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Home >> Mercury >> 2005 >> Montego Base, AWD >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Pinpoint Test DK: Accelerator Pedal Position Sensor Through Pinpoint Test DX: Engine Coolant Temperature (ECT) Sensor - (Except Diesel & Hybrid) >> Pinpoint Test DU: Intake Air Temperature 2 (IAT2) Sensor >> Test Procedure

Test Procedure

  1. DU1 DTC P1115: SIMULATE AN OPPOSITE SIGNAL TO THE PCM 
    • The DTC indicates the sensor signal is greater than the self-test maximum.
    • Possible causes:
      • Open in the harness.
      • Incorrect harness connections.
      • Damaged sensor.
      • Damaged PCM.
    • IAT2 connector disconnected.
    • Key in ON position.
    • Connect a 5 amp fused jumper wire between the following:
      Point A IAT2 Connector, Harness Side Point B IAT2 Connector, Harness Side
      IAT2 - Pin 1 SIGRTN - Pin 2

    Does a diagnostic tool communication concern exist? 

    Yes No
    Key in OFF position.
    REMOVE the jumper.
    GO to  DU4.    		 GO to  DU2.
  2. DU2 CHECK FOR OPPOSITE SIGNAL TO PCM 
    • Jumper installed.
    • Access the PCM and monitor the IAT2 V PID.

    Is the voltage less than 0.2 V? 

    Yes No
    INSTALL a new IAT2 sensor. Key in OFF position.
    REMOVE the jumper.
    GO to  DU3.
  3. DU3 CHECK THE SIGNAL AND SIGRTN CIRCUITS FOR AN OPEN IN THE HARNESS 
    • PCM connector disconnected.
    • Measure the resistance between:
      (+) IAT2 Connector, Harness Side (-) PCM Connector, Harness Side
      IAT2 - Pin 1 IAT2 - Pin 37
      SIGRTN - Pin 2 SIGRTN - Pin 91

    Are the resistances less than 5 ohms? 

    Yes No
    INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) . REPAIR the open circuit.
  4. DU4 CHECK THE SENSOR SIGNAL FOR A SHORT TO VREF 
    • Key in OFF position.
    • PCM connector disconnected.
    • Measure the resistance between:
      (+) PCM Connector, Harness Side (-) PCM Connector, Harness Side
      IAT2 - Pin 37 VREF - Pin 90

    Is the resistance greater than 10K ohms? 

    Yes No
    INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) . REPAIR the short circuit to VREF.
  5. DU5 DTC P1114: SIMULATE AN OPPOSITE SIGNAL TO THE PCM 
    • The DTC indicates the sensor signal is less than the self-test minimum.
    • Possible causes:
      • Grounded circuit in the harness.
      • Incorrect harness connections.
      • Damaged sensor.
      • Damaged PCM.
    • IAT2 connector disconnected.
    • Key in ON position.
    • Access the PCM and monitor the IAT2 V PID.

    Is the voltage greater than 4.2 V? 

    Yes No
    Key in OFF position. INSTALL a new IAT2 sensor. Key in OFF position.
    GO to  DU6.
  6. DU6 CHECK THE SENSOR SIGNAL FOR A SHORT TO GROUND 
    • PCM connector disconnected.
    • Measure the resistance between:
      (+) PCM Connector, Harness Side (-) PCM Connector, Harness Side
      IAT2 - Pin 37 SIGRTN - Pin 91
    • Measure the resistance between:
      (+) PCM Connector, Harness Side (-) 12 Volt Vehicle Battery
      IAT2 - Pin 37 Negative terminal

    Is the resistance greater than 10K ohms? 

    Yes No
    INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) . REPAIR the short circuit.
  7. DU7 DTC P0127: IAT2 TOO HIGH. CHECK CHARGE AIR COOLER PUMP OPERATION 

    Does the supercharger intercooler pump run? 

    Yes No
    GO to  DU8. Key in OFF position.
    Diagnose charge air cooler (CAC) pump.
    GO to PINPOINT TEST KP STEP 8 .
  8. DU8 CHECK THE INTERCOOLER SYSTEM 
    • Check intercooler system for low fluid level, cracked, blocked or misrouted coolant lines, cracked or blocked heat exchanger.

    Is a concern present? 

    Yes No
    Key in OFF position.
    REPAIR as necessary.    		 GO to  DU9.
  9. DU9 SIMULATE THE HIGH IAT2 SIGNAL TO THE PCM 
    • Key in ON position.
    • Access the PCM and monitor the IAT2 V PID.
    • Observe the PID while disconnecting the IAT2 sensor.

    Is the voltage greater than 4.2 V? 

    Yes No
    Key in OFF position.
    GO to  DU10.    		 INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) .
  10. DU10 SIMULATE THE LOW IAT2 SIGNAL TO THE PCM 
    • IAT2 connector disconnected.
    • Connect a 5 amp fused jumper wire between the following:
      Point A IAT2 Connector, Harness Side Point B IAT2 Connector, Harness Side
      IAT2 - Pin 1 SIGRTN - Pin 2
    • Key in ON position.
    • Access the PCM and monitor the IAT2 V PID.

    Is the voltage less than 0.2 V? 

    Yes No
    CONNECT the sensor and GO to REFERENCE VALUES - GASOLINE MODELS .
    COMPARE the IAT2 PID to reference values under different road test conditions.
    If sensor is not in range INSTALL a new sensor.    		 INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) .
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