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Chapter 6 Emissions control systems
Motor position sensor
connector
16.40 To check the motor position sensor (2.4 models only),
measure the resistance between terminal 2 and terminal 3 of the
electrical connector
16.48 To check the oxygen sensor on 3.OL models, check the
continuity between terminal 2 and terminal 4 of the connector
35 Unplug the electrical connector from the throttle posrtron sensor.
36 Check the continuity between terminal 1 (sensor ground) and termi-
nal 2 (idle position switch) of the throttle position sensor connector (see
illustration). With the accelerator pedal pushed down, there shouldn’t be
any continuity (infinite resistance); with the pedal released, there should
be continuity (zero resistance). If there is no continuity when the accelera-
tor pedal is returned, loosen the throttle position sensor mounting screws,
turn the sensor as far as it will go in the clockwise direction and check
again If the throttle position sensor still fails either test, replace it (the idle
position switch is inside the throttle position sensor, so you have to replace
the throttle position sensor to replace the idle position switch).
37 If you install a new throttle position sensor/idle position switch unit,
adjust it [see Steps 18 through 30) before tightening the throttle position
sensor mounting screws securely.
38 Plug in the electrical connector.
Motor position sensor (2.4L engine only)
Refer to illustration 16.40
39 Unplug the electrical connector from the motor position sensor.
40 Measure the resistance between terminals 2 and 3 (see illustration).
Compare your measurement with the value listed in this Chapter’s Specifi-
cations. If the indicated value isn’t within this range, replace the motor po-
sition sensor.
41 Unplug the electrical connector from the idle-speed control servo.
42 Hook up a6V DC battery between terminals 1 and 2 of the idle-speed
control servo connector (see illustration), then measure the resistance
between terminals 3 and 5 of the motor position sensor connector while
the idle-speed control servo is powered up by the 6V battery (it should ex-
pandand contract). If the motor position sensor is functioning properly, the
indicated-resistance should decrease smoothly as the idle speed control
servo plunger contracts.
43 If the indicated resistance doesn’t behave this way, or if the change
isn’t smooth, replace the idle speed control servo assembly.
Oxygen sensor
2.4L engine
44 Warm up the engine to its normal operating temperature.
45 Unplug the electrical connector to the oxygen sensor and hook up a
digital voltmeter between the connector terminal and ground (1990 mod-
em orbetwee?i the connector terminals (1991 models).
46 Race the engine several times and note the oxygen sensor output
voltage. Compare your measurement to the output voltage values listed in
this Chapter’s Specifications. If the indicated output voltage falls outside
the specified value, replace the oxygen sensor (see Chapter 1).
16.51 Connect terminal 2 and terminal 4 of the connector to the
posltive and negative battery terminals, respectively, with jumper
wires, hook up a digital voltmeter to terminal 1 and terminal 3 of
the connector, race the engine several times and measure the
output voltage of the oxygen sensor
3.OL engine
Refer to illustrations 16.48 and 16.51
.
47 Unplug the electrical connector for the oxygenTsensor.
48 Check the continuity between terminal 2 and terminal 4 of the connec
tor (see illustration). There should be about 20 ohms of resistance when
the sensor is cool (approximately g°rees F).
49 If there’s no continuity, replace the oxygen sensor (see Chapter 1).
50 Warm up the engine to normal operating temperature.
51 Connect terminal 2 and terminal 4 of the connector to the positive and
negative battery terminals, respectively, with jumper wires (see illustra-
tion). Caution: Connecting the terminals on the connector to the battery
terminals in the reverse order can damage the oxygen sensor.
52 Hook up adigitaf voltmeter to termrnal 1 and terminal 3 of the connec-
tor.
53 Race the engine several times and measure the output voltage of the
oxygen sensor. Compare your measurement with the output voltage listed
in this Chapter’s Specifications. If the indicated voltage isn’t within the
specified voltage range, replace the oxygen sensor (see Chapter 1).
EGR temperature sensor (California models only)
54 See Section 7 for this procedure.
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