timing DODGE NEON 2000 Service Owner's Guide

CRANKSHAFT
REMOVAL
(1) Remove engine assembly. Refer to procedure in
this section.
(2) Remove structural collar from oil pan to tran-
saxle housing.
(3) Separate transaxle from engine.
(4) Remove drive plate/flywheel.
(5) Remove crankshaft rear oil seal. Refer to pro-
cedure in this section.
(6) Mount engine on a suitable repair stand.
(7) Remove crankshaft damper, timing belt, and
tensioner. Refer to procedures in this section.
(8) Remove camshaft sprocket and rear timing belt
cover. Refer to procedures in this section.
(9) Remove crankshaft sprocket. Refer to proce-
dure in this section.(10) Remove lower torque strut/air conditioning
compressor mounting bracket from engine (Fig. 95).
(11) Remove oil filter and adapter.
(12) Remove oil pan.
(13) Remove oil pump pick-up tube.
(14) Remove oil pump.
(15) Remove crankshaft position sensor.
(16) Using a permanent ink or paint marker, iden-
tify cylinder number on each connecting rod cap.
CAUTION: DO NOT use a number stamp or a punch
to mark connecting rods. Damage to connecting
rod could occur.
(17) Remove all connecting rod bolts and caps.
Care should be taken not to damage the fracture rod
and cap surfaces.
Fig. 94 Crankshaft and Components
1 ± OIL PASSAGE O-RING
2 ± SEAL
3 ± UPPER BEARING (GROOVED)
4 ± THRUST BEARINGS
5 ± BOLT
6 ± O-RING
7 ± NIPPLE8 ± OIL FILTER ADAPTER
9 ± CRANKSHAFT POSITION SENSOR (CPS)
10 ± MAIN BEARING CAP/BED PLATE ASSEMBLY
11 ± CONNECTING ROD BEARINGS
12 ± PISTON AND CONNECTING ROD ASSEMBLY
13 ± SEAL
9 - 52 2.0L SOHC ENGINEPL
REMOVAL AND INSTALLATION (Continued)

(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)

(8) Install oil pick-up tube and oil pan.
(9) Install rear timing belt cover and camshaft
sprocket.
(10) Install timing belt tensioner, timing belt, and
front timing belt cover.
(11) Install crankshaft damper.
(12) Fill engine crankcase with proper oil to cor-
rect level.
(13) Connect negative cable to battery.
PISTON AND CONNECTING ROD
REMOVAL
(1) Remove cylinder head and oil pan. Refer to pro-
cedures in this section.
(2) Remove top ridge of cylinder bores with a reli-
able ridge reamer before removing pistons from cyl-
inder block.Be sure to keep tops of pistons
covered during this operation. Mark piston with
matching cylinder number (Fig. 108).
CAUTION: DO NOT use a number stamp or a punch
to mark connecting rods. Damage to connecting
rod could occur.
(3) Using a permanent ink marker or scribe tool
mark the cylinder number on the side of the rod and
cap (Fig. 109) for identification.
Fig. 105 Oil Pump Sealing
1 ± APPLY GASKET MAKER TO OIL PUMP BODY FLANGE
2 ± O-RING
Fig. 106 Front Crankshaft SealÐInstallation
1 ± PROTECTOR
2 ± SEAL
3 ± SPECIAL TOOL 6780±1
4 ± INSTALLER
Fig. 107 Crankshaft SprocketÐInstallation
1 ± SPECIAL TOOL 6792
2 ± TIGHTEN NUT TO INSTALL
Fig. 108 Piston Markings
1 ± WEIGHT DESIGNATION AND DIRECTIONAL ARROW WILL
BE IMPRINTED IN THIS AREA
PL2.0L SOHC ENGINE 9 - 57
REMOVAL AND INSTALLATION (Continued)

(4) Pistons will have a stamping in the approxi-
mate location shown in (Fig. 108). These stamps will
be either a directional arrow or a weight identifica-
tion for the assembly. L is for light and H is for
heavy. These assemblies should all be the same
weight class. Service piston assemblies are marked
with a S and can be used with either L or H produc-
tion assemblies. The weight designation stamps
should face toward the timing belt side of the engine.
(5) Pistons and connecting rods must be removed
from top of cylinder block. Rotate crankshaft so that
each connecting rod is centered in cylinder bore.
(6) Remove connecting rod cap bolts.Do not use
old bolts if reinstalling connecting rod.
(7) To protect crankshaft journal and fractured rod
surfaces, install Special Tool 8189, connecting rod
guides onto connecting rod (Fig. 110). Carefully push
each piston and rod assembly out of cylinder bore.
CAUTION: Care must be taken not to damage the
fractured rod and cap joint surfaces, as engine
damage many occur.
(8) Remove Special Tool 8189, connecting rod
guides and re-install bearing cap on the mating rod.
NOTE: Piston and rods are serviced as an assem-
bly.
PISTON RINGÐREMOVAL
(1) The identification mark on face of upper and
intermediate piston rings must point toward piston
crown.
(2) Using a suitable ring expander, remove upper
and intermediate piston rings (Fig. 111).
(3) Remove the upper oil ring side rail, lower oil
ring side rail and then oil ring expander from piston.
(4) Clean ring grooves of any carbon deposits.
PISTON RINGSÐINSTALLATION
(1) Install rings with manufacturers identification
mark facing up, to the top of the piston (Fig. 112).CAUTION: Install piston rings in the following
order:
a. Oil ring expander.
b. Upper oil ring side rail.
c. Lower oil ring side rail.
d. No. 2 Intermediate piston ring.
e. No. 1 Upper piston ring.
f. Install the side rail by placing one end between
the piston ring groove and the expander. Hold end
firmly and press down the portion to be installed
until side rail is in position.Do not use a piston
ring expander (Fig. 113).
(2) Install upper side rail first and then the lower
side rail.
(3) Install No. 2 piston ring and then No. 1 piston
ring (Fig. 112).
(4) Position piston ring end gaps as shown in (Fig.
114).
Fig. 109 Identify Connecting Rod to Cylinder
Fig. 110 Connecting Rod GuidesÐTypical
1 ± SPECIAL TOOL 8189 CONNECTING ROD GUIDES
Fig. 111 Piston RingsÐRemoving and Installing
9 - 58 2.0L SOHC ENGINEPL
REMOVAL AND INSTALLATION (Continued)

DESCRIPTION SPECIFICATION
No. 3 41.928±41.947 mm
(1.650±1.651 in.)
No. 4 42.328±42.374 mm
(1.666±1.668 in.)
No. 5 42.728±42.747 mm
(1.682±1.6829 in.)
Bearing ClearanceÐ
Diametrical0.053±0.093 mm
(0.0027±0.003 in.)
Bearing Clearance (Max.
allowable)0.12 mm
(0.0047 in.)
End Play 0.05±0.39 mm
(0.002±0.015 in.)
Lift (Zero Lash)
Intake 7.2 mm
(0.283 in.)
Exhaust 7.03 mm
(0.277 in.)
Exhaust Valve Timing*
Closes (ATDC) 5.4É
Opens (BBDC) 43.7É
Duration 229.1É
Intake Valve Timing*
Closes (ABDC) 41.1É
Opens (ATDC) 13.9É
Duration 207.2É
Valve Overlap 84.8É
*All readings in crankshaft degrees, at 0.5 mm (0.019
in.) of valve lift.
Cylinder Head
Material Cast Aluminum
Gasket Thickness
(Compressed)1.15 mm
(0.045 in.)
Valve Seat
Angle 45É
Seat DiameterÐIntake 33 mm
(1.299 in.)
Seat DiameterÐExhaust 28 mm
(1.102 in.)
Runout (Max.) 0.05 mm
(0.002 in.)
Valve Seat WidthÐIntake
and Exhaust0.9±1.3 mm
(0.035±0.051 in.)DESCRIPTION SPECIFICATION
Service LimitÐIntake 2.0 mm
(0.079 in.)
Service LimitÐExhaust 2.5 mm
(0.098 in.)
Valve Guide
Diameter I. D. 5.975±6.000 mm
(0.235±0.236 in.)
Guide Bore Diameter
(Std.)11.0±11.02 mm
(0.4330±0.4338 in.)
Guide Height (spring seat
to guide tip)13.25±13.75 mm
(0.521±0.541 in.)
Valves
Face Angle Intake and
Exhaust45±45.5É
Head DiameterÐIntake 32.12±33.37 mm
(1.303±1.313 in.)
Head DiameterÐExhaust 28.57±28.83 mm
(1.124±1.135 in.)
Valve Margin
Intake 1.15±1.48 mm
(0.0452±0.0583 in.)
Service Limit 0.95 mm
(1/32 in.)
Exhaust 1.475±1.805 mm
(0.058±0.071 in.)
Service Limit 1.05 mm
(3/64 in.)
Valve Length (Overall)
Intake 114.69±115.19 mm
(4.515±4.535 in.)
Exhaust 116.94±117.44 mm
(4.603±4.623 in.)
Valve Stem Tip Height
Intake 45.01±46.07 mm
(1.77±1.81 in.)
Exhaust 43.51±44.57 mm
(1.71±1.75 in.)
Valve Stem Diameter
Intake 5.934±5.952 mm
(0.2337±0.2344 in.)
9 - 70 2.0L SOHC ENGINEPL
SPECIFICATIONS (Continued)

DESCRIPTION SPECIFICATION
Exhaust 5.906±5.924 mm
(0.2326±0.2333 in.)
Valve Stem to Guide Clearance
Intake 0.048±0.066 mm
(0.0018±0.0025 in.)
Max. Allowable 0.076 mm
(0.003 in.)
Service Limit 0.25 mm
(0.010 in.)
Exhaust 0.0736±0.094 mm
(0.0029±0.0037 in.)
Max. Allowable 0.101 mm
(0.004 in.)
Service Limit 0.25 mm
(0.010 in.)
Valve Springs
Free Length (Approx.) 46.75 mm
(1.84 in.)
Nominal Force (Valve
Closed)331 N @ 39.8 mm
(70 lbs. @ 1.57 in.)
Nominal Force (Valve
Open)711 N @ 32.6 mm
(160 lbs. @ 1.28 in.)
Installed Height 40.18 mm
(1.580 in.)
TORQUE
DESCRIPTION N´mFt.
Lbs.In.
Lbs.
Camshaft Sensor
Pick-upÐBolts9.6 Ð 85
Camshaft SprocketÐBolt 115 85 Ð
Connecting Rod
CapÐBolts27 +
1¤4
turn20 +
1¤4
turnÐ
Structural CollarÐBolts Refer to Procedure
Crankshaft Main Bearing
Cap/Bedplate
ÐM8 Bolts 34 25 Ð
ÐM11 Bolts 81 60 Ð
Crankshaft Damper 136 100 Ð
Cylinder HeadÐBolts Refer to Procedure
Cylinder Head CoverÐ
Bolts12 Ð 105
DESCRIPTION N´mFt.
Lbs.In.
Lbs.
Drive Plate to Crankshaft 95 70 Ð
Engine Mount Bracket
RightÐBolts61 45 Ð
Engine Mounting Refer to Procedure
Exhaust Manifold to
Cylinder HeadÐBolts23 Ð 200
Exhaust Manifold Support
Bracket (Federal and
LEV)
ÐM8 Nut 28 Ð 250
ÐM10 Bolt 54 40 Ð
ÐM12 Bolt 95 70 Ð
Exhaust Manifold Support
Bracket (ULEV)54 40 Ð
Engine Torque Strut
Bracket to EngineÐBolts61 45 Ð
Powertrain Bending
StrutÐFront
ÐLong Bolts 101 75 Ð
ÐShort Bolts 61 45 Ð
Intake ManifoldÐBolts 12 Ð 105
Oil Filter Adaptor 80 60 Ð
Oil Filter 20 15 Ð
Oil PanÐBolts 12 Ð 105
Oil Pan DrainÐPlug 27 20 Ð
Oil Pump to Block 28 Ð 250
Oil Pump Cover
PlateÐBolts12 Ð 105
Oil Pump Pick-up
TubeÐBolt28 Ð 250
Oil Pump Relief
ValveÐCap41 30 Ð
PCV Valve 5.6 Ð 50
Rocker Arm ShaftÐBolts 28 Ð 250
Spark Plugs 28 Ð 250
Timing Belt CoverÐBolts 12 Ð 105
Timing Belt Tensioner
AssemblyÐBolts28 Ð 250
Water PumpÐBolts 12 Ð 105
PL2.0L SOHC ENGINE 9 - 71
SPECIFICATIONS (Continued)

DESCRIPTION AND 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.
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
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 the primary inputs that determine injec-
tor pulse width.
MODES OF OPERATION
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 35É the PCM will wait 44
seconds.
²If the coolant is over 50ÉF the PCM will wait 38
seconds.
²If the coolant is over 167ÉF the PCM will wait
11 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 0.1 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 - 22 FUEL SYSTEMPL

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)

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)

signal to the PCM, allowing engine starter operation.
The interlock switch is not adjustable.
Clutch Pedal Upstop Switch
With the clutch pedal at rest, the clutch pedal
upstop switch is closed, allowing speed control oper-
ation. When the clutch pedal is depressed, the upstop
switch opens and signals the PCM to cancel speed
control operation, and enter a modified engine cali-
bration schedule to improve driveability during gear-
to-gear shifts. The upstop switch is not adjustable.
CRANKSHAFT POSITION SENSORÐPCM
INPUT
DESCRIPTION
The crankshaft position sensor mounts to the front
of the engine block (Fig. 8).
OPERATION
The PCM determines what cylinder to fire from the
crankshaft position sensor input and the camshaft
position sensor input. The second crankshaft counter-
weight has two sets of four timing reference notches
including a 60 degree signature notch (Fig. 9). From
the crankshaft position sensor input the PCM deter-
mines engine speed and crankshaft angle (position).
The notches generate pulses from high to low in
the crankshaft position sensor output voltage. When
a metal portion of the counterweight aligns with the
crankshaft position sensor, the sensor output voltage
goes low (less than 0.5 volts). When a notch aligns
with the sensor, voltage goes high (5.0 volts). As a
group of notches pass under the sensor, the output
voltage switches from low (metal) to high (notch)
then back to low.If available, an oscilloscope can display the square
wave patterns of each voltage pulses. From the width
of the output voltage pulses, the PCM calculates
engine speed. The width of the pulses represent the
amount of time the output voltage stays high before
switching back to low. The period of time the sensor
output voltage stays high before switching back to
low is referred to as pulse width. The faster the
engine is operating, the smaller the pulse width on
the oscilloscope.
By counting the pulses and referencing the pulse
from the 60 degree signature notch, the PCM calcu-
lates crankshaft angle (position). In each group of
timing reference notches, the first notch represents
69 degrees before top dead center (BTDC). The sec-
ond notch represents 49 degrees BTDC. The third
notch represents 29 degrees. The last notch in each
set represents 9 degrees before top dead center
(TDC).
The timing reference notches are machined at 20É
increments. From the voltage pulse width the PCM
tells the difference between the timing reference
notches and the 60 degree signature notch. The 60
degree signature notch produces a longer pulse width
than the smaller timing reference notches. If the
camshaft position sensor input switches from high to
low when the 60 degree signature notch passes under
the crankshaft position sensor, the PCM knows cylin-
der number one is the next cylinder at TDC.
The PCM uses the Crankshaft Position sensor to
calculate the following: Engine RPM, TDC number 1
and 4, Ignition coil synchronization, Injection Syn-
chronization, Camshaft-to-crankshaft misalignment
where applicable (Timing belt skipped 1 tooth or
more diagnostic trouble code).
The PCM sends approximately 9 volts to the Hall-
effect sensor. This voltage is required to operate the
Hall-effect chip and the electronics inside the sensor.
A ground for the sensor is provided through the sen-
sor return circuit. The input to the PCM occurs on a
5 volt output reference circuit.
ENGINE COOLANT TEMPERATURE SENSORÐ
PCM INPUT
DESCRIPTION
The coolant sensor threads into the rear of the cyl-
inder head, next to the camshaft position sensor (Fig.
10). New sensors have sealant applied to the threads.
The ECT Sensor is a Negative Thermal Coefficient
(NTC), dual range Sensor. The resistance of the ECT
Sensor changes as coolant temperature changes. This
results in different input voltages to the PCM. The
PCM also uses the ECT Sensor input to operate the
low and high speed radiator cooling fans.
Fig. 8 Crankshaft Position Sensor
14 - 30 FUEL SYSTEMPL
DESCRIPTION AND OPERATION (Continued)