2000 DODGE NEON width

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)

HEATED OXYGEN SENSOR (O2 SENSOR)Ð
PCM INPUT
DESCRIPTION
The upstream oxygen sensor threads into the out-
let flange of the exhaust manifold (Fig. 11).
The downstream heated oxygen sensor threads into
the system depending on emission package (Fig. 12).
Federal package the O2s is mounted after the cata-
lytic convertor, LEV package the O2s is mounted mid
catalytic convertor, ULEV package is mounted
between the catalytic convertor (Fig. 13).
OPERATION
The O2 sensors produce voltages from 0 to 1 volt,
depending upon the oxygen content of the exhaust
gas in the exhaust manifold (Fig. 14). When a large
amount of oxygen is present (caused by a lean air/
fuel mixture), the sensors produce a voltage below
450 mv. When there is a lesser amount present (rich
air/fuel mixture) it produces a voltage above 450 mv.
By monitoring the oxygen content and converting it
to electrical voltage, the sensors act as a rich- lean
switch.
The oxygen sensors are equipped with a heating
element that keeps the sensors at proper operating
temperature during all operating modes. Maintaining
correct sensor temperature at all times allows the
system to enter into closed loop operation sooner.
Also, it allows the system to remain in closed loop
operation during periods of extended idle.
In Closed Loop operation the PCM monitors the O2
sensor input (along with other inputs) and adjusts
the injector pulse width accordingly. During Open
Loop operation the PCM ignores the O2 sensor input.
The PCM adjusts injector pulse width based on pre-
programmed (fixed) values and inputs from other
sensors.
The Automatic Shutdown (ASD) relay supplies bat-
tery voltage to both the upstream and downstream
heated oxygen sensors. The oxygen sensors are
equipped with a heating element. The heating ele-
ments reduce the time required for the sensors to
reach operating temperature.
UPSTREAM OXYGEN SENSOR 1/1
The input from the upstream heated oxygen sensor
tells the PCM the oxygen content of the exhaust gas.
Based on this input, the PCM fine tunes the air-fuel
ratio by adjusting injector pulse width.
The sensor input switches from 0 to 1 volt, depend-
ing upon the oxygen content of the exhaust gas in
the exhaust manifold. When a large amount of oxy-
gen is present (caused by a lean air-fuel mixture), the
sensor produces voltage as low as 0.1 volt. When
there is a lesser amount of oxygen present (rich air-
fuel mixture) the sensor produces a voltage as high
as 1.0 volt. By monitoring the oxygen content and
converting it to electrical voltage, the sensor acts as
a rich-lean switch.
The heating element in the sensor provides heat to
the sensor ceramic element. Heating the sensor
allows the system to enter into closed loop operation
sooner. Also, it allows the system to remain in closed
loop operation during periods of extended idle.
In Closed Loop, the PCM adjusts injector pulse
width based on the upstream heated oxygen sensor
input along with other inputs. In Open Loop, the
PCM adjusts injector pulse width based on prepro-
Fig. 11 Upstream Heated Oxygen Sensor 1/1
1 ± OXYGEN SENSORS
2 ± EXHAUST MANIFOLD
Fig. 12 Downstream Heated Oxygen Sensor 1/2
14 - 32 FUEL SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

IGNITION CIRCUIT SENSEÐPCM INPUT
OPERATION
The ignition circuit sense input tells the Power-
train Control Module (PCM) the ignition switch has
energized the ignition circuit.
Battery voltage is also supplied to the PCM
through the Ignition Switch when the ignition is in
the RUN or START position. This is called the9igni-
tion senseº circuit and is used to ªwake upº the PCM.
Voltage on the ignition input can be as low as 6 volts
and the PCM will still function. Voltage is supplied to
this circuit to power the 8-volt regulator and to allow
the PCM to perform fuel, ignition and emissions con-
trol functions. The battery voltage on this line is sup-
plied to the 8-volt regulator which then passes on a
power-up supply to the 5-volt regulator.
INLET AIR TEMPERATURE SENSORÐPCM
INPUT
DESCRIPTION
The IAT sensor attaches to the intake air duct
(Fig. 15).
The IAT Sensor is a Negative Temperature Coeffi-
cient (NTC) Sensor that provides information to the
PCM regarding the temperature of the air entering
the intake manifold.
OPERATION
Intake Air Temperature
The inlet air temperature sensor replaces the
intake air temperature sensor and the battery tem-
perature sensor. The PCM uses the information from
the inlet air temperature sensor to determine valuesto use as an intake air temperature sensor and a bat-
tery temperature sensor.
The Intake Air Temperature (IAT) sensor value is
used by the PCM to determine air density.
The PCM uses this information to calculate:
²Injector pulse width
²Adjustment of ignition timing (to prevent spark
knock at high intake air temperatures)
Battery Temperature
The inlet air temperature sensor replaces the
intake air temperature sensor and the battery tem-
perature sensor. The PCM uses the information from
the inlet air temperature sensor to determine values
for the PCM to use as an intake air temperature sen-
sor and a battery temperature sensor.
The battery temperature information along with
data from monitored line voltage (B+), is used by the
PCM to vary the battery charging rate. System volt-
age will be higher at colder temperatures and is
gradually reduced at warmer temperatures.
The battery temperature information is also used
for OBD II diagnostics. Certain faults and OBD II
monitors are either enabled or disabled depending
upon the battery temperature sensor input (example:
disable purge and EGR, enable LDP). Most OBD II
monitors are disabled below 20ÉF.
KNOCK SENSORÐPCM INPUT
DESCRIPTION
The knock sensor threads into the side of the cyl-
inder block (Fig. 16). The knock sensor is designed to
detect engine vibration that is caused by detonation.
Fig. 15 Inlet Air Temperature Sensor
Fig. 16 Knock Sensor
14 - 34 FUEL SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

position of the throttle blade changes, the resistance
of the TPS changes.
OPERATION
The PCM supplies approximately 5 volts DC to the
TPS. The TPS output voltage (input signal to the
powertrain control module) represents throttle blade
position. The TPS output voltage to the PCM varies
from approximately 0.35 to 1.03 volts at minimum
throttle opening (idle) to a maximum of 3.1 to 4.0
volts at wide open throttle.
Along with inputs from other sensors, the PCM
uses the TPS input to determine current engine oper-
ating conditions. The PCM also adjusts fuel injector
pulse width and ignition timing based on these
inputs.
When the TPS indicates a voltage that is too high,
too low or not believable, the PCM sets a DTC. When
the DTC is set, the MIL is illuminated and the PCM
moves into limp-in mode. Limp-in for the TPS is
divided into three categories:
²Idle
²Part-throttle
²Wide open throttle (WOT)
VEHICLE SPEED SIGNAL (VSS)ÐPCM INPUT
DESCRIPTION
The PCM requires the VSS to be able to control
the following programs:
²Speed Control
²IAC motor (during deceleration)
²Injection pulse width (during deceleration)
²OBD II diagnostics
²PCM mileage EEPROM
²Road speed shutdown
²Speedometer/Odometer (bused message)NOTE: Road Speed Shutdown is the PCM shutting
off fuel injectors above a preset vehicle speed.
The vehicle speed sensor is located in the transmis-
sion extension housing (Fig. 21) and (Fig. 22).
OPERATION
The vehicle speed sensor on 3 speed automatic and
manual transaxle vehicles is a Hall-effect sensor.
This sensor is mechanically driven by a pinion gear
that is in mesh with the right axle drive shaft. The
hall-effect sensor switches a 5 volt signal sent from
the PCM from a ground to an open circuit.
Fig. 20 Throttle Position Sensor and Idle Air Control
Motor
Fig. 21 Vehicle Speed SensorÐAutomatic
Transmission
1 ± TRANSAXLE EXTENSION HOUSING
2 ± VEHICLE SPEED SENSOR
Fig. 22 Vehicle Speed SensorÐManual
Transmission
1 ± TRANSAXLE
2 ± SPEED SENSOR
3 ± SPEED SENSOR RETAINING BOLT
PLFUEL SYSTEM 14 - 37
DESCRIPTION AND OPERATION (Continued)

DATA LINK CONNECTOR
DESCRIPTION
The data link connector is located inside the vehi-
cle, under the instrument panel, left of the steering
column (Fig. 25).
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.
FUEL INJECTORSÐPCM OUTPUT
DESCRIPTION
OPERATION
The 2.0L engine uses electrically operated top feed
fuel injectors (Fig. 26). The Automatic Shutdown
(ASD) relay supplies battery voltage to the fuel injec-
tors. The PCM controls the ground path for each
injector in sequence. By switching the ground paths
on and off, the PCM fine-tunes injector pulse width.
Injector pulse width refers to the amount of time an
injector operates.
The PCM determines injector synchronization from
the camshaft position sensor and crankshaft position
sensor inputs. The PCM grounds the ASD and fuel
pump relays after receiving the camshaft position
sensor and crankshaft position sensor inputs.
The PCM energizes the injectors in a sequential
order during all engine operating conditions except
start-up. For the first injector pulse width during
start-up, all injectors are energized at the same time.
Once the PCM determines crankshaft position, it
begins energizing the injectors in sequence.
IGNITION COILÐPCM OUTPUT
DESCRIPTION
The coil assembly consists of 2 coils molded
together. The coil assembly is mounted over the valve
cover (Fig. 27).
OPERATION
High tension leads route to each cylinder from the
coil. The coil fires two spark plugs every power
Fig. 24 Idle Air Control MotorÐTypical
Fig. 25 Data Link Connector
1 ± DATA LINK CONNECTOR
Fig. 26 Fuel Injector
1 ± FUEL INJECTOR
2 ± NOZZLE
3 ± TOP (FUEL ENTRY)
14 - 40 FUEL SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

CLEANING AND INSPECTION
CLEANING TIRES
Remove the protective coating on the tires before
delivery of a vehicle. This coating may cause deteri-
oration of the tires.
To remove the protective coating, apply warm
water and let it soak for a few minutes. Afterwards,
scrub the coating away with a soft bristle brush.Steam cleaning may also be used to remove the coat-
ing.
NOTE: DO NOT use gasoline, mineral oil, oil-based
solvent or a wire brush for cleaning.
SPECIFICATIONS
TIRE SPECIFICATIONS
The following guide should help you understand the tire designations:
P Passenger car tire (or ªTº for temporary-use tire).
185 Nominal width of tire in millimeters.
70 Tire height-to-width ratio.
R Radial-ply tire (or ªDº for bias-ply tire).
14 Nominal rim diameter in inches.
Do not install smaller than minimum size tires shown on the tire inflation placard on the vehicle.
PLTIRES AND WHEELS 22 - 9

sections help hold the tire in position on the wheel
until the vehicle can be brought to a safe stop.
Cast aluminum wheels require special balance
weights to fit on the thicker flange of the rim and
special wheel clamps for the alignment equipment.
The wheel studs and nuts are designed for specific
wheel applications and must be replaced with equiv-
alent parts. Do not use replacement parts of lesser
quality or of a substitute design. All aluminum
wheels use wheel nuts with an enlarged nose. This
enlarged nose is necessary to ensure proper retention
of the wheels.
Vehicles that are equipped with lock-on wheel cov-
ers use large nose wheel nuts. The wheel nuts are
externally threaded so that the wheel covers can be
attached to the wheel nuts.
WHEEL COVER (LOCK-ON)
This vehicle uses a lock-on type wheel cover (Fig.
3) on certain models.
The wheel cover is attached to the wheel using the
5 nuts located in the wheel cover (Fig. 3). The nuts in
the wheel cover thread onto a special externally
threaded wheel nut (Fig. 4) to retain the wheel cover
to the wheel.
The wheel cover retaining nut (Fig. 3) is retained
in the wheel cover and will stay on the wheel cover
when un-threaded from the wheel nut. If required,
the retaining nut can be removed from the wheel
cover and replaced as a separate part of the wheel
cover.
The lock-on wheel cover can not be removed from
the wheel until all 5 wheel cover retaining nuts areun-threaded from the wheel nuts. Then the lock-on
wheel cover can be removed by hand from the wheel.DIAGNOSIS AND TESTING
WHEEL INSPECTION
Inspect wheels for:
²Excessive run out
²Dents or cracks
²Damaged wheel lug nut holes
²Air Leaks from any area or surface of the rim
NOTE: Do not attempt to repair a wheel by ham-
mering, heating or welding.
If a wheel is damaged an original equipment
replacement wheel should be used. When obtaining
replacement wheels, they should be equivalent in
load carrying capacity. The diameter, width, offset,
Fig. 2 Safety Rim
1 ± TIRE
2 ± WELL
3 ± SAFETY HUMPS
4 ± FLANGE
Fig. 3 Wheel Cover And Retaining Nut
1 ± WHEEL COVER RETAINING NUTS
2 ± TIRE
3 ± WHEEL
4 ± LOCK-ON WHEEL COVER
Fig. 4 Wheel Nut And Wheel Cover Retaining Nut
1 ± WHEEL NUT
2 ± EXTERNAL THREADS
3 ± LOCK-ON WHEEL COVER RETAINING NUT
PLTIRES AND WHEELS 22 - 11
DESCRIPTION AND OPERATION (Continued)

MONITORED SYSTEMS
DESCRIPTION
There are new electronic circuit monitors that
check fuel, emission, engine and ignition perfor-
mance. These monitors use information from various
sensor circuits to indicate the overall operation of the
fuel, engine, ignition and emission systems and thus
the emissions performance of the vehicle.
The fuel, engine, ignition and emission systems
monitors do not indicate a specific component prob-
lem. They do indicate that there is an implied prob-
lem within one of the systems and that a specific
problem must be diagnosed.
If any of these monitors detect a problem affecting
vehicle emissions, the Malfunction Indicator (Check
Engine) Lamp will be illuminated. These monitors
generate Diagnostic Trouble Codes that can be dis-
played with the check engine lamp or a scan tool.
The following is a list of the monitored systems:
²EGR Monitor
²Misfire Monitor
²Fuel System Monitor
²Evaporative Emissions Monitor
Following is a description of each system monitor,
and its DTC.
Refer to the appropriate Powertrain Diagnos-
tics Procedures manual for diagnostic proce-
dures.
EGR MONITOR
The Powertrain Control Module (PCM) performs
an on-board diagnostic check of the EGR system.
The EGR system consists of two main components:
a vacuum solenoid back pressure transducer and a
vacuum operated valve. The EGR monitor is used to
test whether the EGR system is operating within
specifications. The diagnostic check activates only
during selected engine/driving conditions. When the
conditions are met, the EGR is turned off (solenoid
energized) and the O2S compensation control is mon-
itored. Turning off the EGR shifts the air fuel (A/F)
ratio in the lean direction. Oxygen sensor voltage
then indicates increased oxygen in the exhaust. Con-
sequently, Short Term Compensation shifts to rich
(increased injector pulse width). By monitoring the
shift, the PCM can indirectly monitor the EGR sys-
tem. While this test does not directly measure the
operation of the EGR system, it can be inferred from
the shift in the O2S data whether the EGR system is
operating correctly. Because the O2S is being used,
the O2S test must pass its test before the EGR test.
Enabling ConditionsÐ
²Engine Temperature
²Engine Run Time
²Engine RPM²MAP Sensor
²TPS
²Vehicle Speed
²Short Term Compensation
Pending ConditionsÐThe EGR Monitor does
not run when any of the following example faults
have illuminated the MIL:
²Misfire
²Oxygen Sensor Monitor
²Oxygen Sensor Heater Monitor
²Fuel System Rich/Lean
²Limp in for MAP, TPS or ECT
²Vehicle Speed Sensor
²Cam or Crank Sensor
²EGR Electrical
²EVAP Electrical
²Fuel Injector
²Ignition Coil
²Idle Speed
²Engine Coolant Temperature (ECT)
²MAP Sensor
²Intake Air Temperature (IAT)
Conflict ConditionsÐThe EGR Monitor typi-
cally does not run if any of the following conditions
are present:
²Fuel System Monitor
²Purge Monitor
²Catalyst Monitor
²Low Fuel Level
²High Altitude
²Low Ambient Air Temperature
The EGR Monitor does not run if any of the follow-
ing example DTCs are present:
²Misfire Monitor, Priority 2
²Upstream Oxygen Sensor Heater, Priority 1
²Fuel System Monitor, Priority 2
²Oxygen Sensor Monitor, Priority 1
MISFIRE MONITOR
Excessive engine misfire results in increased cata-
lyst temperature and causes an increase in HC emis-
sions. Severe misfires could cause catalyst damage.
To prevent catalytic convertor damage, the PCM
monitors engine misfire.
The Powertrain Control Module (PCM) monitors
for misfire during most engine operating conditions
(positive torque) by looking at changes in the crank-
shaft speed. If a misfire occurs the speed of the
crankshaft will vary more than normal.
OBD II regulations for misfire monitoring require
two different tests for misfire. The first is a Catalyst
Damage level of misfire test. The second is for emis-
sions greater than 1.5 times the Federal Tailpipe
(FTP) standards. The tests are monitored by two dif-
ferent counters. These counters are:
PLEMISSION CONTROL SYSTEMS 25 - 15
DESCRIPTION AND OPERATION (Continued)