Locate the diagnostic connector in or under the glove compartment. (Summit models in fuse box)Connect analog voltmeter to upper LH (+) and lower RH (-) terminalsMost Summit models, connect voltmeter (+) to upper LH of the 12 pin connector and (-) to the 2 middleSOME Station wagon models you may have to ground the upper LH of the 16 pin connectorTurn the ignition on, then watch the sweeps of the vlotmeterLong sweeps are tens and shirt sweeps are ones.Continuous short sweeps indicated no codes.
Disconnect the battery from the Negative terminal to clear codes.
See Figures 1 and 2
The intake air temperature sensor (provided on the air flow sensor on all engines, except the 1995-98 2.0L non-turbo) is a resistor which measures the intake air temperature. The ECU will determine the intake air temperature according to the output voltage from the sensor, and compensates the fuel injection amount according to the intake air temperature.
Fig. 1: Location of the intake air temperature sensor (integral with the volume air flow sensor)-1990-94 vehicles
Fig. 2: On 1995-98 2.0L non-turbo engines, the IAT sensor is mounted on the intake plenum
When the intake air temperature sensor is faulty, it controls the fuel injection amount based on an intake air temperature default of 77°F (25°C). The driveability of the vehicle may become poor during cold temperature operation. The trouble may not be noticeable when the ambient temperature is around 77°F (25°C).
Except 1995-98 2.0L Non-Turbo Engine
See Figures 3, 4 and 5
Detach the air flow sensor electrical connector.
Fig. 3: IAT sensor terminal identification-1990-94 vehicles
Fig. 4: IAT sensor terminal identification-1995-98 2.0L turbo and 2.4L engines
Fig. 5: Measure the intake air temperature sensor resistance while heating it with a hair drier
If equipped with non-turbo engines, measure the resistance between terminals No. 4 and No. 6 of the electrical connector.
If equipped with turbo engine, measure the resistance between terminals No. 6 and No. 8 of the sensor electric connector.
Compare test readings to specifications:
Sensor temperature of 32°F (0°C)-5.3-6.7 kilo-ohms
Sensor temperature of 68°F (20°C)-2.3-3.0 kilo-ohms
Sensor temperature of 176°F (80°C)-0.30-0.42 kilo-ohms
Measure the sensor resistance while heating the sensor area with a hair dryer. As the temperature of the sensor increases, sensor resistance should become smaller.
If the measured resistance deviates from the standard value or the resistance remains unchanged, replace the air flow sensor assembly.
1995-98 2.0L Non-Turbo Engine
See Figure 6
Detach the IAT sensor connector.
If necessary, you can remove the sensor to test it.
Use a DVOM to measure the resistance between the sensor terminals and compare with the following specifications:
At 77°F (25°C), the resistance should be 9-11 kilo-ohms.
At 212°F (100°C), the resistance should be 0.6-0.8 ohms.
Fig. 6: Use an ohmmeter (1) to measure the resistance of the IAT sensor (2). Note that this sensor is within specifications
If the resistance is not within the specified range, replace the sensor.
If removed, install the sensor. Attach the connector.
REMOVAL & INSTALLATION
Except 1995-98 2.0L Non-Turbo Engines
See Figure 1
Disconnect the negative battery cable.
Unplug the sensor electrical connector from the sensor.
If necessary, carefully remove the lid of the air filter housing.
Unfasten the retainers, then remove the sensor from the air cleaner housing.
Installation is the reverse of the removal procedure.
1995-98 2.0L Non-Turbo Engines
See Figures 7, 8 and 9
Detach the IAT sensor harness connector.
Fig. 7: Unplug the IAT sensor electrical connector
Unthread the IAT sensor and remove from the intake plenum.
Fig. 8: Use a open-end wrench to loosen ...
Fig. 9: ...then remove the IAT sensor from the vehicle
Apply Loctite® 24200 or equivalent sealant to the threads of the sensor and install in the intake plenum. Tighten the sensor to 5 ft. lbs. (7 Nm.
Attach the sensor electrical connector. Make sure it is connected securely.
Connect the negative battery cable.
1990-94 2.0L non-turbo engine-on the firewall, slightly right of center.
1990-94 2.0L turbo engine-the innermost solenoid in the solenoid cluster at the left rear corner of the engine compartment.
1990-94 NON-TURBO ENGINES
Disconnect the red striped vacuum hose from the throttle body and connect it to a hand held vacuum pump.
Plug the open nipple on the throttle body.
Using the hand pump, apply vacuum while the engine is idling. Check that vacuum is maintained or released as outlined below:
With the engine coolant at 140°F (60°C) or less-14.8 in. Hg of vacuum is maintained.
With the coolant at 158°F (70°C) or higher-14.8 in. Hg of vacuum is maintained.
With the engine coolant at 158°F (70°C) or higher, run the engine at 3000 rpm within 3 minutes of starting vehicle. Try to apply vacuum using the hand held pump. Vacuum should leak.
With the engine coolant at 158°F (70°C) or higher, run the engine at 3000 rpm after 3 minutes have elapsed after starting vehicle. Apply 14.8 in. Hg of vacuum. The vacuum should be maintained momentarily, after which it should leak.
The vacuum will leak continuously if the altitude is 7,200 ft. or higher, or the intake air temperature is 122°F (50°C) or higher.
If the test results differ from the desired results, the purge control system is not operating properly.
1990-92 TURBO ENGINES
Disconnect the purge air hose from the intake hose and plug the air intake hose.
Connect a hand vacuum pump to the purge air hose.
Under various engine conditions, inspect the system operation:
Allow the engine to cool to a temperature of 140°F (60°C) or below.
Start the engine and run at idle.
Using the hand pump, apply 14.8 in. Hg of vacuum. In this condition, the vacuum should be maintained.
Raise the engine speed to 3000 rpm.
Run the engine until the coolant temperature reaches 158°F (70°C). Inspect system operations as follows:
Using the hand pump, apply 14.8 in. Hg of vacuum with the engine at idle. In this condition, vacuum should be maintained.
Increase the engine speed to 3000 rpm within 3 minutes of starting the engine. Try applying vacuum. The vacuum should leak.
After 3 minutes have elapsed after starting engine, raise the engine speed to 3000 rpm. Apply 14.8 in. Hg of vacuum. Vacuum should be maintained momentarily, after which it will leak.
The vacuum will leak continuously if the altitude is 7200 ft. or higher or the air temperature is 122°F (50°C) or higher.
If the results of either test differs from specifications, the system is not functioning properly and will require further diagnosis.