1999 DODGE NEON Engine Coolant Temperature Sensor

(13) Inspect the air cleaner filter element. Replace
as necessary. Check the air induction system for
restrictions.
(14) Check the electrical connection at the knock
sensor (Fig. 64).
(15) Check the electrical connections at the cam-
shaft position sensor (Fig. 65) and engine coolant
temperature sensor (Fig. 66).
(16) Check the electrical connector at the Elec-
tronic EGR Transducer. Inspect the vacuum and back
pressure hoses at the solenoid and transducer for
leaks (Fig. 67).
(17) Inspect the electrical connections at the gen-
erator (Fig. 68). Check the generator belt for glazing
or damage.
Fig. 63 Starter Motor and Ground Strap
Fig. 64 Knock Sensor
Fig. 65 Camshaft Position Sensor
Fig. 66 Engine Coolant Temperature Sensor
Fig. 67 Electronic EGR Transducer
PLFUEL SYSTEM 14 - 43
DIAGNOSIS AND TESTING (Continued)

(7) Attach the other end of the jumper wire to
relay terminal 86. This activates the relay. The ohm-
meter should now show continuity between relay ter-
minals 87 and 30. The ohmmeter should not show
continuity between relay terminals 87A and 30.
(8) Disconnect jumper wires.
(9) Replace the relay if it did not pass the continu-
ity and resistance tests. If the relay passed the tests,
it operates properly. Check the remainder of the ASD
and fuel pump relay circuits. Refer to group 8W, Wir-
ing Diagrams.
CAMSHAFT AND CRANKSHAFT POSITION SENSOR
Refer to Group 8D, Ignition for Diagnosis and Test-
ing of Camshaft and Crankshaft Sensors.
ENGINE COOLANT TEMPERATURE SENSOR
(1) With the key off, disconnect wire harness con-
nector from coolant temperature sensor (Fig. 79) or
(Fig. 80).(2) Connect a high input impedance (digital) volt-
ohmmeter to terminals A and B (Fig. 81). The ohm-
meter should read as follows:
²Engine/Sensor at normal operating temperature
around 200ÉF should read approximately 700 to
1,000 ohms.
²Engine/Sensor at room temperature around 70ÉF
ohmmeter should read approximately 7,000 to 13,000
ohms.
(3) T
est the resistance of the wire harness between
the PCM 60-way connector terminal 28 and the sensor
harness connector. Also check for continuity between
PCM 60-way connector terminal 51 and the sensor har-
ness connector. Refer to Group 8W, Wiring diagrams for
circuit information. If the resistance is greater than 1
ohm, repair the wire harness as necessary.
HEATED OXYGEN SENSOR
Use an ohmmeter to test the heating element of
the oxygen sensors. Disconnect the electrical connec-
tor from each oxygen sensor. The white wires in the
sensor connector are the power and ground circuits
for the heater. Connect the ohmmeter test leads to
terminals of the white wires in the heated oxygen
sensor connector. Replace the heated oxygen sensor if
the resistance is not between 4 and 7 ohms.
IDLE AIR CONTROL (IAC) MOTOR TEST
To preform a complete test of IAC motor and its
circuitry, refer to DRB scan tool and the appropriate
Powertrain Diagnostics Procedures manual.
KNOCK SENSOR
The engine knock sensor is affected by a number of
factors. A few of these are: ignition timing, cylinder
pressure, fuel octane, etc. The knock sensor generates
an AC voltage whose amplitude increases with the
increase of engine knock. The knock sensor can be
tested with a digital voltmeter. The RMS voltage starts
Fig. 79 Engine Coolant Temperature Sensor
LocationÐSOHC
Fig. 80 Engine Coolant Temperature Sensor
LocationÐDOHC
Fig. 81 Engine Coolant Temperature Sensor
PLFUEL SYSTEM 14 - 47
DIAGNOSIS AND TESTING (Continued)

(3) Remove air cleaner element from front housing
(Fig. 106).
INSTALLATION
(1) Install air cleaner element into front housing.
(2) Rotate front of housing forward then lower into
place and locate tabs in slots. Fasten clasps on top of
air cleaner housing.
(3) Install air intake duct at air cleaner and intake
manifold.
ENGINE COOLANT TEMPERATURE SENSOR
The engine coolant temperature sensor threads
into the rear of the cylinder head (Fig. 107) or (Fig.
108).
REMOVAL
(1) With the engine cold, drain coolant until level
drops below cylinder head. Refer to Group 7, Cooling
System.
(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 Group 7, Cooling
System.
VEHICLE SPEED SENSOR
The vehicle speed sensor is located in the transmis-
sion extension housing (Fig. 109).
REMOVAL
(1) Disconnect electrical connector from sensor.
(2) Remove the sensor mounting bolt.
(3) Lift the sensor out of the transaxle extension
housing. Ensure the O-ring was removed with the
sensor.
Fig. 104 Air Intake Duct
Fig. 105 Removal/Installation of Air Inlet Duct
Fig. 106 Removal/Installation Air Cleaner Front
Housing and Element
Fig. 107 Engine Coolant Temperature SensorÐ
SOHC
14 - 56 FUEL SYSTEMPL
REMOVAL AND INSTALLATION (Continued)

INSTALLATION
The speed sensor gear meshes with a gear on the
output shaft.
(1) With O-ring in place, install sensor.
(2) Install mounting bolt.
(3) Connect electrical connector to sensor.
KNOCK SENSOR
For removal/installation procedures refer to Group
8D- Ignition System, Service Procedures.
SPECIFICATIONS
VECI LABEL
If anything differs between the specifications found
on the Vehicle Emission Control Information (VECI)
label and the following specifications, use specifica-
tions on VECI label. The VECI label is located in the
engine compartment.
TORQUE
DESCRIPTION TORQUE
Air Cleaner Wingnut..........1.5 N´m (15 in. lbs.)
Air Cleaner Mount. Stud-To-Thrott. Body .10 N´m (90
in. lbs.)
Crankshaft Position Sensor Mounting Bolts.8 N´m (70
in. lbs.)
Engine Coolant Temperature Sensor .18 N´m (165 in.
lbs.)
IAC Motor-To-Throttle Body Bolts .7 N´m (60 in. lbs.)
MAP/IAT Sensor..............2N´m(20in.lbs.)
MAP/IAT Sensor..............3N´m(30in.lbs.)
Oxygen Sensor...............28N´m(20ft.lbs.)
Powertrain Control Module (PCM) Mounting Screws.4
N´m (35 in. lbs.)
Throttle Cable Cover.........4.5 N´m (40 in. lbs.).
Throttle Body Mounting Bolts . .23 N´m (200 in. lbs.)
Throttle Position Sensor Mounting Screws .2 N´m (20
in. lbs.)
Vehicle Speed Sensor Mounting Bolt .2.2 N´m (20 in.
lbs.)
SPECIAL TOOLS
FUEL
Fig. 108 Engine Coolant Temperature SensorÐ
DOHCFig. 109 Vehicle Speed Sensor
Extractor C±4334Pressure Gauge Assembly C±4799±B
PLFUEL SYSTEM 14 - 57
REMOVAL AND INSTALLATION (Continued)

DIAGNOSTIC TROUBLE CODE DESCRIPTIONS
HEX
CODEGENERIC
SCAN
TOOL
CODEDRB SCAN TOOL
DISPLAYDESCRIPTION OF DIAGNOSTIC TROUBLE CODE
01 P0340 No Cam Signal at PCM No camshaft signal detected during engine cranking.
02 P0601 Internal Controller Failure PCM Internal fault condition detected.
05 P1682 Charging System Voltage
Too LowBattery voltage sense input below target charging during
engine operation. Also, no significant change detected in
battery voltage during active test of generator output
circuit.
06 P1594 Charging System Voltage
Too HighBattery voltage sense input above target charging
voltage during engine operation.
0A* P1388 Auto Shutdown Relay
Control CircuitAn open or shorted condition detected in the auto
shutdown relay circuit.
0B P0622 Generator Field Not
Switching ProperlyAn open or shorted condition detected in the generator
field control circuit.
0C P0743 Torque Converter Clutch
Soleniod/Trans Relay
CircuitsAn open or shorted condition detected in the torque
converter part throttle unlock solenoid control circuit (3
speed auto RH trans. only).
0E P1491 Rad Fan Control Relay
CircuitAn open or shorted condition detected in the low speed
radiator fan relay control circuit.
0F* P1595 Speed Control Solenoid
CircuitsAn open or shorted condition detected in the Speed
Control vacuum or vent solenoid circuits.
10* P0645 A/C Clutch Relay Circuit An open or shorted condition detected in the A/C clutch
relay circuit.
11 P0403 EGR Solenoid Circuit An open or shorted condition detected in the EGR
transducer solenoid circuit.
12 P0443 EVAP Purge Solenoid
CircuitAn open or shorted condition detected in the duty cycle
purge solenoid circuit.
13 P0203 Injector #3 Control Circuit Injector #3 output driver does not respond properly to
the control signal.
14 P0202 Injector #2 Control Circuit Injector #2 output driver does not respond properly to
the control signal.
15 P0201 Injector #1 Control Circuit Injector #1 output driver does not respond properly to
the control signal.
19 P0505 Idle Air Control Motor
CircuitsA shorted or open condition detected in one or more of
the idle air control motor circuits.
1A P0122 Throttle Position Sensor
Voltage LowThrottle position sensor input below the minimum
acceptable voltage.
1B P0123 Throttle Position Sensor
Voltage HighThrottle position sensor input above the maximum
acceptable voltage.
1E P0117 ECT Sensor Voltage Too
LowEngine coolant temperature sensor input below
minimum acceptable voltage.
1F P0118 ECT Sensor Voltage Too
HighEngine coolant temperature sensor input above
maximum acceptable voltage.
PLEMISSION CONTROL SYSTEMS 25 - 3
DESCRIPTION AND OPERATION (Continued)

system begins to pump up to this pressure. As the
pressure increases, the cycle rate starts to drop off. If
there is no leak in the system, the pump would even-
tually stop pumping at the equalized pressure. If
there is a leak, it will continue to pump at a rate rep-
resentative of the flow characteristic of the size of the
leak. From this information we can determine if the
leak is larger than the required detection limit (cur-
rently set at .020º orifice by CARB). If a leak is
revealed during the leak test portion of the test, the
test is terminated at the end of the test mode and no
further system checks will be performed.
After passing the leak detection phase of the test,
system pressure is maintained by turning on the
LDP's solenoid until the purge system is activated.
Purge activation in effect creates a leak. The cycle
rate is again interrogated and when it increases due
to the flow through the purge system, the leak check
portion of the diagnostic is complete.
The canister vent valve will unseal the system
after completion of the test sequence as the pump
diaphragm assembly moves to the full travel position.
Evaporative system functionality will be verified by
using the stricter evap purge flow monitor. At an
appropriate warm idle the LDP will be energized to
seal the canister vent. The purge flow will be clocked
up from some small value in an attempt to see a
shift in the 02 control system. If fuel vapor, indicated
by a shift in the 02 control, is present the test is
passed. If not, it is assumed that the purge system is
not functioning in some respect. The LDP is again
turned off and the test is ended.
TRIP DEFINITION
A ªTripº means vehicle operation (following an
engine-off period) of duration and driving mode such
that all components and systems are monitored at
least once by the diagnostic system. The monitors
must successfully pass before the PCM can verify
that a previously malfunctioning component is meet-
ing the normal operating conditions of that compo-
nent. For misfire or fuel system malfunction, the
MIL may be extinguished if the fault does not recur
when monitored during three subsequent sequential
driving cycles in which conditions are similar to
those under which the malfunction was first deter-
mined.
Anytime the MIL is illuminated, a DTC is stored.
The DTC can self erase only when the MIL has been
extinguished. Once the MIL is extinguished, the
PCM must pass the diagnostic test for the most
recent DTC for 40 warm-up cycles (80 warm-up
cycles for the Fuel System Monitor and the Misfire
Monitor). A warm-up cycle can best be described by
the following:
²The engine must be running²A rise of 40ÉF in engine temperature must occur
from the time when the engine was started
²Engine coolant temperature must reach at least
160ÉF
²A ªdriving cycleº that consists of engine start up
and engine shut off.
Once the above conditions occur, the PCM is con-
sidered to have passed a warm-up cycle. Due to the
conditions required to extinguish the MIL and erase
the DTC, it is most important that after a repair has
been made, all DTC's be erased and the repair veri-
fied.
COMPONENT MONITORS
There are several components that will affect vehi-
cle emissions if they malfunction. If one of these com-
ponents malfunctions the Malfunction Indicator
Lamp (Check Engine) will illuminate.
Some of the component monitors are checking for
proper operation of the part. Electrically operated
components now have input (rationality) and output
(functionality) checks. Previously, a component like
the Throttle Position sensor (TPS) was checked by
the PCM for an open or shorted circuit. If one of
these conditions occurred, a DTC was set. Now there
is a check to ensure that the component is working.
This is done by watching for a TPS indication of a
greater or lesser throttle opening than MAP and
engine rpm indicate. In the case of the TPS, if engine
vacuum is high and engine rpm is 1600 or greater
and the TPS indicates a large throttle opening, a
DTC will be set. The same applies to low vacuum
and 1600 rpm.
Any component that has an associated limp in will
set a fault after 1 trip with the malfunction present.
Refer to the Diagnostic Trouble Codes Description
Charts in this section and the appropriate Power-
train Diagnostic Procedure Manual for diagnostic
procedures.
NON-MONITORED CIRCUITS
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.
PLEMISSION CONTROL SYSTEMS 25 - 9
DESCRIPTION AND OPERATION (Continued)