brake DODGE NEON 2000 Service Repair Manual

(9) Verify that shifter is in gated ªPARKº.
(10) Install the cable core end to the plastic cam of
the shifter mechanism. Snap the shifter/ignition
interlock cable end fitting into the groove in the gear-
shift mechanism as shown in (Fig. 32).
(11)Adjust interlock cable/system as follows:
If interlock cable is being replaced, it will come with
an adjustment pin. Remove the pin from the cable
and allow the cable to ªself-adjustº. Lock cable
adjustment by pressing down on the adjuster lock
until bottomed at the cable housing. If interlock cable
is being re-used, no pin will be provided. Pry up on
cable adjuster lock to release and allow cable to ªself-
adjustº. Lock cable adjustment by pressing down on
the adjuster lock until bottomed at the cable housing.
(12)Connect battery negative cable and ver-
ify interlock system operation as follows:
(13) Install shifter bezel (Fig. 31).
(14) Install center console assembly (Fig. 30).
(15) Install gearshift knob and tighten set screw to
2 N´m (15 in. lbs.) torque (Fig. 29).
INTERLOCK MECHANISM
REMOVAL
(1) Remove the steering column lower cover (Fig.
39).
(2) Remove the steering column upper and lower
shrouds (Fig. 40).
(3) Turn the ignition key to the ªOFFº or ªON/
RUNº position (Fig. 41).
(4) Grasp the interlock cable and connector firmly.
Remove the interlock cable (Fig. 42).(5) Remove the two interlock mechanism-to-steer-
ing column attaching screws (Fig. 43). Remove the
interlock housing.INSTALLATION
(1) Position the interlock housing at steering col-
umn. Install the two interlock mechanism-to-steering
column attaching screws. Torque screws to 3 N´m (21
in. lbs.).
(2) Snap the interlock cable into the housing.
ACTION EXPECTED RESPONSE
1. Turn key to the ªOFFº
position.1. Shifter CAN be shifted
out of park.
2. Turn key to the
9ON/RUNº position.2. Shifter CANNOT be
shifted out of park.
3. Turn key to the
ªON/RUNº position and
depress the brake pedal.3. Shifter CAN be shifted
out of park.
4. Leave shifter in any
gear and try to return key
to the ªLOCKº or9ACCº
position.4. Key cannot be
returned to the ªLOCKº or
ªACCº position.
5. Return shifter to
ªPARKº and try to remove
the key.5. Key can be removed
(after returning to ªLOCKº
position).
6. With the key removed,
try to shift out of ªPARKº.6. Shifter cannot be
shifted out of ªPARKº.
NOTE: Any failure to meet these expected
responses requires system adjustment or repair.
Fig. 39 Steering Column Lower Cover
1 ± LOWER COVER
Fig. 40 Steering Column Shrouds
1 ± UPPER SHROUD
2 ± LOWER SHROUD
21 - 82 TRANSAXLEPL
REMOVAL AND INSTALLATION (Continued)

BRAKE TRANSMISSION SHIFT INTERLOCK
SYSTEM
VERIFICATION
The following chart describes the normal operation
of the Brake Transmission Shift Interlock (BTSI) sys-
tem. If the ªexpected responseº differs from the vehi-
cle's response, then system repair and/or adjustment
is necessary.
ADJUSTMENT
(1) Loosen set screw and remove knob from shifter
handle (Fig. 219).
(2) Remove the center console assembly as shown
in (Fig. 220).
(3) Remove shifter bezel (Fig. 221).
(4)Adjust interlock cable/system as follows:
Pry up on cable adjuster lock to release and allow
cable to ªself-adjustº. Lock cable adjustment by press-
ing down on the adjuster lock until bottomed at the
cable housing.
(5) Verify correct system operation. Refer to verifi-
cation procedure.
(6) Install shifter bezel (Fig. 221).
(7) Install center console assembly (Fig. 220).
(8) Install gearshift knob and tighten set screw to
2 N´m (15 in. lbs.) torque (Fig. 219).
ACTION EXPECTED RESPONSE
1. Turn key to the ªOFFº
position.1. Shifter CAN be shifted
out of park.
2. Turn key to the
9ON/RUNº position.2. Shifter CANNOT be
shifted out of park.
3. Turn key to the
ªON/RUNº position and
depress the brake pedal.3. Shifter CAN be shifted
out of park.
4. Leave shifter in any
gear and try to return key
to the ªLOCKº or9ACCº
position.4. Key cannot be
returned to the ªLOCKº or
ªACCº position.
5. Return shifter to
ªPARKº and try to remove
the key.5. Key can be removed
(after returning to ªLOCKº
position).
6. With the key removed,
try to shift out of ªPARKº.6. Shifter cannot be
shifted out of ªPARKº.
NOTE: Any failure to meet these expected
responses requires system adjustment or repair.
Fig. 219 Gearshift Knob Removal/Installation
1 ± SHIFTER KNOB
2 ± SET SCREW
Fig. 220 Center Console Removal/Installation
1 ± CONSOLE
2 ± SCREW (4)
3 ± SCREW (2)
PLTRANSAXLE 21 - 137
ADJUSTMENTS (Continued)

TIRES AND WHEELS
TABLE OF CONTENTS
page page
TIRES................................... 1WHEELS................................ 10
TIRES
TABLE OF CONTENTS
page page
DESCRIPTION AND OPERATION
TIRE...................................1
RADIAL-PLY TIRES........................2
SPARE TIRE±TEMPORARY..................3
REPLACEMENT TIRES.....................3
DIAGNOSIS AND TESTING
TREAD WEAR INDICATORS.................3
TIRE WEAR PATTERNS.....................4
TIRE NOISE OR VIBRATION.................4
VEHICLE LEAD DIAGNOSIS AND
CORRECTION..........................4
SERVICE PROCEDURES
PRESSURE GAUGES......................6TIRE INFLATION PRESSURES...............6
TIRE PRESSURE FOR HIGH SPEED
OPERATION............................6
TIRE AND WHEEL ROTATION................6
REPAIRING TIRE LEAKS....................7
TIRE AND WHEEL MATCH MOUNTING.........7
CLEANING AND INSPECTION
CLEANING TIRES.........................9
SPECIFICATIONS
TIRE SPECIFICATIONS.....................9
DESCRIPTION AND OPERATION
TIRE
Tires are designed and engineered for each specific
vehicle (Fig. 1). They provide the best overall perfor-
mance for normal operation. The ride and handling
characteristics match the vehicle's requirements.
With proper care they will give excellent reliability,
traction, skid resistance, and tread life.
Driving habits have more effect on tire life than
any other factor. Careful drivers will obtain, in most
cases, much greater mileage than severe use or care-
less drivers. A few of the driving habits which will
shorten the life of any tire are:²Rapid acceleration
²Severe application of brakes
²High-speed driving
²Taking turns at excessive speeds
²Striking curbs and other obstacles
²Operating vehicle with over or under inflated
tire pressures
Radial ply tires are more prone to irregular tread
wear. It is important to follow the tire rotation inter-
val shown in the section on Tire Rotation. This will
help to achieve a greater tread-life potential.
PLTIRES AND WHEELS 22 - 1

signals when the vehicle is equipped with Anti-Lock
Brakes.
The use of tires from different manufactures on the
same vehicle is NOT recommended. The proper tire
pressure should be maintained on all four tires.
SPARE TIRE±TEMPORARY
The temporary spare tire is designed for emer-
gency use only. The original tire should be repaired
or replaced at the first opportunity, then reinstalled.
Do not exceed speeds of 50 M. P. H. when using the
temporary spare tire. Refer to Owner's Manual for
complete details.
REPLACEMENT TIRES
The original equipment tires provide a proper bal-
ance of many characteristics such as:
²Ride
²Noise
²Handling
²Durability
²Tread life
²Traction
²Rolling resistance
²Speed capabilityIt is recommend that tires equivalent to the origi-
nal equipment tires be used when replacement is
needed.
Failure to use equivalent replacement tires may
adversely affect the safety and handling of the vehi-
cle.
The use of oversize tires may cause interference
with vehicle components. Under extremes of suspen-
sion and steering travel, interference with vehicle
components may cause tire damage.
WARNING: FAILURE TO EQUIP THE VEHICLE WITH
TIRES HAVING ADEQUATE SPEED CAPABILITY
CAN RESULT IN SUDDEN TIRE FAILURE.
DIAGNOSIS AND TESTING
TREAD WEAR INDICATORS
Tread wear indicators are molded into the bottom
of the tread grooves. When tread depth is 1.6 mm
(1/16 in.), the tread wear indicators will appear as a
13 mm (1/2 in.) band (Fig. 3).
Tire replacement is necessary when indicators
appear in two or more grooves or if localized balding
occurs.
Fig. 2 Tire Identification
Fig. 3 Tread Wear Indicators
1 ± TREAD ACCEPTABLE
2 ± TREAD UNACCEPTABLE
3 ± WEAR INDICATOR
PLTIRES AND WHEELS 22 - 3
DESCRIPTION AND OPERATION (Continued)

pilot hole and bolt circle of the wheel should be the
same as the original wheel.
WARNING: FAILURE TO USE EQUIVALENT
REPLACEMENT WHEELS MAY ADVERSELY AFFECT
THE SAFETY AND HANDLING OF THE VEHICLE.
USED WHEELS ARE NOT RECOMMENDED. THE
SERVICE HISTORY OF THE WHEEL MAY HAVE
INCLUDED SEVERE TREATMENT OR VERY HIGH
MILEAGE. THE RIM COULD FAIL WITHOUT WARN-
ING.
TIRE AND WHEEL RUNOUT
NOTE: Runout should always be measured off the
vehicle and on a suitable balance machine.
Radial run out is the difference between the high
and low points on the outer edge of the tire or wheel.
Lateral run out is the total side±to±side wobble of
the tire or wheel.
Radial run out of more than 1.5 mm (.060 inch)
measured at the center line of the tread may cause
the vehicle to shake.
Lateral run out of more than 2.0 mm (.080 inch)
measured at the side of the tire as close to the tread
as possible may cause the vehicle to shake.
Sometimes radial run out can be reduced by relo-
cating the wheel and tire on the wheel studs (See
Method 1). If this does not reduce run out to an
acceptable level, the tire can be rotated on the wheel.
(See Method 2).
METHOD 1 (RELOCATE WHEEL ON HUB)
Check accuracy of the wheel mounting surface;
adjust wheel bearings.
Drive vehicle a short distance to eliminate tire flat
spotting from a parked position.
Verify all wheel nuts are tightened and properly
torqued in the correct sequence (Fig. 5).
Use run out gauge D-128-TR to determine run out
(Fig. 6).
Relocate the wheel on the mounting studs, two
studs over from the original position.
Retighten wheel nuts until all are properly
torqued. This will prevent brake distortion.
Check radial run out. If still excessive, mark tire
sidewall, wheel, and stud at point of maximum run
out (Fig. 7) and proceed to Method 2.
Fig. 5 Tightening Wheel Nuts
Fig. 6 Run Out Gauge
Fig. 7 Chalk Marking On Wheel, Tire And Stud
1 ± STUD
2 ± TIRE
3 ± CHALK MARK LOCATIONS
22 - 12 TIRES AND WHEELSPL
DIAGNOSIS AND TESTING (Continued)

(3) When flange on retaining nut is past the 2
retaining tabs on the wheel cover, remove retaining
nut from wheel cover by pushing or pulling from hole
in wheel cover.
INSTALL
(1) Install retaining nut in hole of wheel cover
with retaining nut flange positioned under the large
retaining flange (Fig. 13).
(2) Push on hex of retaining nut forcing the retain-
ing nut flange past the 2 small retaining tabs in
wheel cover.
TIRE AND WHEEL ASSEMBLY
CAST WHEEL
REMOVAL
(1) Raise the vehicle. Refer to HOISTING in the
LUBRICATION AND MAINTENANCE section.
(2) Remove the wheel mounting nuts from the
studs.
(3) Remove the tire and wheel assembly from the
hub.
INSTALLATION
CAUTION: Installing the wheel mounting nuts with-
out having good metal-to-mental contact between
the back of the wheel and the hub mounted brake
disc or drum could cause the wheel to bind and
eventually cause loosening of the wheel mounting
nuts.
(1) Install the tire and wheel assembly on the hub
studs against the hub mounted brake disc or drum
using the hub pilot as a guide.
CAUTION: When installing the tire and wheel
assembly, never use oil or grease on studs or nuts.
(2) Install and lightly tighten the wheel mounting
nuts in the proper sequence (Fig. 14).
(3) Lower the vehicle.
(4) Progressively tighten the 5 wheel nuts in the
proper sequence until tightened to half of the speci-
fied torque (Fig. 14). Finally, tighten the wheel nuts
in the proper sequence to a torque of 135 N´m (100
ft. lbs.).
STEEL WHEEL
REMOVAL
(1) Raise the vehicle. Refer to HOISTING in the
LUBRICATION AND MAINTENANCE section.CAUTION: When removing the lock-on wheel cover,
do not attempt to pry the wheel cover off the wheel.
This can result in damage to the wheel cover. The
wheel cover is removed by unthreading the wheel
cover retaining nuts and pulling it off the wheel by
hand.
NOTE: When unthreading the lock-on wheel cover
retaining nuts (Fig. 15) from the wheel nuts it is rec-
ommended that a hand wrench be used and not an
impact wrench. Use of an impact wrench could
result in damage to the lock-on wheel cover retain-
ing nuts.
(2) Unthread the nuts attaching the wheel cover to
the wheel mounting nuts (Fig. 15).
Fig. 14 Tightening Wheel Nuts
Fig. 15 Wheel Cover Retaining Nuts
1 ± TIRE
2 ± VALVE STEM
3 ± LOCK-ON WHEEL COVER
4 ± WHEEL
5 ± WHEEL COVER RETAINING NUTS
22 - 16 TIRES AND WHEELSPL
REMOVAL AND INSTALLATION (Continued)

(3) Grasp the wheel cover and pull straight out-
ward. This will remove the wheel cover from the
wheel.
(4) Remove the wheel mounting nuts from the
studs (Fig. 16).
(5) Remove the tire and wheel assembly from the
hub.
INSTALLATION
CAUTION: Installing the wheel mounting nuts with-
out having good metal-to-mental contact between
the back of the wheel and the hub mounted brake
disc or drum could cause the wheel to bind and
eventually cause loosening of the wheel mounting
nuts.
(1) Install the tire and wheel assembly on the hub
studs against the hub mounted brake disc or drum
using the hub pilot as a guide.
CAUTION: When installing the tire and wheel
assembly, never use oil or grease on studs or nuts.
(2) Install and lightly tighten the wheel nuts in
the proper sequence (Fig. 17).
(3) Lower the vehicle.
(4) Progressively tighten the 5 wheel nuts in the
proper sequence until tightened to half of the speci-
fied torque (Fig. 17). Finally, tighten the wheel nutsin the proper sequence to a torque of 135 N´m (100
ft. lbs.).
(5) Align the valve notch in the wheel cover with
the valve stem on the wheel (Fig. 15). Align the
wheel cover retaining nuts with the externally
threaded wheel nuts.
(6) By hand, start to thread all 5 of the wheel
cover retaining nuts onto the externally threaded
wheel nuts.
NOTE: When tightening the wheel cover retaining
nuts it is recommended that a hand wrench be used
and not an impact wrench. Use of an impact wrench
could result in damage to the lock-on wheel cover
retaining nuts.
(7) Tighten each of the wheel cover retaining nuts.
If the retaining nut ªjumpsº a thread (slips), which is
an override feature of the retaining nut, retighten
the retaining nut to a point just prior to this occur-
ring. To avoid rattling of the wheel cover be sure all
five retaining nuts are correctly tightened.
SPECIFICATIONS
WHEEL SPECIFICATIONS
Wheel:
Wheel Mounting Stud Size...... M12x1.5mm
Wheel Mounting Nut Hex Size......... 19mm
Wheel Mounting Nut Torque..... 115±155 N´m
(85 to 115 ft. lbs.)
Fig. 16 Wheel Nuts
1 ± WHEEL
2 ± EXTERNALLY THREADED WHEEL NUTS
3 ± TIRE
Fig. 17 Wheel Nut Tightening Sequence
PLTIRES AND WHEELS 22 - 17
REMOVAL AND INSTALLATION (Continued)

(M) Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code was recorded.
P0456 Evap Leak Monitor Small Leak
Detected
P0460 Fuel Level Unit No Change Over
MilesNo movement of fuel level sender detected.
P0461 Fuel Level Unit No Changeover
TimeNo level of fuel level sender detected.
P0462 Fuel Level Sending Unit Volts Too
LowFuel level sensor input below acceptable voltage.
P0463 Fuel Level Sending Unit Volts Too
HighFuel level sensor input above acceptable voltage.
P0500 (M) No Vehicle Speed Sensor Signal No vehicle speed sensor signal detected during road
load conditions.
P0505 (M) Idle Air Control Motor Circuits Replace
P0522 Oil Pressure Sens Low Oil pressure sensor input below acceptable voltage.
P0523 Oil Pressure Sens High Oil pressure sensor input above acceptable voltage.
P0551 (M) Power Steering Switch Failure Incorrect input state detected for the power steering
switch circuit. PL: High pressure seen at high speed.
P0600 (M) PCM Failure SPI Communications No communication detected between co-processors in
the control module.
P0601 (M) Internal Controller Failure Internal control module fault condition (check sum)
detected.
P0604 Internal Trans Controller Transmission control module RAM self test fault
detected. -Aisin transmission.
P0605 Internal Trans Controller Transmission control module ROM self test fault
detected -Aisin transmission.
P0622 (G) Generator Field Not Switching
ProperlyAn open or shorted condition detected in the generator
field control circuit.
P0645 A/C Clutch Relay Circuit An open or shorted condition detected in the A/C clutch
relay control circuit.
P0700 (M) EATX Controller DTC Present This SBEC III or JTEC DTC indicates that the EATX or
Aisin controller has an active fault and has illuminated
the MIL via a CCD (EATX) or SCI (Aisin) message. The
specific fault must be acquired from the EATX via CCD
or from the Aisin via ISO-9141.
P0703 (M) Brake Switch Stuck Pressed or
ReleasedIncorrect input state detected in the brake switch circuit.
(Changed from P1595).
P0711 Trans Temp Sensor, No Temp Rise
After StartRelationship between the transmission temperature and
overdrive operation and/or TCC operation indicates a
failure of the Transmission Temperature Sensor. OBD II
Rationality.
P0712 Trans Temp Sensor Voltage Too
LowTransmission fluid temperature sensor input below
acceptable voltage.
P0713 Trans Temp Sensor Voltage Too
HighTransmission fluid temperature sensor input above
acceptable voltage.
P0720 Low Output SPD Sensor RPM,
Above 15 MPHThe relationship between the Output Shaft Speed
Sensor and vehicle speed is not within acceptable
limits.
25 - 10 EMISSION CONTROL SYSTEMSPL
DESCRIPTION AND OPERATION (Continued)

NOTE: Comprehensive component monitors are
continuous. Therefore, enabling conditions do not
apply.
Input RationalityÐWhile input signals to the
PCM are constantly being monitored for electrical
opens and shorts, they are also tested for rationality.
This means that the input signal is compared against
other inputs and information to see if it makes sense
under the current conditions.
PCM sensor inputs that are checked for rationality
include:
²Manifold Absolute Pressure (MAP) Sensor
²Oxygen Sensor (O2S)
²Engine Coolant Temperature (ECT) Sensor
²Camshaft Position (CMP) Sensor
²Vehicle Speed Sensor
²Crankshaft Position (CKP) Sensor
²Intake Air Temperature (IAT) Sensor
²Throttle Position (TPS) Sensor
²Ambient/Battery Temperature Sensors
²Power Steering Switch
²Oxygen Sensor Heater
²Engine Controller
²Brake Switch
²Leak Detection Pump Switch
²P/N Switch
²Trans Controls
Output FunctionalityÐPCM outputs are tested
for functionality in addition to testing for opens and
shorts. When the PCM provides a voltage to an out-
put component, it can verify that the command was
carried out by monitoring specific input signals for
expected changes. For example, when the PCM com-
mands the Idle Air Control (IAC) Motor to a specific
position under certain operating conditions, it expects
to see a specific (target) idle speed (RPM). If it does
not, it stores a DTC.
PCM outputs monitored for functionality include:
²Fuel Injectors
²Ignition Coils
²Torque Converter Clutch Solenoid
²Idle Air Control
²Purge Solenoid
²EGR Solenoid
²LDP Solenoid
²Radiator Fan Control
²Trans Controls
OXYGEN SENSOR (O2S) MONITOR
DESCRIPTIONÐEffective control of exhaust
emissions is achieved by an oxygen feedback system.
The most important element of the feedback system
is the O2S. The O2S is located in the exhaust path.
Once it reaches operating temperature 300É to 350ÉC
(572É to 662ÉF), the sensor generates a voltage that
is inversely proportional to the amount of oxygen inthe exhaust. When there is a large amount of oxygen
in the exhaust caused by a lean condition, the sensor
produces a low voltage, below 450 mV. When the oxy-
gen content is lower, caused by a rich condition, the
sensor produces a higher voltage, above 450mV.
The information obtained by the sensor is used to
calculate the fuel injector pulse width. This main-
tains a 14.7 to 1 air fuel (A/F) ratio. At this mixture
ratio, the catalyst works best to remove hydrocarbons
(HC), carbon monoxide (CO) and nitrous oxide (NOx)
from the exhaust.
The O2S is also the main sensing element for the
EGR, Catalyst and Fuel Monitors.
The O2S may fail in any or all of the following
manners:
²Slow response rate (Big Slope)
²Reduced output voltage (Half Cycle)
²Heater Performance
Slow Response Rate (Big Slope)ÐResponse
rate is the time required for the sensor to switch
from lean to rich signal output once it is exposed to a
richer than optimum A/F mixture or vice versa. As
the PCM adjusts the air/fuel ratio, the sensor must
be able to rapidly detect the change. As the sensor
ages, it could take longer to detect the changes in the
oxygen content of the exhaust gas. The rate of
change that an oxygen sensor experiences is called
'Big Slope'. The PCM checks the oxygen sensor volt-
age in increments of a few milliseconds.
Reduced Output Voltage (Half Cycle)ÐThe
output voltage of the O2S ranges from 0 to 1 volt. A
good sensor can easily generate any output voltage in
this range as it is exposed to different concentrations
of oxygen. To detect a shift in the A/F mixture (lean
or rich), the output voltage has to change beyond a
threshold value. A malfunctioning sensor could have
difficulty changing beyond the threshold value. Each
time the voltage signal surpasses the threshold, a
counter is incremented by one. This is called the Half
Cycle Counter.
Heater PerformanceÐThe heater is tested by a
separate monitor. Refer to the Oxygen Sensor Heater
Monitor.
OPERATIONÐAs the Oxygen Sensor signal
switches, the PCM monitors the half cycle and big
slope signals from the oxygen sensor. If during the
test neither counter reaches a predetermined value, a
malfunction is entered and a Freeze Frame is stored.
Only one counter reaching its predetermined value is
needed for the monitor to pass.
The Oxygen Sensor Monitor is a two trip monitor
that is tested only once per trip. When the Oxygen
Sensor fails the test in two consecutive trips, the
MIL is illuminated and a DTC is set. The MIL is
extinguished when the Oxygen Sensor monitor
passes in three consecutive trips. The DTC is erased
25 - 20 EMISSION CONTROL SYSTEMSPL
DESCRIPTION AND OPERATION (Continued)

Pending ConditionsÐ
²Misfire DTC
²Front Oxygen Sensor Response
²Front Oxygen Sensor Heater Monitor
²Front Oxygen Sensor Electrical
²Rear Oxygen Sensor Rationality (middle check)
²Rear Oxygen Sensor Heater Monitor
²Rear Oxygen Sensor Electrical
²Fuel System Monitor
²All TPS faults
²All MAP faults
²All ECT sensor faults
²Purge flow solenoid functionality
²Purge flow solenoid electrical
²All PCM self test faults
²All CMP and CKP sensor faults
²All injector and ignition electrical faults
²Idle Air Control (IAC) motor functionality
²Vehicle Speed Sensor
²Brake switch
²Intake air temperature
ConflictÐThe catalyst monitor does not run if
any of the following are conditions are present:
²EGR Monitor in progress
²Fuel system rich intrusive test in progress
²EVAP Monitor in progress
²Time since start is less than 60 seconds
²Low fuel level
²Low ambient air temperature
SuspendÐThe Task Manager does not mature a
catalyst fault if any of the following are present:
²Oxygen Sensor Monitor, Priority 1
²Upstream Oxygen Sensor Heater, Priority 1
²EGR Monitor, Priority 1
²EVAP Monitor, Priority 1
²Fuel System Monitor, Priority 2
²Misfire Monitor, Priority 2
NON-MONITORED CIRCUITS
OPERATION
The PCM does not monitor all circuits, systems
and conditions that could have malfunctions causing
driveability problems. However, problems with these
systems may cause the PCM to store diagnostic trou-
ble codes for other systems or components. For exam-
ple, a fuel pressure problem will not register a fault
directly, but could cause a rich/lean condition or mis-
fire. This could cause the PCM to store an oxygen
sensor or misfire diagnostic trouble code.
The major non-monitored circuits are listed below
along with examples of failures modes that do not
directly cause the PCM to set a DTC, but for a sys-
tem that is monitored.FUEL PRESSURE
The fuel pressure regulator controls fuel system
pressure. The PCM cannot detect a clogged fuel
pump inlet filter, clogged in-line fuel filter, or a
pinched fuel supply or return line. However, these
could result in a rich or lean condition causing the
PCM to store an oxygen sensor or fuel system diag-
nostic trouble code.
SECONDARY IGNITION CIRCUIT
The PCM cannot detect an inoperative ignition coil,
fouled or worn spark plugs, ignition cross firing, or
open spark plug cables.
CYLINDER COMPRESSION
The PCM cannot detect uneven, low, or high engine
cylinder compression.
EXHAUST SYSTEM
The PCM cannot detect a plugged, restricted or
leaking exhaust system. It may set a EGR or Fuel
system fault or O2S.
FUEL INJECTOR MECHANICAL MALFUNCTIONS
The PCM cannot determine if a fuel injector is
clogged, the needle is sticking or if the wrong injector
is installed. However, these could result in a rich or
lean condition causing the PCM to store a diagnostic
trouble code for either misfire, an oxygen sensor, or
the fuel system.
EXCESSIVE OIL CONSUMPTION
Although the PCM monitors engine exhaust oxygen
content when the system is in closed loop, it cannot
determine excessive oil consumption.
THROTTLE BODY AIR FLOW
The PCM cannot detect a clogged or restricted air
cleaner inlet or filter element.
VACUUM ASSIST
The PCM cannot detect leaks or restrictions in the
vacuum circuits of vacuum assisted engine control
system devices. However, these could cause the PCM
to store a MAP sensor diagnostic trouble code and
cause a high idle condition.
PCM SYSTEM GROUND
The PCM cannot determine a poor system ground.
However, one or more diagnostic trouble codes may
be generated as a result of this condition. The mod-
ule should be mounted to the body at all times, also
during diagnostic.
PLEMISSION CONTROL SYSTEMS 25 - 23
DESCRIPTION AND OPERATION (Continued)