steering DODGE NEON 2000 Service Repair Manual

(17) Install rear timing belt cover and camshaft
sprocket.
(18) Install crankshaft sprocket, timing belt ten-
sioner, timing belt, and cover.
(19) Install front engine mount bracket.
(20) Remove engine from repair stand and position
on Special Tools 6135 and 6710 Engine Dolly and
Cradle. Install safety straps around the engine to
cradle and tighten and lock them into position.
(21) Install crankshaft rear oil seal. Refer to proce-
dure in this section.
(22) Install drive plate/flywheel. Apply Mopart
Lock & Seal Adhesive to bolt threads and tighten to
95 N´m (70 ft. lbs.).
(23) Install transaxle to engine.
(24) Install structural collar. Refer to procedure in
this section.
(25) Install engine assembly. Refer to procedure in
this section.
(26) Perform camshaft and crankshaft timing
relearn procedure as follows:
²Connect 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.
²Turn the ignition switch on and access the ªmis-
cellaneousº screen.
²Select ªre-learn cam/crankº option and follow
directions on DRB screen.
OIL FILTER ADAPTER
REMOVE AND INSTALL
Ensure O-ring is in the groove on adapter. Align
roll pin into engine block and tighten assembly to 80
N´m (60 ft. lbs.) (Fig. 101).
OIL FILTER
REMOVE AND INSTALL
CAUTION: When servicing the oil filter (Fig. 102),
avoid deforming the filter. Use an appropriate oil fil-
ter removing tool. Position filter wrench strap close
the seam at the base of the filter. The oil filter seam
that joins the can to the base, is reinforced by the
base plate.
(1) Turn filter counterclockwise to remove.
(2) Clean and check the filter mounting surface.
The surface must be smooth, flat and free of debris
or old pieces of rubber.
(3) To install, lubricate new filter gasket. Screw fil-
ter on until gasket contacts base. Tighten to 21 N´m
(15 ft. lbs.).
OIL PUMP
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove crankshaft damper, timing belt, and
tensioner. Refer to procedures in this section.
(3) Remove camshaft sprocket and rear timing belt
cover. Refer to procedures in this section.
(4) Remove oil pan. Refer to procedure in this sec-
tion.
(5) Remove crankshaft sprocket using Special Tool
6793 and insert C-4685-C2 (Fig. 103).
(6) Remove oil pick-up tube.
(7) Remove oil pump (Fig. 104) and front crank-
shaft seal.
Fig. 101 Engine Oil Filter Adapter to Engine Block
1 ± O-RING
2 ± LOCATING ROLL PIN
3 ± OIL FILTER ADAPTER
Fig. 102 Engine Oil Filter
1 ± OIL FILTER
2 ± DRAIN PLUG
PL2.0L SOHC ENGINE 9 - 55
REMOVAL AND INSTALLATION (Continued)

FRAMES
TABLE OF CONTENTS
page page
DESCRIPTION AND OPERATION
FRONT SUSPENSION......................5
REMOVAL AND INSTALLATION
FRONT SUSPENSION CROSSMEMBER........5SPECIFICATIONS
FRAME DIMENSIONS......................9
STRUCTURAL DIMENSIONS................13
TORQUE SPECIFICATIONS.................15
DESCRIPTION AND OPERATION
FRONT SUSPENSION
The front suspension crossmember must be prop-
erly installed to achieve design camber, caster set-
tings and wheel stagger. The crossmember can be
installed out of position on the frame rails due to its
design. Bolts and cage nuts hold the rear of the
crossmember to the frame torque boxes. Bolts and
J-nuts hold the front of the crossmember to the
frame rails. No designed in locating device is used to
position the crossmember in the vehicle. Before
removing the crossmember mark the frame torque
box around the rear mounting location to aid instal-
lation. A crossmember that is removed during service
must be installed in the same position from which it
was removed. To verify that crossmember is in the
proper position, refer to the dimensions provided.
Front end dimensions are gauged from the principal
locating point (PLP) holes located under the frame
torque boxes rearward of the front wheels. After
removal and installation of the crossmember is per-
formed, verify that front suspension alignment is
within specifications. If camber, caster settings and
wheel stagger is not within specifications, loosen and
reposition crossmember to bring suspension within
specifications. Refer to Group 2, Front Suspension for
additional information.
REMOVAL AND INSTALLATION
FRONT SUSPENSION CROSSMEMBER
CAUTION: If the front suspension crossmember is
being replaced due to collision damage, inspect the
steering column lower coupling for damage. Refer
to STEERING COLUMN in the STEERING service
manual group for the procedure.
REMOVAL
(1) Raise the vehicle. Refer to HOISTING in the
LUBRICATION AND MAINTENANCE group in this
service manual for the correct lifting procedure.
(2) Remove both front tire and wheel assemblies
from the vehicle.
(3) Remove both stabilizer bar links from the vehi-
cle (Fig. 1). Remove each link by holding the upper
retainer/nut with a wrench and turning the link bolt.
(4) Remove the stabilizer bar cushion retainer
bolts and retainers (Fig. 1), and remove the stabilizer
bar with cushions attached from the vehicle.
(5) Remove the nut and pinch bolt clamping each
ball joint stud to the steering knuckle (Fig. 2).
Fig. 1 Stabilizer Bar
1 ± STABILIZER BAR CUSHION RETAINERS
2 ± CUSHIONS
3 ± FRONT STABILIZER BAR
4 ± STABILIZER BAR LINKS
PLFRAME AND BUMPERS 13 - 5

CAUTION: After removing the steering knuckle from
the ball joint stud, do not pull outward on the knuckle.
Pulling the steering knuckle outward at this point can
separate the inner C/V joint on the driveshaft. Refer to
FRONT DRIVESHAFTS in the DIFFERENTIAL AND
DRIVELINE group for further information.
NOTE: Use caution when separating the ball joint
stud from the steering knuckle, so the ball joint seal
does not get cut.
(6) Separate each ball joint stud from the steering
knuckle by prying down on lower control arm and up
against the ball joint boss on the steering knuckle
(Fig. 3).
(7) If the vehicle is equipped with a power steering
fluid cooler, remove the two screws securing the
cooler to the front suspension crossmember. They are
located behind the cooler and can be accessed from
above. Allow the cooler to hang out of the way.
(8) Using wire or cord, support and tie off the
power steering gear to the underbody of the vehicle,
so when the crossmember is lowered, the gear does
not fall away being held to the vehicle by only the
steering column coupler and the fluid hoses.
(9) Loosen and remove the four bolts attaching the
power steering gear to the front suspension cross-
member (Fig. 4). Remove the power steering gear
from the front suspension crossmember.
(10) Remove the bolt mounting the engine torque
strut to the right forward corner of the front suspen-
sion crossmember (Fig. 5).
NOTE: Before removing the front suspension
crossmember from the vehicle, the location of thecrossmember must be scribed on the body of the
vehicle (Fig. 9). Do this so that the crossmember
can be relocated upon reinstallation against the
body of vehicle in the same location as before
removal. If the front suspension crossmember is
not reinstalled in exactly the same location as
before removal, the preset front wheel alignment
settings (caster and camber) will be lost.
(11) Using an awl, scribe a line (Fig. 6) marking
the location of where the front suspension crossmem-
ber is mounted against the body of the vehicle.
(12) Position a transmission jack under the center
of the front suspension crossmember and raise it to
support the bottom of the crossmember.
(13) Loosen and completely remove the two front
bolts (one right and one left) attaching the front sus-
pension crossmember to the frame rails of vehicle.
The right side bolt can be viewed in the mounting
bolt figure (Fig. 5). The left side bolt is located in the
same location on the other side of the vehicle.
(14) Loosen the two rear bolts (one right and one
left) attaching the front suspension crossmember and
lower control arms to the body of the vehicle until
they release from the threaded tapping plates in the
body of the vehicle. Remove the rear bolts from the
body of the vehicle, but do not completely remove the
rear bolts because they are designed to disengage
from the body threads yet stay within the lower con-
trol arm rear isolator bushing. This allows the lower
control arm to stay in place on the crossmember. The
right side bolt can be viewed in the mounting bolt
figure (Fig. 5). The left side bolt is located in the
same location on the other side of the vehicle.
(15) Lower the front suspension crossmember.
Fig. 2 Ball Joint Bolt And Nut
1 ± NUT
2 ± BOLT
3 ± BALL JOINT
Fig. 3 Pry Bar Usage
1 ± STEERING KNUCKLE
2±PRYBAR
3 ± LOWER CONTROL ARM
4 ± BALL JOINT STUD
13 - 6 FRAME AND BUMPERSPL
REMOVAL AND INSTALLATION (Continued)

(16) Remove each lower control arm from the
crossmember by removing the front pivot bolt.
INSTALLATION
(1) Install the lower control arms on the front sus-
pension crossmember. Install the pivot bolts, but do
not completely tighten them at this time.(2) Using the transmission jack, raise the front
suspension crossmember and lower control arms
until the crossmember contacts its mounting spot
against the body and frame rails of the vehicle. As
the crossmember is raised, carefully guide the power
steering gear into mounting position.
Fig. 4 Steering Gear Mounting
1 ± OUTER TIE ROD
2 ± JAM NUT3 ± STEERING GEAR
4 ± FRONT SUSPENSION CROSSMEMBER
Fig. 5 Mounting Bolts
1 ± FRONT SUSPENSION CROSSMEMBER MOUNTING BOLTS
2 ± ENGINE TORQUE ISOLATOR STRUT MOUNTING BOLT
3 ± FRONT SUSPENSION CROSSMEMBER
Fig. 6 Marking Crossmember Location
1 ± SCRIBED LINE
2 ± FRONT SUSPENSION CROSSMEMBER
3±AWL
4 ± BODY
PLFRAME AND BUMPERS 13 - 7
REMOVAL AND INSTALLATION (Continued)

(3) Start the two rear crossmember mounting bolts
into the tapping plates mounted in the body. The
right side bolt can be viewed in the mounting bolt
figure (Fig. 5). The left side bolt is located in the
same location on the other side of the vehicle. Next,
install the two front mounting bolts attaching front
suspension crossmember to frame rails of vehicle.
Lightly tighten all four mounting bolts to a approxi-
mately 2 N´m (20 in. lbs.) to hold the front suspen-
sion crossmember in position.
NOTE: When reinstalling the front suspension
crossmember back in the vehicle, it is very impor-
tant that the crossmember be attached to the body
in exactly the same spot as when it was removed.
Otherwise, the vehicle's wheel alignment settings
(caster and camber) will be lost.
(4) Using a soft face hammer, tap the front suspen-
sion crossmember back-and-forth or side-to-side until
it is aligned with the previously scribed positioning
marks on the body of the vehicle (Fig. 6). Once the
front suspension crossmember is correctly positioned,
tighten the rear two crossmember mounting bolts to
a torque of 203 N´m (150 ft. lbs.), then tighten the
front two crossmember mounting bolts to a torque of
142 N´m (105 ft. lbs.).
(5) Tighten the lower control arm front pivot bolts
to a torque of 163 N´m (120 ft. lbs.).
(6) Attach the steering gear to the front suspen-
sion crossmember (Fig. 4). Install the four power
steering gear mounting bolts. Tighten the mounting
bolts to a torque of 61 N´m (45 ft. lbs.).
(7) Remove the wire or cord suspending the power
steering gear to the underbody.
(8) If the vehicle is equipped with a power steering
fluid cooler, install the two screws securing the cooler
to the front suspension crossmember. They are
located behind the cooler.
(9)
Install each ball joint stud into the steering
knuckle aligning the bolt hole in the knuckle boss with
the notch formed in the side of the ball joint stud.
(10) Install a new ball joint stud pinch bolt and
nut (Fig. 2). Tighten the nut to a torque of 95 N´m
(70 ft. lbs.).
(11) Fasten the engine torque strut to the right
forward corner of the front suspension crossmember
using its mounting bolt (Fig. 5). Follow the procedure
described in the ENGINE service manual group to
properly align and tighten the torque strut and it's
mounting bolts.
NOTE: Before installing the stabilizer bar, make
sure the bar is not upside-down. The stabilizer bar
must be installed with the curve on the outboard
ends of the bar facing downward to clear the con-
trol arms once fully installed (Fig. 7).(12)
First, place the stabilizer bar in position on the
front suspension crossmember. The slits in each cush-
ion must point toward the front of the vehicle and sit
directly on top of the raised beads formed into the
stamping on the crossmember. Next, install the cush-
ion retainers, matching the raised beads formed into
the cushion retainers to the grooves formed into the
cushions. Install the cushion retainer bolts, but do not
completely tighten them at this time.
(13) Install both stabilizer bar links back on vehi-
cle (Fig. 1). Start each stabilizer bar link bolt with
bushing from the bottom, through the stabilizer bar,
inner link bushings, lower control arm, and into the
upper retainer/nut and bushing. Do not fully tighten
the link assemblies at this time.
(14) Install the tire and wheel assemblies back on
vehicle. Tighten the wheel mounting nuts to 135 N´m
(100 ft. lbs.) torque.
(15) Lower the vehicle.
NOTE: It may be necessary to put the vehicle on a
platform hoist or alignment rack to gain access to
the stabilizer bar mounting bolts with the vehicle at
curb height.
(16) Tighten each stabilizer bar link by holding the
upper retainer/nut with a wrench and turning the
link bolt. Tighten each link bolt to a torque of 23
N´m (200 in. lbs.).
(17) Tighten the stabilizer bar cushion retainer
bolts to a torque of 34 N´m (300 in. lbs.).
(18) Check the front wheel alignment on the vehi-
cle. Refer to WHEEL ALIGNMENT in the SUSPEN-
SION service manual group.
Fig. 7 Downward Curve
1 ± STABILIZER BAR
2 ± LINK
3 ± DOWNWARD CURVE
4 ± CUSHION RETAINER
13 - 8 FRAME AND BUMPERSPL
REMOVAL AND INSTALLATION (Continued)

FUEL INJECTION SYSTEM
TABLE OF CONTENTS
page page
DESCRIPTION AND OPERATION
INJECTION SYSTEM......................22
MODES OF OPERATION...................22
SYSTEM DIAGNOSIS......................24
POWER DISTRIBUTION CENTER............24
POWERTRAIN CONTROL MODULE...........24
PCM GROUND...........................26
5 VOLT SUPPLYÐPCM OUTPUT.............26
8-VOLT SUPPLYÐPCM OUTPUT.............26
FUEL CORRECTION or ADAPTIVE MEMORIES . . 26
PROGRAMMABLE COMMUNICATIONS
INTERFACE (PCI) BUS...................27
AIR CONDITIONING PRESSURE
TRANSDUCERÐPCM INPUT..............27
AUTOMATIC SHUTDOWN (ASD) SENSEÐ
PCM INPUT...........................27
BATTERY VOLTAGEÐPCM INPUT............28
BRAKE SWITCHÐPCM INPUT...............28
CAMSHAFT POSITION SENSORÐPCM INPUT . . 28
CLUTCH INTERLOCK/UPSTOP SWITCH.......29
CRANKSHAFT POSITION SENSORÐPCM
INPUT................................30
ENGINE COOLANT TEMPERATURE
SENSORÐPCM INPUT...................30
FUEL LEVEL SENSORÐPCM INPUT..........31
HEATED OXYGEN SENSOR (O2 SENSOR)Ð
PCM INPUT...........................32
IGNITION CIRCUIT SENSEÐPCM INPUT......34
INLET AIR TEMPERATURE SENSORÐPCM
INPUT................................34
KNOCK SENSORÐPCM INPUT..............34
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSORÐPCM INPUT...................35
POWER STEERING PRESSURE SWITCHÐ
PCM INPUT...........................35
SENSOR RETURNÐPCM INPUT.............35
SPEED CONTROLÐPCM INPUT.............36
SCI RECEIVEÐPCM INPUT.................36
PARK/NEUTRAL POSITION SWITCHÐPCM
INPUT................................36
THROTTLE POSITION SENSORÐPCM INPUT . . 36VEHICLE SPEED SIGNAL (VSS)ÐPCM INPUT . . 37
AIR CONDITIONING CLUTCH RELAYÐPCM
OUTPUT..............................38
AUTOMATIC SHUTDOWN RELAYÐPCM
OUTPUT..............................38
CHARGING SYSTEM INDICATOR LAMPÐPCM
OUTPUT..............................38
FUEL PUMP RELAYÐPCM OUTPUT..........38
PROPORTIONAL PURGE SOLENOIDÐPCM
OUTPUT..............................39
GENERATOR FIELDÐPCM OUTPUT..........39
IDLE AIR CONTROL MOTORÐPCM OUTPUT . . . 39
DATA LINK CONNECTOR...................40
FUEL INJECTORSÐPCM OUTPUT...........40
IGNITION COILÐPCM OUTPUT..............40
MALFUNCTION INDICATOR (CHECK ENGINE)
LAMPÐPCM OUTPUT...................41
SPEED CONTROLÐPCM INPUT.............41
SCI RECEIVEÐPCM OUTPUT...............41
TACHOMETERÐPCM OUTPUT..............42
TORQUE CONVERTOR CLUTCH SOLENOIDÐ
PCM OUTPUT..........................42
REMOVAL AND INSTALLATION
THROTTLE BODY........................42
THROTTLE POSITION SENSOR.............43
IDLE AIR CONTROL MOTOR................43
MAP SENSOR...........................44
POWERTRAIN CONTROL MODULE (PCM).....44
UPSTREAM HEATED OXYGEN SENSOR......45
DOWNSTREAM HEATED OXYGEN SENSOR
1/2 ..................................46
AIR CLEANER BOX.......................46
AIR CLEANER ELEMENT...................47
ENGINE COOLANT TEMPERATURE SENSOR . . . 47
VEHICLE SPEED SENSOR.................47
KNOCK SENSOR.........................48
SPECIFICATIONS
VECI LABEL.............................49
TORQUE...............................49
SPECIAL TOOLS
FUEL..................................49
PLFUEL SYSTEM 14 - 21

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. If
the PCM does not detect a minimum difference
between the two values, it sets a MAP diagnostic
trouble code into memory.
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
²Intake 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:
²Engine coolant temperature
²Manifold Absolute Pressure (MAP)
²Intake air temperature (IAT)²Crankshaft position (engine speed)
²Camshaft position
²Knock sensor
²Throttle position
²A/C switch
²Battery voltage
²Power steering pressure switch
²Vehicle speed
²Speed control
²O2 sensors
²All diagnostics
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:
²Intake 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
²Power steering pressure switch
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)
²Fuel system monitor
²EGR monitor
²Purge system monitor
PLFUEL SYSTEM 14 - 23
DESCRIPTION AND OPERATION (Continued)

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
²Power steering pressure switch
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 pressure transducer
²A/C sense
²Battery voltage
²Intake air temperature
²Engine coolant temperature
²Crankshaft position (engine speed)
²Exhaust gas oxygen content (upstream heated
oxygen sensor)
²Knock sensor
²Manifold absolute pressure
²Power steering pressure switch
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.
If decel fuel shutoff is detected, downstream oxy-
gen sensor diagnostics is performed.WIDE-OPEN-THROTTLE MODE
This is an OPEN LOOP mode. During wide-open-
throttle operation, the following inputs are received
by the PCM:
²Intake 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.
SYSTEM DIAGNOSIS
OPERATION
The PCM can test many of its own input and out-
put circuits. If the PCM senses a fault in a major
system, the PCM stores a Diagnostic Trouble Code
(DTC) in memory.
For DTC information see On-Board Diagnostics.
POWER DISTRIBUTION CENTER
The Power Distribution Center (PDC) is located
next to the battery (Fig. 1). The PDC contains the
starter relay, radiator fan relay, A/C compressor
clutch relay, auto shutdown relay, fuel pump relay
and several fuses.
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
engine and vehicle operations through devices that
are referred to as PCM Outputs.
PCM Inputs:
14 - 24 FUEL SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

²Air Conditioning Controls
²Battery Voltage
²Inlet Air/Battery Temperature Sensor
²Brake Switch
²Camshaft Position Sensor
²Crankshaft Position Sensor
²Engine Coolant Temperature Sensor
²Fuel Level Sensor
²Ignition Switch
²Inlet Air/Intake Air Temperature Sensor
²Knock Sensor
²Manifold Absolute Pressure (MAP) Sensor
²Oxygen Sensors
²Power Steering Pressure Switch²SCI Receive
²Speed Control Switches
²Throttle Position Sensor
²Transmission Park/Neutral Switch (automatic
transmission)
²Vehicle Speed Sensor
PCM Outputs:
²Air Conditioning WOT Relay
²Auto Shutdown (ASD) Relay
²Charging Indicator Lamp
²Data Link Connector
²Proportional Purge Solenoid
²EGR Solenoid
²Fuel Injectors
²Fuel Pump Relay
²Generator Field
²Idle Air Control Motor
²Ignition Coils
²Malfunction Indicator (Check Engine) Lamp
²Radiator Fan Relay
²Speed Control Solenoids
²Tachometer
²Torque Convertor Clutch Solenoid
Based on inputs it receives, the PCM adjusts fuel
injector pulse width, idle speed, ignition spark
advance, ignition coil dwell and EVAP 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 also performs diagnostics.
The PCM adjusts injector pulse width (air-fuel
ratio) based on the following inputs.
²Battery voltage
²Coolant temperature
²Inlet Air/Intake air temperature
²Exhaust gas content (oxygen sensor)
²Engine speed (crankshaft position sensor)
²Manifold absolute pressure
²Throttle position
The PCM adjusts ignition timing based on the fol-
lowing inputs.
²Coolant temperature
²Inlet Air/Intake air temperature
²Engine speed (crankshaft position sensor)
²Knock sensor
²Manifold absolute pressure
²Throttle position
²Transmission gear selection (park/neutral
switch)
The PCM also adjusts engine idle speed through
the idle air control motor based on the following
inputs.
²Air conditioning sense
²Battery voltage
²Battery temperature
²Brake switch
Fig. 1 Power Distribution Center (PDC)
Fig. 2 Powertrain Control Module (PCM)
1 ± PCM
PLFUEL SYSTEM 14 - 25
DESCRIPTION AND OPERATION (Continued)

²Coolant temperature
²Engine speed (crankshaft position sensor)
²Engine run time
²Manifold absolute pressure
²Power steering pressure switch
²Throttle position
²Transmission gear selection (park/neutral
switch)
²Vehicle distance (speed)
The Auto Shutdown (ASD) and fuel pump relays
are mounted externally, but turned on and off by the
PCM.
The crankshaft position sensor signal is sent to the
PCM. If the PCM does not receive the signal within
approximately one second of engine cranking, it deac-
tivates the ASD relay and fuel pump relay. When
these relays deactivate, power is shut off from the
fuel injectors, ignition coils, heating element in the
oxygen sensors and the fuel pump.
The PCM contains a voltage converter that
changes battery voltage to a regulated 8 volts direct
current to power the camshaft position sensor, crank-
shaft position sensor and vehicle speed sensor. The
PCM also provides a 5 volt direct current supply for
the manifold absolute pressure sensor and throttle
position sensor.
PCM GROUND
OPERATION
Ground is provided through multiple pins of the
PCM connector. Depending on the vehicle there may
be as many as three different ground pins. There are
power grounds and sensor grounds.
The power grounds are used to control the ground
side of any relay, solenoid, ignition coil or injector.
The signal ground is used for any input that uses
sensor return for ground, and the ground side of any
internal processing component.
The SBEC III case is shielded to prevent RFI and
EMI. The PCM case is grounded and must be firmly
attached to a good, clean body ground.
Internally all grounds are connected together, how-
ever there is noise suppression on the sensor ground.
For EMI and RFI protection the case is also
grounded separately from the ground pins.
5 VOLT SUPPLYÐPCM OUTPUT
OPERATION
The PCM supplies 5 volts to the following sensors:
²A/C pressure transducer
²Engine coolant temperature sensor
²Manifold absolute pressure sensor
²Throttle position sensor
²Linear EGR solenoid
8-VOLT SUPPLYÐPCM OUTPUT
OPERATION
The PCM supplies 8 volts to the crankshaft posi-
tion sensor, camshaft position sensor.
FUEL CORRECTION or ADAPTIVE MEMORIES
DESCRIPTION
In Open Loop, the PCM changes pulse width with-
out feedback from the O2 Sensors. Once the engine
warms up to approximately 30 to 35É F, the PCM
goes into closed loopShort Term Correctionand
utilitzes feedback from the O2 Sensors. Closed loop
Long Term Adaptive Memoryis maintained above
170É to 190É F unless the PCM senses wide open
throttle. At that time the PCM returns to Open Loop
operation.
OPERATION
Short Term
The first fuel correction program that begins func-
tioning is the short term fuel correction. This system
corrects fuel delivery in direct proportion to the read-
ings from the Upstream O2 Sensor.
The PCM monitors the air/fuel ratio by using the
input voltage from the O2 Sensor. When the voltage
reaches its preset high or low limit, the PCM begins
to add or remove fuel until the sensor reaches its
switch point. The short term corrections then begin.
The PCM makes a series of quick changes in the
injector pulse-width until the O2 Sensor reaches its
opposite preset limit or switch point. The process
then repeats itself in the opposite direction.
Short term fuel correction will keep increasing or
decreasing injector pulse-width based upon the
upstream O2 Sensor input. The maximum range of
authority for short term memory is 25% (+/-) of base
pulse-width.
Long Term
The second fuel correction program is the long
term adaptive memory. In order to maintain correct
emission throughout all operating ranges of the
engine, a cell structure based on engine rpm and load
(MAP) is used.
There are up to 16 cells. Two cells are used only
during idle, based upon TPS and Park/Neutral
switch inputs. There may be two other cells used for
deceleration, based on TPS, engine rpm, and vehicle
speed. The other twelve cells represent a manifold
pressure and an rpm range. Six of the cells are high
rpm and the other six are low rpm. Each of these
cells is a specific MAP voltage range.
14 - 26 FUEL SYSTEMPL
DESCRIPTION AND OPERATION (Continued)