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14 - 40
FUEL SYSTEM
DIAGNOSIS AND TESTING (Continued)
priate Powertrain Diagnostics Procedures manual. To
test the O2S sensors only, refer to the following:
The upstream O2S sensor is located on the exhaust
downpipe (Fig. 31).
The downstream O2S sensor is located near the
outlet end of the catalytic converter (Fig. 32).
Fig. 31 Upstream Oxygen Sensor Location
Fig. 32 Downstream Oxygen Sensor Location
Each O2S heating element can be tested with an
ohmmeter as follows:
Disconnect the O2S sensor connector. Connect the
ohmmeter test leads across the white wire terminals
of the sensor connector. Resistance should be
between 4.5
.5 ohms and 7 ohms. Replace the sen-
sor if the ohmmeter displays an infinity (open) read-
ing.
ENGINE COOLANT TEMPERATURE SENSOR
To perform a complete test of the engine coolant
temperature sensor and its circuitry, refer to DRB
scan tool and appropriate Powertrain Diagnostics
Procedures manual. To test the sensor only, refer to
the following:
(1) Disconnect wire harness connector from coolant
temperature sensor (Fig. 33).
Fig. 33 Engine Coolant Temperature Sensor—
(2) Test the resistance of sensor with a high input
impedance (digital) volt-ohmmeter. Refer to SENSOR
RESISTANCE
(OHMS)—COOLANT
TURE
SENSOR/INTAKE
SENSOR chart. The resistance (as measured across
sensor terminals) should be within range shown in
chart. If not, replace sensor.
(3) Test continuity of the wire harness between the
PCM wire harness connector and the coolant sensor
connector terminals. Refer to Group 8, Wiring for ter-
minal/cavity locations. Repair the wire harness if an
open circuit is indicated.
IDLE AIR CONTROL (IAC) MOTOR
To perform a complete test of the IAC motor and
its circuitry, refer to DRB scan tool and appropriate
Powertrain Diagnostics Procedures manual.
INTAKE MANIFOLD AIR TEMPERATURE
SENSOR
To perform a complete test of the intake manifold
air temperature sensor and its circuitry, refer to DRB
tester and appropriate Powertrain Diagnostics Proce-
dures manual. To test the sensor only, refer to the
following:
Typical
TEMPERA-
AIR
TEMPERATURE
TJ
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