2000 DODGE NEON cooling

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

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)

(5) Install the wiring harness into the clips on the
side of the air cleaner box.
(6) Install air cleaner element on to throttle body
and push towards the throttle body and past lip in
air cleaner box bottom (Fig. 45).
(7) Install air duct.
(8) Install lid and tighten screws.
AIR CLEANER ELEMENT
REMOVAL
(1) Remove 5 screws from air cleaner element box
lid.(2) Remove lid from air cleaner box.
(3) Pull air cleaner up and out of air cleaner box.
INSTALLATION
(1) Install air cleaner element on to throttle body
and push towards the throttle body and past lip in
air cleaner box bottom (Fig. 46).
(2) Install lid and tighten screws.
ENGINE COOLANT TEMPERATURE SENSOR
The engine coolant temperature sensor threads
into the rear of the cylinder head (Fig. 47).
REMOVAL
(1) With the engine cold, drain coolant until level
drops below cylinder head. Refer to the Cooling Sys-
tem section.
(2) Disconnect coolant sensor electrical connector.
(3) Remove coolant sensor.
INSTALLATION
(1) Install coolant sensor. Tighten sensor to 18
N´m (165 in. lbs.) torque.
(2) Attach electrical connector to sensor.
(3) Fill cooling system. Refer to the Cooling Sys-
tem section.
VEHICLE SPEED SENSOR
The vehicle speed sensor is located in the transmis-
sion extension housing (Fig. 48) or (Fig. 49).
REMOVAL
(1) Disconnect electrical connector from sensor.
(2) Remove the sensor mounting bolt.
Fig. 44 Air Cleaner Box
Fig. 45 Air Cleaner Box Lip
1 ± LIP
Fig. 46 Air Cleaner Element
1 ± LIP
PLFUEL SYSTEM 14 - 47
REMOVAL AND INSTALLATION (Continued)

reduces the power required to drive the pump and
holds down temperature build-up.
When steering conditions exceed maximum pres-
sure requirements, such as when the wheels are
turned against the stops, the pressure built up in the
steering gear exerts pressure on the spring end of the
flow control valve. The high pressure lifts the relief
valve ball from its seat and allows oil to flow through
a trigger orifice located in the outlet fitting. This
reduces pressure on the spring end of the flow con-
trol valve which then opens and allows the oil to
return to the intake side of the pump. This action
limits maximum pressure output of the pump to a
safe level.
Under normal power steering pump operating con-
ditions, pressure requirements of the pump are below
maximum, causing the pressure relief valve to
remain closed.
POWER STEERING FLUID RESERVOIR
The power steering fluid reservoir is mounted on
the power steering pump using 3 bolts (Fig. 1). It
stores fluid for the power steering system.
The power steering fluid reservoir is considered an
integral part of the power steering pump and is not
serviced separately.
SERVICE PROCEDURES
POWER STEERING PUMP INITIAL OPERATION
CAUTION: The fluid level should be checked with
engine off to prevent injury from moving compo-
nents. Use only MoparTPower Steering Fluid. Do
not use automatic transmission fluid. Do not over-
fill.
Wipe the filler cap clean, then check the fluid level.
The dipstick should indicateCOLDwhen the fluid is
at normal temperature, approximately 21ÉC to 27ÉC
(70ÉF to 80ÉF).
(1) Fill the power steering fluid reservoir to the
proper level and let the fluid settle for at least two
minutes.
(2) Start the engine and let run for a few seconds,
then turn the engine off.
(3) Add fluid if necessary. Repeat the above proce-
dure until the fluid level remains constant after run-
ning the engine.
(4) Raise the front wheels off the ground.
(5) Start the engine. Slowly turn the steering
wheel right and left, lightly contacting the wheel
stops.
(6) Add power steering fluid if necessary.
(7) Lower the vehicle and turn the steering wheel
slowly from lock to lock.(8) Stop the engine. Check the fluid level and refill
as required.
(9) If the fluid is extremely foamy, allow the vehi-
cle to stand a few minutes and repeat the above pro-
cedure.
REMOVAL AND INSTALLATION
SERVICE WARNINGS AND CAUTIONS
WARNING: POWER STEERING FLUID, ENGINE
PARTS AND EXHAUST SYSTEM MAY BE
EXTREMELY HOT IF ENGINE HAS BEEN RUNNING.
DO NOT START ENGINE WITH ANY LOOSE OR DIS-
CONNECTED HOSES. DO NOT ALLOW HOSES TO
TOUCH HOT EXHAUST MANIFOLD OR CATALYST.
WARNING: FLUID LEVEL SHOULD BE CHECKED
WITH THE ENGINE OFF TO PREVENT PERSONAL
INJURY FROM MOVING PARTS.
CAUTION: When the system is open, cap all open
ends of the hoses, power steering pump fittings or
power steering gear ports to prevent entry of for-
eign material into the components.
NOTE: Do not use any type of automatic transmis-
sion fluid in the power steering system.
POWER STEERING PUMP
NOTE: Before proceeding with this removal and
installation procedure, review SERVICE WARNINGS
AND CAUTIONS at the beginning of REMOVAL AND
INSTALLATION in this section.
REMOVAL
(1) Remove battery cable from the negative post on
the battery.
(2) Siphon as much fluid as possible from the
power steering fluid reservoir.
(3) Remove the power steering pump drive belt
from the power steering pump pulley. Refer to
ACCESSORY DRIVE BELTS in the COOLING SYS-
TEM service manual group for the required removal
and installation procedure.
(4) Remove the hose clamp securing the return
hose to the power steering fluid reservoir. Slide the
hose off the end of the reservoir fitting. (Fig. 2).
(5) Back out the tube nut securing the power
steering fluid pressure hose to the power steering
pump and remove the hose from the pump (Fig. 2).
PLSTEERING 19 - 17
DESCRIPTION AND OPERATION (Continued)

SORY DRIVE BELTS in the COOLING SYSTEM
service manual group for the required removal and
installation procedure.
(6) Using a lint free towel, wipe clean all open
power steering hose ends and power steering pump
fittings.
(7) Install a new O-ring on the end of the power
steering pressure hose. Lubricate the O-ring using
clean power steering fluid.
(8) Attach the power steering fluid pressure hose
to the pressure fitting on the lower end of the power
steering pump (Fig. 2). Thread the tube nut securing
the power steering fluid pressure hose into the power
steering pump pressure fitting. Tighten the tube nut
to at torque of 34 N´m (25 ft. lbs.).
(9) Slide the power steering fluid return hose onto
the fluid reservoir fitting (Fig. 2). Position the hose
clamp so it is installed on the hose past the bead
formed into the fluid reservoir fitting.
(10) Perform the POWER STEERING PUMP INI-
TIAL OPERATION service procedure found in this
section of this group to properly fill and bleed the
power steering system.
(11) Check for leaks.
DISASSEMBLY AND ASSEMBLY
POWER STEERING PUMP (PULLEY)
The only serviceable part of the power steering
pump is the pulley. The following procedure is for the
removal and installation of the pulley from the
pump.
The power steering pump must be removed from
the vehicle for power steering pump pulley service.
Refer to POWER STEERING PUMP in REMOVAL
AND INSTALLATION for the required procedure.
CAUTION: Use care when removing and installing
the power steering pump pulley. It is made of plas-
tic composite, except for the center shank. The spe-
cial tools are to be used in the shank area only as
described in the following procedure.
DISASSEMBLY
CAUTION: Do not hammer on the power steering
pump pulley or shaft to remove the power steering
pump pulley. This will damage the pulley and the
power steering pump.
(1) Install Puller, Special Tool C-4333, or an equiv-
alent, on the steering pump pulley as shown (Fig. 5).
Tighten the puller screw drive and remove the pulley
from the power steering pump shaft.NOTE: Replace the power steering pump pulley if it
is cracked or loose.
(2) Remove the puller from the power steering
pump pulley.
ASSEMBLY
(1) Place the power steering pump pulley squarely
on end of the power steering pump shaft. Mount
Installer, Special Tool C-4063, or an equivalent, in
the internal threads of the power steering pump
shaft and against power steering pump pulley (Fig.
6).
Fig. 5 Pulley Removal
1 ± PULLEY
2 ± C-4333
3 ± POWER STEERING PUMP
Fig. 6 Pulley Installation
1 ± C-4063
2 ± PULLEY
3 ± POWER STEERING PUMP
PLSTEERING 19 - 19
REMOVAL AND INSTALLATION (Continued)

GENERAL INFORMATION
IN VEHICLE SERVICE
The following components are serviceable in the
vehicle without transaxle removal:
²Valve Body Assembly
²Converter Clutch Solenoid
²Governor
²Vehicle Speed Sensor & Pinion
²Park/Neutral & Back-up Lamp Switch
²Transfer Gears and Transfer Shaft
²Low/Reverse Servo
²Kickdown Servo
²Accumulator
FLUID REQUIREMENTS
NOTE: The transmission and differential have a
common oil sump with an opening between the
two.
TRANSMISSION/DIFFERENTIAL
MopartATF+4 (Automatic Transmission Fluid
Type 9602) is required in this transaxle. Substitute
fluids must meet fluid specification MS-9602.
FLUID ADDITIVES
Chrysler Corporation strongly recommends against
the addition of any fluids to the transmission, other
than those automatic transmission fluids listed
above. Exceptions to this policy are the use of special
dyes to aid in detecting fluid leaks.
Various ªspecialº additives and supplements exist
that claim to improve shift feel/quality and converter
clutch operation, inhibit overheating, oxidation, var-
nish and sludge. These claims have not been sup-
ported to Chrysler's satisfaction and these additives
must not be used. The use of transmission ªsealersº
should also be avoided, since they may adversely
affect the integrity of tranmission seals.
DESCRIPTION AND OPERATION
31TH GENERAL INFORMATION
NOTE: Safety goggles should be worn at all times
when working on these transaxles.
This transaxle combines torque converter, three
speed transmission, final drive gearing, and differen-
tial into a front wheel drive system.
NOTE: Transaxle operation requirements are differ-
ent for each vehicle and engine combination. Some
internal parts will be different to provide for this.Therefore, when replacing parts, refer to the seven
digit part number stamped on rear of the transaxle
oil pan flange.
Within this transaxle, there are three primary
areas:
(1) Main center line plus valve body.
(2) Transfer shaft center line (includes governor
and parking sprag).
(3) Differential center line.
Center distances between the main rotating parts
in these three areas are held precise to maintain a
low noise level.
The torque converter, transaxle area, and differen-
tial are housed in an integral aluminum die casting.
The differential oil sump is common with the
transaxle sump. Separate filling of the differen-
tial is NOT necessary.
The torque converter is attached to the crankshaft
through a flexible driving plate. Cooling of the con-
verter is accomplished by circulating the transaxle
fluid through a remote cooler. There are two types of
coolers used. An oil-to-water type cooler located in
the radiator side tank and/or an oil-to-air heat
exchanger. The torque converter assembly is a sealed
unit that cannot be disassembled.
The transaxle fluid is filtered by an internal filter
attached to the lower side of the valve body assembly.
Engine torque is transmitted to the torque con-
verter and then through the input shaft to multiple-
disc clutches in the transaxle. The power flow
depends on the application of the clutches and bands.
Refer to Elements in Use Chart in Diagnosis and
Tests section.
The transaxle consists of:
²Two multiple-disc clutches
²An overrunning clutch
²Two servos
²A hydraulic accumulator
²Two bands
²Two planetary gear sets
This provides three forward ratios and a reverse
ratio. The common sun gear of the planetary gear
sets is connected to the front clutch by a driving
shell. The driving shell is splined to the sun gear and
front clutch retainer. The hydraulic system consists
of an oil pump and a single valve body which con-
tains all of the valves except the governor valves.
The transaxle sump and differential sump are both
vented through the dipstick. Output torque from the
main center line is delivered through helical gears to
the transfer shaft. This gear set is a factor in the
transaxle final drive (axle) ratio. The shaft also car-
ries the governor and parking sprag. An integral heli-
cal gear on the transfer shaft drives the differential
ring gear.
PLTRANSAXLE 21 - 55

CONDITION POSSIBLE CAUSES CORRECTION
BUZZING NOISE 1. Fluid Level Low 1. Add fluid and check for leaks.
2. Shift Cable Misassembled. 2. Route cable away from engine and bell
housing.
3. Valve Body Misassembled. 3. Remove, disassemble, inspect valve
body. Reassemble correctly if necessary.
Replace assembly if valves or springs are
damaged. Check for loose bolts or screws.
4. Pump Passages Leaking 4. Check pump for porous casting, scores
on mating surfaces and excess rotor
clearance. Repair as required. Loose pump
bolts.
5. Cooling System Cooler Plugged. 5. Flow check cooler circuit. Repair as
needed.
6. Overrunning Clutch Damaged. 6. Replace clutch.
SLIPS IN REVERSE ONLY 1. Fluid Level Low. 1. Add fluid and check for leaks.
2. Gearshift Linkage Misadjusted. 2. Adjust linkage.
3. Rear Band Misadjusted. 3. Adjust band.
4. Rear Band Worn. 4. Replace as required.
5. Hydraulic Pressure Too Low. 5. Perform hydraulic pressure tests to
determine cause.
6. Rear Servo Leaking. 6. Air pressure check clutch-servo operation
and repair as required.
7. Band Linkage Binding. 7. Inspect and repair as required.
SLIPS IN FORWARD
DRIVE RANGES1. Fluid Level Low. 1. Add fluid and check for leaks.
2. Fluid Foaming. 2. Check for high oil level, bad pump
gasket or seals, dirt between pump halves
and loose pump bolts. Replace pump if
necessary.
3. Throttle Linkage Misadjusted. 3. Adjust linkage.
4. Gearshift Linkage Misadjusted. 4. Adjust linkage.
5. Rear Clutch Worn. 5. Inspect and replace as needed.
6. Low Hydraulic Pressure Due to
Worn Pump, Incorrect Control
Pressure Adjustments, Valve Body
Warpage or Malfunction, Sticking
Governor, Leaking Seal Rings,
Clutch Seals Leaking, Servo Leaks,
Clogged Filter or Cooler Lines6. Perform hydraulic and air pressure tests
to determine cause.
7. Rear Clutch Malfunction, Leaking
Seals or Worn Plates.7. Air pressure check clutch-servo operation
and repair as required.
8. Overrunning Clutch Worn, Not
Holding (Slips in 1 Only).8. Replace Clutch.
SLIPS IN LOW GEAR ªDº
ONLY, BUT NOT IN 1
POSITIONOverrunning Clutch Faulty. Replace overrunning clutch.
PLTRANSAXLE 21 - 63
DIAGNOSIS AND TESTING (Continued)