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Test Procedure

  1. FB1 PRELIMINARY DIAGNOSIS 
    NOTE: Diagnose any circuit DTCs before range or performance DTCs.

    Is DTC P0071, P0072, P0073 or P0074 present? 

    Yes No
    GO to  FB2. RETURN to SYMPTOM CHARTS for further direction.
  2. FB2 CHECK FOR AN OPEN 
    • Ignition OFF.
    • PCM connector disconnected.
    • AAT Sensor connector disconnected.
    • Measure the resistance between:
      (+) AAT Sensor Connector, Harness Side (-) PCM Connector, Harness Side
      AAT - Pin 1 AAT - Pin B33
      SIGRTN - Pin 2 SIGRTN - Pin B45

    Are the resistances less than 5 ohms? 

    Yes No
    GO to  FB3. REPAIR the open circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  3. FB3 CHECK FOR A SHORT 
    • Measure the resistance between:
      (+) AAT Sensor Connector, Harness Side (-)
      AAT - Pin 1 Ground
    • Measure the resistance between:
      (+) AAT Sensor Connector, Harness Side (-) AAT Sensor Connector, Harness Side
      AAT - Pin 1 SIGRTN - Pin 2

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  FB4. REPAIR the short circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  4. FB4 CHECK FOR A SHORT TO VOLTAGE 
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) AAT Sensor Connector, Harness Side (-)
      AAT - Pin 1 Ground

    Is any voltage present? 

    Yes No
    REPAIR the short circuit. Clear the PCM DTCs.
    REPEAT the self-test.    		 GO to  FB5.
  5. FB5 INTERMITTENT CHECK 
    • Ignition OFF.
    • PCM connector connected.
    • AAT Sensor connector connected.
    • Ignition ON, engine OFF.
    • Access the PCM and monitor the AAT_V (VOLT) PID.
    • While observing the PID, wiggle, shake, and bend small sections of the wiring harness working from the sensor to the PCM.
    • Lightly tap on the AAT sensor and wiggle the harness connector to simulate road shock.

    Is a concern present? 

    Yes No
    REPAIR as necessary.
    Clear the PCM DTCs. REPEAT the self-test.    		 GO to  FB6.
  6. FB6 CHECK THE RESISTANCE OF THE AAT SENSOR 
    NOTE: Verify the external temperature of the sensor is at ambient temperature. Refer to the chart at the beginning of this test for the temperature and resistance values.
    • Ignition OFF.
    • AAT Sensor connector disconnected.
    • Measure the resistance between:
      (+) AAT Sensor Connector, Component Side (-) AAT Sensor Connector, Component Side
      AAT - Pin 1 SIGRTN - Pin 2

    Is the resistance within specification? 

    Yes No
    The system is operating correctly at this time.
    The concern may have been caused by a loose or corroded connector.    		 INSTALL a new AAT sensor. REFER to the Climate Control System article.
    Clear the PCM DTCs. REPEAT the self-test.
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