Protege 1999-2000

Intake Air Temperature Sensor

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Operation



Specific to:

Mazda Protege 1999-2003

The intake air temperature sensor is a variable resistor that is influenced by temperature. Which means, as the temperature changes, so does the resistance inside the sensor. The computer reads this change in resistance to determine the temperature of the incoming air. It uses this reading to determine proper air/fuel mixture and ignition timing settings.

Removal & Installation



Specific to:

Mazda Protege 1999-2003

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the IAT sensor from the air cleaner housing or intake air pipe.
  4.  

To install:

  1. Install a new sealing washer to the thermosensor.
  2.  

Testing



1.6L Engine
Circuit Open/Short Inspection

Specific to:

Mazda Protege 1998-2001

  1. Disconnect the PCM connector at the vehicle harness connector.
  2.  
  3. Connect the 104-Pin Breakout Box to the PCM with the vehicle harness connector.
  4.  
  5. Tighten the connector attaching screw.
  6.  
  7. Inspect for an open or short circuit in the following wiring harnesses by probing the applicable sensor and 104-Pin Breakout Box) terminals with ohmmeter leads.
    1. If there is an open or short circuit, repair or replace wiring harnesses.
    2.  
    3. If there is no open or short circuit, replace the MAF sensor.

      Click image to see an enlarged view

      Fig. Showing the IAT/MAF connector pin arrangements for testing

    4.  

  8.  
  9. To check for open circuit:

    MAF signal circuit (MAF sensor connector terminal C and PCM connector terminal 88)
     
    Power circuit (MAF sensor connector terminal A and main relay terminal D through common connector)
     
    GND circuit (MAF sensor connector terminal B and PCM connector terminal 77 through common connector)
     

  10.  
  11. To check for short circuit:

    MAF signal circuit (MAF sensor connector terminal C and PCM connector terminal 88 to GND)
     
    Power circuit (MAF sensor connector terminal A and main relay terminal D through common connector to GND)
     

  12.  
  13. Reconnect the MAF sensor connector.
    NOTE
    The scan tool shows the MAF rate and load value.



    Click image to see an enlarged view

    Fig. Scan tool reference signal chart. 1. 650-750 RPM; 2. No load, neutral or P position

  14.  

IAT Sensor Resistance Inspection

Specific to:

Mazda Protege 1998-2001

  1. Disconnect the MAF sensor connector.
  2.  
  3. Measure the resistance between MAF sensor terminals D and E using an ohmmeter.
    1. If not as specified, replace the MAF sensor.
    2.  
    3. If IAT sensor is okay, but PID value or PCM terminal 39 voltage are out of specification, carry out the -Circuit Open/Short Inspection-.
    4.  
    5. Resistance specifications should be:

      At 50°F (10°C): 3.1-4.4 k-ohms
       
      At 68°F (20°C): 2.2-2.7 k-ohms
       
      At 86°F (20°C): 1.4-1.9 k-ohms
       

    6.  

  4.  

MAF Sensor Inspection

Specific to:

Mazda Protege 1998-2001

  1. Visually inspect for damage, cracks, terminal bends and terminal rust on the MAF sensor.
  2.  
  3. If any of the above are found, replace the MAF sensor.
  4.  
  5. If the MAF sensor PID value or PCM terminal 88 voltage are out of specification, carry out the -Circuit Open/Short Inspection-.
  6.  

 
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