2000 DODGE NEON low oil pressure

LOW AND REVERSE SERVO (REAR)
Direct air pressure into LOW/REVERSE SERVO
APPLY passage. Operation of servo is indicated by a
tightening of rear band. Spring tension on servo pis-
ton should release the band.
If clutches and servos operate properly, no upshift
indicates that a malfunction exists in the valve body.
FLUID LEAKAGE-TRANSAXLE TORQUE
CONVERTER HOUSING AREA
(1) Check for source of leakage.
(2) Since fluid leakage near the torque converter
area may be from an engine oil leak, the area should
be checked closely. Factory fill fluid is dyed red and,
therefore, can be distinguished from engine oil.
(3) Prior to removing the transaxle, perform the
following checks:
(4) When leakage is determined to originate from
the transaxle, check fluid level prior to removal of
the transaxle and torque converter.
(5) High oil level can result in oil leakage out the
vent in the dipstick. If the fluid level is high, adjust
to proper level.
(6) After performing this operation, inspect for
leakage. If a leak persists, perform the following
operation on the vehicle. This will determine if the
torque converter or transaxle is leaking.
TORQUE CONVERTER LEAKAGE
Possible sources of torque converter leakage are:
²Torque converter weld leaks at the outside diam-
eter (peripheral) weld
²Torque converter hub weld
²Torque converter impeller shell cracked adjacent
to hub
²At drive lug welds
NOTE: Hub weld is inside and not visible. Do not
attempt to repair. Replace torque converter.
BRAKE TRANSMISSION SHIFT INTERLOCK
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. Refer to Brake Transmission Interlock
Removal and Installation or Adjustment in this
Group.
SERVICE PROCEDURES
TRANSAXLE FLUID AND FILTER SERVICE
NOTE: Refer to Group 0, Lubrication and Mainte-
nance, or the vehicle owner's manual, for the rec-
ommended maintenance (fluid/filter change)
intervals for this transaxle.
NOTE: Only fluids of the type labeled MoparT
ATF+4 (Automatic Transmission Fluid) Type 9602
should be used. A filter change should be made at
the time of the transmission oil change. The magnet
(on the inside of the oil pan) should also be cleaned
with a clean, dry cloth.
NOTE: If the transaxle is disassembled for any rea-
son, the fluid and filter should be changed.
FLUID/FILTER SERVICE (RECOMMENDED)
(1) Raise vehicle on a hoist (See Lubrication,
Group 0). Place a drain container with a large open-
ing, under transaxle oil pan.
(2) Loosen pan bolts and tap the pan at one corner
to break it loose allowing fluid to drain, then remove
the oil pan.
(3) Install a new filter and o-ring on bottom of the
valve body and tighten retaining screws to 5 N´m (40
in. lbs.).
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.
21 - 70 TRANSAXLEPL
DIAGNOSIS AND TESTING (Continued)

FLUSHING COOLERS AND TUBES
When a transaxle failure has contaminated the
fluid, the transaxle oil cooler(s) must be flushed (both
radiator and remote). The cooler bypass valve in the
transaxle must be replaced also. The torque con-
verter must also be replaced with an exchange unit.
This will ensure that metal particles or sludged oil
are not later transferred back into the reconditioned
(or replaced) transaxle.
The recommended procedure for flushing the cool-
ers and tubes is to use Tool 6906A Cooler Flusher.
WARNING: WEAR PROTECTIVE EYEWEAR THAT
MEETS THE REQUIREMENTS OF OSHA AND ANSI
Z87.1±1968. WEAR STANDARD INDUSTRIAL RUB-
BER GLOVES.
KEEP LIT CIGARETTES, SPARKS, FLAMES, AND
OTHER IGNITION SOURCES AWAY FROM THE
AREA TO PREVENT THE IGNITION OF COMBUSTI-
BLE LIQUIDS AND GASES. KEEP A CLASS (B) FIRE
EXTINGUISHER IN THE AREA WHERE THE
FLUSHER WILL BE USED.
KEEP THE AREA WELL VENTILATED.
DO NOT LET FLUSHING SOLVENT COME IN CON-
TACT WITH YOUR EYES OR SKIN: IF EYE CONTAM-
INATION OCCURS, FLUSH EYES WITH WATER FOR
15 TO 20 SECONDS. REMOVE CONTAMINATED
CLOTHING AND WASH AFFECTED SKIN WITH
SOAP AND WATER. SEEK MEDICAL ATTENTION.
COOLER FLUSH USING TOOL 6906A
(1) Remove cover plate filler plug on Tool 6906A.
Fill reservoir 1/2 to 3/4 full of fresh flushing solution.
Flushing solvents are petroleum based solutions gen-
erally used to clean automatic transmission compo-
nents.DO NOTuse solvents containing acids, water,
gasoline, or any other corrosive liquids.
(2) Reinstall filler plug on Tool 6906A.
(3) Verify pump power switch is turned OFF. Con-
nect red alligator clip to positive (+) battery post.
Connect black (-) alligator clip to a good ground.
(4) Disconnect the cooler lines at the transmission.
NOTE: When flushing transmission cooler and
lines, ALWAYS reverse flush.
(5) Connect the BLUE pressure line to the OUT-
LET (From) cooler line.
(6) Connect the CLEAR return line to the INLET
(To) cooler line
(7) Turn pump ON for two to three minutes to
flush cooler(s) and lines. Monitor pressure readingsand clear return lines. Pressure readings should sta-
bilize below 20 psi. for vehicles equipped with a sin-
gle cooler and 30 psi. for vehicles equipped with dual
coolers. If flow is intermittent or exceeds these pres-
sures, replace cooler.
(8) Turn pump OFF.
(9) Disconnect CLEAR suction line from reservoir
at cover plate. Disconnect CLEAR return line at
cover plate, and place it in a drain pan.
(10) Turn pump ON for 30 seconds to purge flush-
ing solution from cooler and lines. Turn pump OFF.
(11) Place CLEAR suction line into a one quart
container of MopartATF+4 (Automatic Transmission
Fluid) Type 9602.
(12) Turn pump ON until all transmission fluid is
removed from the one quart container and lines. This
purges any residual cleaning solvent from the trans-
mission cooler and lines. Turn pump OFF.
(13) Disconnect alligator clips from battery. Recon-
nect flusher lines to cover plate, and remove flushing
adapters from cooler lines.
OIL PUMP VOLUME CHECK
After the new or repaired transmission has been
installed, fill to the proper level with MopartATF+4
(Automatic Transmission Fluid) Type 9602. The vol-
ume should be checked using the following proce-
dure:
(1) Disconnect theFrom coolerline at the trans-
mission and place a collecting container under the
disconnected line.
CAUTION: With the fluid set at the proper level,
fluid collection should not exceed (1) quart or inter-
nal damage to the transmission may occur.
(2) Run the engineat curb idle speed, with the
shift selector in neutral.
(3) If fluid flow is intermittent or it takes more
than 20 seconds to collect one quart of ATF, discon-
nect theTo Coolerline at the transaxle.
(4) Refill the transaxle to proper level and recheck
pump volume.
(5) If flow is found to be within acceptable limits,
replace the cooler. Then fill transmission to the
proper level, using MopartATF+4 (Automatic Trans-
mission Fluid) Type 9602.
(6) If fluid flow is still found to be inadequate,
check the line pressure using the Transaxle Hydrau-
lic Pressure Test procedure.
21 - 72 TRANSAXLEPL
SERVICE PROCEDURES (Continued)

PARK/NEUTRAL STARTING AND BACK-UP
LAMP SWITCH
TEST
The park/neutral starting switch is the center ter-
minal of the three terminal switch. It provides
ground for the starter solenoid circuit through the
selector lever in PARK and NEUTRAL positions only.
(1) To test switch, remove wiring connector from
switch and test for continuity between center pin of
switch and transaxle case. Continuity should exist
only when transaxle is in PARK or NEUTRAL.
(2) Check gearshift cable adjustment before replac-
ing a switch that tests bad.
REMOVAL
(1) Unscrew switch from transaxle case allowing
fluid to drain into a container. Move selector lever to
PARK, then to NEUTRAL position, and inspect to see
the switch operating lever fingers are centered in
switch opening.
INSTALLATION
(1) Screw the switch with a new seal into tran-
saxle case and tighten to 33 N´m (24 ft. lbs.). Retest
switch with the test lamp.
(2) Add fluid to transaxle to bring up to proper
level.
(3) The back-up lamp switch circuit is through the
two outside terminals of the three terminal switch.
(4) To test switch, remove wiring connector from
switch and test for continuity between the two out-
side pins.
(5) Continuity should exist only with transaxle in
REVERSE position.
(6) No continuity should exist from either pin to
the case.
TRANSAXLE AND TORQUE CONVERTER
REMOVAL
(1) Raise hood.
(2) Disconnect both battery cables, remove battery
hold down clamp and bolt, and remove battery.
(3) Remove air cleaner/throttle body assy. (Fig. 45)
as follows:
(a) Disconnect proportional purge solenoid (PPS)
and crankcase vent hose from throttle body.
(b) Disconnect the Throttle Position Sensor
(TPS) and Idle Air Control (IAC) connectors.
(c) Remove mounting bolt and nut (Fig. 45) and
partially remove air cleaner assembly.
(d) Disconnect accelerator, transaxle kickdown,
and speed control (if equipped) cables after the
assy. is removed from position. Remove air cleaner
assembly from vehicle.(4) Remove battery tray from bracket.
(5) Disconnect torque converter clutch solenoid and
neutral safety/back-up lamp switch connectors.
(6) Disconnect and plug transaxle oil cooler lines
(Fig. 46).
(7) Disconnect shifter cable from shift lever and
remove from bracket (Fig. 47). Secure cable out of the
way.
Fig. 45 Air Cleaner Assembly Removal/Installation
1 ± AIR CLEANER ASSY.
2 ± THROTTLE BODY DUCT
Fig. 46 Transaxle Oil Cooler Lines
1 ± RETURN
2 ± CLAMPS
3 ± PRESSURE
21 - 84 TRANSAXLEPL
REMOVAL AND INSTALLATION (Continued)

CLEANING AND INSPECTION
VALVE BODY
Allow all parts to soak a few minutes in a suitable
clean solvent. Wash thoroughly and blow dry with
compressed air. Be sure all passages are clean and
free from obstructions.
Inspect manual and throttle valve operating levers
and shafts for being bent, worn or loose. If a lever is
loose on its shaft, it should be replaced. Do not
attempt to straighten bent levers.
Inspect all mating surfaces for burrs, nicks and
scratches. Minor blemishes may be removed with cro-
cus cloth, using only a very light pressure. Using a
straightedge, inspect all mating surfaces for warpage
or distortion. Slight distortion may be corrected,
using a surface plate. Be sure all metering holes in
steel plate are open. Using a penlight, inspect bores
in valve body for scores, scratches, pits, and irregu-
larities.
Inspect all valve springs for distortion and col-
lapsed coils. Inspect all valves and plugs for burrs,
nicks, and scores. Small nicks and scores may be
removed with crocus cloth, providing extreme care is
taken not to round off sharp edges. The sharpness of
these edges is vitally important. It prevents foreign
matter from lodging between valve and valve body.
This reduces the possibility of sticking. Inspect all
valves and plugs for freedom of operation in valve
body bores.
When bores, valves, and plugs are clean and dry,
the valves and plugs should fall freely in the bores.
The valve body bores do not change their dimensions
with use. Therefore, a valve body that was function-
ing properly when vehicle was new, will operate cor-
rectly if it is properly and thoroughly cleaned. There
is no need to replace a valve body unless it is dam-
aged in handling.
ADJUSTMENTS
GEARSHIFT CABLE
Normal operation of the Park/Neutral Position
Switch provides a quick check to confirm proper link-
age adjustment. The engine starter should only oper-
ate when the transaxle shift lever is in the PARK (P)
or NEUTRAL (N) positions.
If the engine starts in any other gear position, or
the vehicle rolls when the shifter is in gated PARK
(P), a gearshift cable adjustment is necessary.
ADJUSTMENT
(1) Loosen set screw and remove knob from shifter
handle (Fig. 214).(2) Remove the center console assembly as shown
in (Fig. 215).
(3)Adjust gearshift cable as follows:
(a) Place gearshift lever in the PARK (P) posi-
tion.
(b) Loosen shift cable adjustment screw (Fig.
216).
(c) Move transaxle manual lever to the PARK.
Verify transaxle is in PARK by attempting to roll
vehicle in either direction.
Fig. 214 Gearshift Knob Removal/Installation
1 ± SHIFTER KNOB
2 ± SET SCREW
Fig. 215 Center Console Removal/Installation
1 ± CONSOLE
2 ± SCREW (4)
3 ± SCREW (2)
PLTRANSAXLE 21 - 135

SPECIFICATIONS
31TH AUTOMATIC TRANSAXLE
Type .........Automatic three speed with torque
converter and integral differential
Torque Converter Diameter...... 241millimeters
(9.48 in.)
OilType .....................MopartATF+4
(Automatic Transmission Fluid) Type 9602
Cooling Method.... Water Heat Exchanger and/or
air to oil heat exchanger
Lubrication . . . Pump (internal-external gear-type)
Transmission Gear Ratios
First Gear............................2.69
Second Gear...........................1.55
Third Gear............................1.00
Reverse Gear..........................2.10
Band Adjustment
KickdownÐBacked Off From 8 N²m
(72 in. lbs.).................... 21/4Turns
Low-ReverseÐBacked Off From 5 N²m
(41 in. lbs.).................... 31/2Turns
Clutch Pack Clearances
Front Clutch (Not Adjustable)......1.27-2.79mm
(0.050-0.110 in.)
Rear Clutch.......0.71-1.10mm (0.028-0.043 in.)
End Play
Input Shaft........0.19±1.50 mm (.008±.060 in.)
Front Clutch Retainer...........0.76±2.69 mm
(.030±.106 in.)
Front Carrier.......0.89±1.45 mm (.007±.057 in.)
Front Annulus Gear . . 0.09±0.50 mm (.0035±.020 in.)
Planet Pinion.......0.15±0.59 mm (.006±.023 in.)
Reverse Drum......0.76±3.36 mm (.030±.132 in.)
Oil Pump Clearances
Outer Gear To Pocket...........0.045-0.141mm
(0.0018-0.0056 in.)
Outer Gear Side Clearance.......0.020-0.046mm
(0.0008-0.0018 in.)
Inner Gear Side Clearance.......0.020-0.046mm
(0.0008-0.0018 in.)
Tapered Roller Bearing Settings
Differential Assembly . . 6 to 12 in. lbs. Drag Torque
Output Hub.......... 0to3in.lbs. Drag Torque
Transfer Shaft.......0.002 to 0.010 in. End Play
Overall Drag At Output
Hub ............. 3to16in.lbs. Drag TorqueThrust Washers
Reaction Shaft Support (No. 1).....1.55±1.60 mm
(.061±.063 in.)
Rear Clutch Retainer (No. 2)......1.55±1.60 mm
(.061±.063 in.)
Output Shaft (No. 3) (Select)......1.98±2.03 mm
(.077±.080 in.)
Output Shaft (No. 3) (Select)......2.15±2.22 mm
(.085±.087 in.)
Output Shaft (No. 3) (Select)......2.34±2.41 mm
(.092±.095 in.)
Front Annulus (No. 4)............2.95±3.05 mm
(.116±.120 in.)
Front Carrier (Nos. 5&6).........1.22±1.28 mm
(.0948±.050 in.)
Sun Gear-Front (No. 7)...........0.85±0.91 mm
(.033±.036 in.)
Sun Gear-Rear (No. 8)...........0.85±0.91 mm
(.033±.036 in.)
Rear Carrier (Nos. 9&10).........1.22±1.28 mm
(.0948±.050 in.)
Rev. Drum (No. 11) . . 1.55±1.60 mm (.061±.063 in.)
31TH TRANSAXLE TORQUE SPECIFICATIONS
DESCRIPTION TORQUE
Bell Housing Cover Bolts.... 12N´m(105 in. lbs.)
Cooler Line Clamps.......... 2N´m(18in.lbs.)
Diff. Bear. Ret. To Case Bolt . . 34 N´m (300 in. lbs.)
Diff. Cover To Case Bolt..... 19N´m(165 in. lbs.)
Exten. Hous. To Case Bolt . . . 28 N´m (250 in. lbs.)
Drive Plate To Crankshaft
Bolts................... 95N´m(70ft.lbs.)
Drive Plate To Torque Conv.
Bolts................... 88N´m(65ft.lbs.)
Fluid Filter Screw........... 5N´m(45in.lbs.)
Governor Counterweight
Screw................. 28N´m(250 in. lbs.)
Governor To Support Bolt...... 7N´m(60in.lbs.)
Kickdown Band Adj. Lock Nut . . 47 N´m (35 ft. lbs.)
Left Motor Mount Bolts....... 54N´m(40ft.lbs.)
Manual Cable To Trans.
Case Bolt.............. 28N´m(250 in. lbs.)
Manual Control Lever Screw . . 12 N´m (105 in. lbs.)
Oil Pan To Trans. Case
Screw................. 19N´m(165 in. lbs.)
Output Gear Strap Bolts...... 23N´m(17ft.lbs.)
Output Shaft Nut......... 271N´m(200 ft. lbs.)
Park/Neutral Switch......... 34N´m(25ft.lbs.)
Pressure Check Plug......... 5N´m(45in.lbs.)
Pump To Case Bolts........ 31N´m(275 in. lbs.)
Reaction Shaft Assembly
Bolt................... 28N´m(250 in. lbs.)
Rear Cover To Case Screw . . . 19 N´m (165 in. lbs.)
Reverse Band Adj. Lock Nut . . 14 N´m (125 in. lbs.)
21 - 150 TRANSAXLEPL

(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)

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)

The PCM is programmed to maintain the optimum
air/fuel ratio of 14.7 to 1. This is done by making
short term corrections in the fuel injector pulse width
based on the O2S output. The programmed memory
acts as a self calibration tool that the engine control-
ler uses to compensate for variations in engine spec-
ifications, sensor tolerances and engine fatigue over
the life span of the engine. By monitoring the actual
air-fuel ratio with the O2S (short term) and multiply-
ing that with the program long-term (adaptive) mem-
ory and comparing that to the limit, it can be
determined whether it will pass an emissions test. If
a malfunction occurs such that the PCM cannot
maintain the optimum A/F ratio, then the MIL will
be illuminated.
Monitor OperationÐFuel systems monitors do
not have a pre-test because they are continuously
running monitors. Therefore, the PCM constantly
monitors Short Term Compensation and Long Term
Adaptive memory.
Lean: If at anytime during a lean engine operation,
short term compensation multiplied by long term
adaptive exceeds a certain percentage for an
extended period, the PCM sets a Fuel System Lean
Fault for that trip and a Freeze Frame is entered.
Rich: If at anytime during a rich operation, Short
Term Compensation multiplied by Long Term Adap-
tive is less than a predetermined value, the PCM
checks the Purge Free Cells.
Purge Free Cells are values placed in Adaptive
Memory cells when the EVAP Purge Solenoid is OFF.
Two, three or four Purge Free cells are used. One cor-
responds to an Adaptive Memory cell at idle, the
other to a cell that is off-idle. For example, if a Purge
Free cell is labeled PFC1, it would hold the value for
Adaptive Memory cell C1 under non-purge condi-
tions.
If all Purge Free Cells are less than a certain per-
centage, and the Adaptive Memory factor is less than
a certain percentage, the PCM sets a Fuel System
Rich fault for that trip and a Freeze Frame is
entered.
The Fuel Monitor is a two trip monitor. The PCM
records engine data in Freeze Frame upon setting of
the first fault, or maturing code. When the fuel mon-
itor fails on a second consecutive trip, the code is
matured and the MIL is illuminated. The stored
Freeze Frame data is still from the first fault.
In order for the PCM to extinguish the MIL, the
Fuel Monitor must pass in a Similar Condition Win-
dow. The similar conditions relate to RPM and load.
The engine must be within a predetermined percent-
age of both RPM and load when the monitor runs to
count a good trip. As with all DTCs, three good tripsare required to extinguish the MIL and 40 warm up
cycles are required to erase the DTC. If the engine
does not run in a Similar Conditions Window, the
Task Manager extinguishes the MIL after 80 good
trips.
Enabling ConditionsÐThe following conditions
must be met to operate the fuel control monitor:
²PCM not in fuel crank mode (engine running)
²PCM in Closed Loop fuel control
²Fuel system updating Long Term Adaptive
²Fuel level above 15% of capacity
²Fuel level below 85% of capacity
Pending ConditionsÐThe Fuel Control Monitor
does not operate if the MIL is illuminated for any of
the following:
²Misfire Monitor
²Upstream O2S
²EVAP Purge Solenoid Electrical PCM Self Test
Fault
²Camshaft or Crankshaft Position Sensor
²Fuel Injectors
²Ignition Coil Primary
²Throttle Position (TPS) Sensor
²Engine Coolant Temperature (ECT) Sensor
²Manifold Absolute Pressure (MAP) Sensor
²Idle Air Control (IAC)
²5V Output Too Low
²EGR Monitor
²EGR Solenoid Circuit
²Vehicle Speed Sensor
²Oxygen Sensor Monitor
²Oxygen Sensor Heater Monitor
²Oxygen Sensor Electrical
²Idle Speed Rationality
²Intake Air Temperature
SuspendÐThe Task Manager will suspend
maturing a Fuel System fault if any of the following
are present:
²Oxygen Sensor Response, Priority 1
²O2 Heater, Priority 1
²Misfire Monitor, Priority 2
EVAPORATIVE EMISSIONS MONITOR
LEAK DETECTION PUMP MONITORÐThe
leak detection assembly incorporates two primary
functions: it must detect a leak in the evaporative
system and seal the evaporative system so the leak
detection test can be run.
The primary components within the assembly are:
A three port solenoid that activates both of the func-
tions listed above; a pump which contains a switch,
two check valves and a spring/diaphragm, a canister
vent valve (CVV) seal which contains a spring loaded
vent seal valve.
PLEMISSION CONTROL SYSTEMS 25 - 17
DESCRIPTION AND OPERATION (Continued)