the PCM energizes the solenoid, vacuum does
not reach the EGR valve. Vacuum flows to the EGR
valve when the PCM de-energizes the solenoid. When exhaust system back-pressure becomes high
enough, it fully closes a bleed valve in the transducer.
When the PCM de-energizes the solenoid and back-
pressure closes the transducer bleed valve, vacuum
flows through the transducer to operate the EGR valve. De-energizing the solenoid, but not fully closing the
transducer bleed hole (because of by low back- pressure), varies the strength of vacuum applied to
the EGR valve. Varying the strength of the vacuum
changes the amount of EGR supplied to the engine.
This provides the correct amount of exhaust gas re-
circulation for different operating conditions.
FUEL INJECTORSÐPCM OUTPUT
The fuel injectors are electrical solenoids (Fig. 17).
The injector contains a pintle that closes off an ori-
fice at the nozzle end. When electric current is sup-
plied to the injector, the armature and needle move a
short distance against a spring, allowing fuel to flow
out the orifice. Because the fuel is under high pres-
sure, a fine spray is developed in the shape of a hol-
low cone. The spraying action atomizes the fuel,
adding it to the air entering the combustion cham-
ber. The injectors are positioned in the intake mani-
fold.
The fuel injectors are operated by the PCM. They
are energized in a sequential order during all engine
operating conditions except start up. The PCM ini-
tially energizes all injectors at the same time. Once
Fig. 16 Electric EGR Transducer (EET) Assembly
Fig. 17 Fuel InjectorÐ3.3L Engine
14 - 152 FUEL SYSTEMS Ä

the PCM determines crankshaft position, it begins
energizing the injectors in sequence.The auto shutdown (ASD) relay supplies battery
voltage to the injectors. The PCM provides the
ground path for the injectors. By switching the
ground path on and off, the PCM adjusts injector
pulse width. Pulse width is the amount of time the
injector is energized. The PCM adjusts injector pulse
width based on inputs it receives.
IGNITION COILÐPCM OUTPUT
The coil assembly consists of 3 molded coils to-
gether (Fig. 18). The coil assembly is mounted on the
intake manifold. High tension leads route to each
cylinder from the coil. The coil fires two spark plugs
every power stroke. One plug is the cylinder under
compression, the other cylinder fires on the exhaust
stroke. The PCM determines which of the coils to
charge and fire at the correct time.
The auto shutdown (ASD) relay provides battery
voltage to the ignition coil. The PCM provides a
ground contact (circuit) for energizing the coil. When
the PCM breaks the contact, the energy in the coil
primary transfers to the secondary, causing the
spark. The PCM will de-energize the ASD relay if it
does not receive the crankshaft position sensor and
camshaft position sensor inputs. Refer to Auto Shut-
down (ASD) Relay/Fuel Pump RelayÐPCM Output
in this section for relay operation.
RADIATOR FAN RELAYÐPCM OUTPUT
The radiator fan is energized by the PCM through
the radiator fan relay. The radiator fan relay is lo-
cated on the drivers side fender well near the PCM
(Fig. 14). The PCM grounds the radiator fan relay
when engine coolant reaches a predetermined tem-
perature or the A/C system head pressure is high.
SPEED CONTROL SOLENOIDSÐPCM OUTPUT
The speed control vacuum and vent solenoids are
operated by the PCM. When the PCM supplies a ground to the vacuum and vent solenoids, the speed
control system opens the throttle blade. When the PCM
supplies a ground only to the vent solenoid, the throttle
blade holds position. When the PCM removes the
ground from both the vacuum and vent solenoids, the
throttle blade closes. The PCM balances the two sole-
noids to maintain the set speed. Refer to Group 8H for
speed control information.
TACHOMETERÐPCM OUTPUT
The PCM supplies engine RPM to the instrument
panel tachometer through the CCD Bus. The CCD Bus
is a communications port. Various modules use the
CCD Bus to exchange information. Refer to Group 8E
for more information.
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 different 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 pro-
gramming. Input from the oxygen (O
2) sensor is not
monitored during Open Loop modes. During Closed Loop modes the PCM does monitor
the oxygen (O
2) sensor input. This input indicates to
the PCM whether or not the calculated injector pulse
width results in the ideal air-fuel ratio of 14.7 parts air
to 1 part fuel. By monitoring the exhaust oxygen
content through the O
2sensor, the PCM can fine tune
the injector pulse width. Fine tuning injector pulse
width allows the PCM to achieve optimum fuel
economy combined with low emissions. The 3.3L multi-port fuel injection system has the
following modes of operation:
² Ignition switch ON (Zero RPM)
² Engine start-up
² Engine warm-up
² Cruise (Idle)
² Acceleration
² Deceleration
² Wide Open Throttle
² Ignition switch OFF
The engine start-up (crank), engine warm-up, and
wide open throttle modes are OPEN LOOP modes.
Under most operating conditions, the acceleration,
deceleration, and cruise modes, with the engine at
operating temperature are CLOSED LOOP modes.
Fig. 18 Coil PackÐ3.3L Engine
Ä FUEL SYSTEMS 14 - 153

TRANSAXLE
CONTENTS
page page
41TE FOUR SPEED AUTOMATIC TRANSAXLE . 85
41TE FOUR SPEED TRANSAXLE HYDRAULICSCHEMATICS ........................ 170
41TE ON-BOARD DIAGNOSTICS .......... 145
A-523, A-543, and A-568 MANUAL TRANSAXLE ........................... 1 SPECIFICATIONS
...................... 183
THREE SPEED TORQUEFLITE AUTOMATIC TRANSAXLE .......................... 35
THREE SPEED TRANSAXLE HYDRAULIC SCHEMATICS ........................ 162
A-523, A-543, and A-568 MANUAL TRANSAXLE INDEX
page page
Bearing Adjustment Procedure .............. 31
Differential Bearing Preload Adjustment ........ 33
Gearshift Linkage Adjustment (Cable Operated) . . 2
General Information ........................ 1 In-Car Transaxle Disassemble/Assemble
........ 4
Out of Car TransaxleÐDisassemble and Assemble . 6
Subassembly-Recondition .................. 15
Transaxle Removal and Installation ............ 5
GENERAL INFORMATION
Safety goggles should be worn at all times
when working on these transaxles. All manual
transaxles use SAE 5W-30 engine oil, meeting SG
and/or SG-CC qualifications, as the lubricant in order
to reduce wear. This 5-speed manual transaxles combine gear reduc-
tion, ratio selection, and differential functions in one
unit. It is housed in a die-cast aluminum case (Fig. 1). All shift forks are cast iron.
Do not interchange 1-2
or 5th shift fork pads with the 3-4 shift fork pads.
All synchronizers use a winged strutdesign that
prevents the struts from popping out of position. If any synchronizer is to be disassembled, mark
all parts so that they will be reassembled in the
same position.
CAUTION: 1-2 synchronizer assembly components
must NOT be interchanged with any other synchro-
nizer assembly. Do not interchange with previous
model years transaxles; they will NOT function cor-
rectly.
A-523 AND A-543 MANUAL TRANSAXLE
The A-523 manual transaxle is used in all 4-cylinder
applications, except high output turbocharged engines.
The A-543 manual transaxle is used only with V-6
engines. To reduce wear, the manual transaxle uses SAE
5W-30 engine oil as the lubricant. Gear ratios for the A-523 and A-543 are as follows:
1stÐ3.31, 2cdÐ2.06, 3rdÐ1.36, 4thÐ0.97, 5thÐ0.71,
ReverseÐ3.14. The final drive ratio is 3.77.
CAUTION: All gears and shafts must not be inter-
changed with previous model years; they will not
function correctly.
Fig. 1 External Transaxle Components
Ä TRANSAXLE 21 - 1