(13) Check the vacuum connections at the throttle
body and intake plenum (Fig. 81).
(14) Ensure the idle air control motor and TPS
electrical connectors are fully seated and not dam-
aged (Fig. 82).
(15) Inspect the park/neutral switch wiring connec-
tion for damage. Ensure the automatic transaxle
electrical connections are not damaged (Fig. 83).(16) Inspect the PCV system connections for dam-
age (Fig. 84).
(17) Inspect the crankshaft position sensor electri-
cal connector for damage (Fig. 85).
(18) Verify the Manifold Absolute Pressure (MAP)
sensor electrical connector is attached to the sensor
and not damaged (Fig. 86).
Fig. 81 Throttle Body Vacuum Connections
Fig. 82 Throttle Body Electrical Connections
Fig. 83 Automatic Transaxle Electrical Connections
Fig. 84 PCV Valve and Fresh Air Hose
NSFUEL SYSTEM 14 - 57
DIAGNOSIS AND TESTING (Continued)
(19) Check the heated oxygen sensor electrical con-
nectors for damage (Fig. 87) and (Fig. 88).(20) Verify the engine ground strap is attached at
the engine and dash panel. Inspect the strap for cor-
rosion or damage.
(21) Inspect the generator wiring connections for
damage.
(22) Check the accessory drive belt tension.
(23) Check the 40-way electrical connectors at the
Powertrain Control Module (PCM) (Fig. 89) for dam-
age or spread terminals. Verify that the connectors
are fully inserted into the PCM sockets. Ensure the
wires are not stretched or pulled out of the connector.
(24) Inspect fuses in the Power Distribution Cen-
ter (PDC). Verify all fuses and relays are fully
Fig. 85 Crankshaft Position Sensor
Fig. 86 MAP Sensor
Fig. 87 Upstream Heated Oxygen Sensor
Fig. 88 Downstream Heated Oxygen Sensor
Fig. 89 Powertrain Control Module (PCM)
Connectors
14 - 58 FUEL SYSTEMNS
DIAGNOSIS AND TESTING (Continued)
²The PCM grounds the coil side of the relay
through terminal number 85.
²Terminal number 86 supplies voltage to the coil
side of the relay.
²When the PCM de-energizes the ASD and fuel
pump relays, terminal number 87A connects to termi-
nal 30. This is the Off position. In the off position,
voltage is not supplied to the rest of the circuit. Ter-
minal 87A is the center terminal on the relay.
²When the PCM energizes the ASD and fuel
pump relays, terminal 87 connects to terminal 30.
This is the On position. Terminal 87 supplies voltage
to the rest of the circuit.
TESTING
The following procedure applies to the ASD and
fuel pump relays.
(1) Remove relay from connector before testing.
(2) With the relay removed from the vehicle, use
an ohmmeter to check the resistance between termi-
nals 85 and 86. The resistance should be between 75
65 ohms.
(3) Connect the ohmmeter between terminals 30
and 87A. The ohmmeter should show continuity
between terminals 30 and 87A.
(4) Connect the ohmmeter between terminals 87
and 30. The ohmmeter should not show continuity at
this time.
(5) Connect one end of a jumper wire (16 gauge or
smaller) to relay terminal 85. Connect the other end
of the jumper wire to the ground side of a 12 volt
power source.
(6) Connect one end of another jumper wire (16
gauge or smaller) to the power side of the 12 volt
power source.Do not attach the other end of the
jumper wire to the relay at this time.
WARNING: DO NOT ALLOW OHMMETER TO CON-
TACT TERMINALS 85 OR 86 DURING THIS TEST.(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.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
To perform a complete test of the MAP sensor and
its circuitry, refer to the DRB scan tool and appropri-
ate Powertrain Diagnostics Procedures manual. To
test the MAP sensor only, refer to the following:
CAUTION: When testing the MAP sensor, be sure
that the harness wires are not damaged by the test
meter probes.
(1) Test the MAP sensor output voltage at the
MAP sensor connector between terminals 2 and 3
(Fig. 95). With the ignition switch ON and the engine
not running, output voltage should be 4 to 5 volts.
The voltage should drop to 1.5 to 2.1 volts with a hot,
neutral idle speed condition. If OK, go to next step. If
not OK, go to step 3.
(2) Test PCM terminal 36 for the same voltage
described in the previous step to verify wire harness
condition. Repair as required.
(3) Test the MAP sensor ground circuit at sensor
connector terminal 1 and PCM terminal 43. If OK, go
to next step. If not OK, repair as required.
(4) Test MAP sensor supply voltage between sen-
sor connector terminals 2 and 1 with the key ON.
The voltage should be approximately 5 volts (6.5V).
Five volts (6.5V) should also be at terminal 61 of the
Fig. 94 ASD and Fuel Pump Relay Terminals
Fig. 95 MAP Sensor Connector
14 - 60 FUEL SYSTEMNS
DIAGNOSIS AND TESTING (Continued)
PCM. If OK, replace MAP sensor. If not OK, repair or
replace the wire harness as required.
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.
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 gener-
ates 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 at about 20mVac (at about 700 rpm) and
increases to approximately 600 mVac (5000 rpm). If
the output falls outside of this range a DTC will be
set.
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. 96) or
(Fig. 97) or (Fig. 98).
(2) Connect a high input impedance (digital) volt-
ohmmeter to terminals A and B (Fig. 99). The ohm-
meter should read as follows:
(a) ECT STET at normal operating temperature
around 200ÉF should read approximately 700 to
1,000 ohms.
(b) ECT STET at room temperature around 70ÉF
ohmmeter should read approximately 7,000 to
13,000 ohms.
(3) Test the resistance of the wire harness between
the PCM connector terminal 26 and the sensor har-
ness connector. Also check for continuity between
PCM connector terminal 43 and the sensor harness
connector. Refer to Group 8W, Wiring diagrams for
Fig. 96 Engine Coolant Temperature SensorÐ2.4L
Fig. 97 Engine Coolant Temperature SensorÐ3.0L
Fig. 98 Engine Coolant Temperature SensorÐ3.3/
3.8L
NSFUEL SYSTEM 14 - 61
DIAGNOSIS AND TESTING (Continued)
circuit information. If the resistance is greater than 1
ohm, repair the wire harness as necessary.
THROTTLE POSITION SENSOR
To perform a complete test of the this sensor and
its circuitry, refer to the DRB scan tool and appropri-
ate Powertrain Diagnostics Procedures manual. To
test the throttle position sensor only, refer to the fol-
lowing:
The Throttle Position Sensor (TPS) can be tested
with a digital voltmeter (DVM). The center terminal
of the sensor is the output terminal. One of the other
terminals is a 5 volt supply and the remaining ter-
minal is ground.
Connect the DVM between the center and sensor
ground terminal. Refer to Group 8W - Wiring Dia-
grams for correct pinout.
With the ignition switch in the ON position, check
the output voltage at the center terminal wire of the
connector. Check the output voltage at idle and at
Wide-Open-Throttle (WOT). At idle, TPS output volt-
age should be approximately 0.38 volts to 1.2 volts.
At wide open throttle, TPS output voltage should be
approximately 3.1 volts to 4.4 volts. The output volt-
age should gradually increase as the throttle plate
moves slowly from idle to WOT.
Check for spread terminals at the sensor and PCM
connections before replacing the TPS.
THROTTLE BODY MINIMUM AIR FLOW CHECK
PROCEDURE
(1) Warm engine in Park or Neutral until the cool-
ing fan has cycled on and off at least once.
(2) Ensure that all accessories are off.
(3) Shut off engine.
(4)3.0L Engine
(a) Hook-up the timing check device and tachom-
eter.(b) Disconnect the engine coolant temperature
sensor and set basic timing to 12É BTDC62É.
(c) Shut off engine. Reconnect coolant tempera-
ture sensor wire.
(5) Disconnect the PCV valve hose from the intake
manifold nipple (Fig. 101), (Fig. 102) or (Fig. 103).
(6) Cap the PCV valve nipple.
(7)3.3/3.8L Engines
(a) Install Air Metering Fitting 6457 (0.125 in.
orifice) to the intake manifold PCV nipple (Fig.
100).
(b) Disconnect the idle purge line from the throt-
tle body nipple.
(8)3.0/2.4L Engines
(a) Install Air Metering Fitting 6457 (0.125 in.
orifice) to the purge nipple on the throttle body.
(9)3.3/3.8L Engines
(a) Cap the 3/16 inch nipple.
(b) Connect the DRB scan tool to the data link
connector.
(10) Restart the engine. Allow engine to idle until
the cooling fan has cycled on and off at least one
180ÉF cycle.
(11) Using the DRB scan tool, access the Minimum
Airflow Idle Speed screen.
(12) The following will then occur:
²Idle air control motor will fully close.
²Idle spark advance will become fixed.
²DRB scan tool displays engine rpm.
(13) If idle rpm is within the range shown in the
Idle Specification chart, throttle body minimum air-
flow is set correctly.
IDLE SPECIFICATIONSÐ2.4L ENGINE
Odometer Reading Idle RPM
Below 1000 Miles.................500-875 RPM
Above 1000 Miles.................550±875 RPM
Fig. 99 Engine Coolant Temperature Sensor
Fig. 100 Air Metering Fitting 6457
14 - 62 FUEL SYSTEMNS
DIAGNOSIS AND TESTING (Continued)
REMOVAL AND INSTALLATION
THROTTLE BODY
REMOVAL
(1) Disconnect negative cable from battery cable.
(2) Remove air inlet to throttle body hose clamp.
(3) Remove 2 screws and air inlet resonator (Fig.
104).
(4) Remove throttle and the speed control (if
equipped) cables from lever and bracket (Fig. 105).
(5) Disconnect electrical connectors from the idle
air control motor and throttle position sensor (TPS)
(Fig. 106) or (Fig. 107) or (Fig. 108).(6) Disconnect vacuum hoses from throttle body.
(7) Remove throttle body to intake manifold
attaching nuts.
(8) Remove throttle body and gasket.
INSTALLATION
(1) Reverse procedure for installation. Tighten
throttle body mounting nuts to 25 N´m (225 in. lbs.)
torque.
FUEL PUMP RELAY
The fuel pump relay is located in the PDC. The
inside top of the PDC cover has a label showing relay
and fuse location.
AUTOMATIC SHUTDOWN (ASD) RELAY
The Automatic Shutdown relay (ASD) relay is
located in the PCD. The inside top of the PDC cover
has a label showing relay and fuse location.
Fig. 104 Air Inlet Resonator
Fig. 105 Throttle Cable Attachment to Throttle Body
Attachment
Fig. 106 Throttle Body Electrical and Vacuum
ConnectionsÐ2.4L
Fig. 107 Throttle Body Electrical and Vacuum
ConnectionsÐ3.0L
14 - 64 FUEL SYSTEMNS
THROTTLE POSITION SENSOR
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove electrical connector from throttle posi-
tion sensor.
(3) Remove throttle position sensor mounting
screws.
(4) Lift throttle position sensor off throttle shaft
(Fig. 109), (Fig. 110) or (Fig. 111).
INSTALLATION
(1) Install throttle position sensor on throttle
shaft. Install mounting screws. Tighten screw to 2
N´m (17 in. lbs.) torque.(2) Connect electrical connector to throttle position
sensor.
(3) Connect negative cable to battery.
IDLE AIR CONTROL MOTOR
When servicing throttle body components, always
reassemble components with new O-rings and seals
where applicable. Never use lubricants on O-rings or
seals, damage may result. If assembly of component
is difficult, use water to aid assembly. Use care when
removing hoses to prevent damage to hose or hose
nipple.
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove electrical connector from idle air con-
trol motor.
(3) Remove idle air control motor mounting screws
(Fig. 112).
(4) Remove motor from throttle body. Ensure the
O-ring is removed with the motor.
Fig. 108 Throttle Body Electrical and Vacuum
ConnectionsÐ3.3/3.8L
Fig. 109 Servicing Throttle Position SensorÐ2.4L
Fig. 110 Servicing Throttle Position SensorÐ3.0L
Fig. 111 Servicing Throttle Position SensorÐ3.3/3.8L
NSFUEL SYSTEM 14 - 65
REMOVAL AND INSTALLATION (Continued)
INSTALLATION
(1) The new idle air control motor has a new
O-ring installed on it. If pintle measures more than 1
inch (25 mm) it must be retracted. Use the DRB Idle
Air Control Motor Open/Close Test to retract the
pintle (battery must be connected.)
(2) Carefully place idle air control motor into
throttle body.
(3) Install mounting screws. Tighten screws to 2
N´m (17 in. lbs.) torque.
(4) Connect electrical connector to idle air control
motor.
(5) Connect negative cable to battery.
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSORÐ2.4/3.3/3.8L
REMOVAL
(1) Disconnect electrical connector from MAP sen-
sor (Fig. 113).
(2) Remove two screws holding sensor to the
intake manifold.
INSTALLATION
(1) Reverse the above procedure for installation.
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSORÐ3.0L
REMOVAL
(1) Remove vacuum hose and mounting screws
from manifold absolute pressure (MAP) sensor (Fig.
114).
(2) Disconnect electrical connector from sensor.
Remove sensor.
INSTALLATION
(1) Reverse the above procedure for installation.
PROPORTIONAL PURGE SOLENOID VALVE
REMOVAL
(1) Remove vacuum hose and electrical connector
from solenoid (Fig. 115).
(2) Pull solenoid up to remove it from mounting
bracket.
INSTALLATION
Reverse above procedure for installation.
Fig. 112 Servicing Idle Air Control MotorFig. 113 Map Absolute Pressure Sensor
Fig. 114 Manifold Absolute Pressure Sensor
14 - 66 FUEL SYSTEMNS
REMOVAL AND INSTALLATION (Continued)