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Home >> Mercury >> 2007 >> Montego Base, FWD >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Pinpoint Test JE: Integrated Ignition Coil Pack A, B, Or C Failure Through Pinpoint Test Kn: Variable Speed Electric Cooling Fan - (Except Diesel & Hybrid) >> PINPOINT TEST KE: Idle Air Control (IAC) Valve >> Test Procedure

Test Procedure

  1. KE1 CHECK FOR DIAGNOSTIC TROUBLE CODES (DTCS) 
    • Are DTCs P0505, P0506, P0507, P0511, P1504, P1506, or P1507 present? 
    Yes @
    No
    For DTCs P0505, P0506, P0511, P1504 or P1507, GO to  KE2.
    For DTCs P0507 or P1506, GO to  KE15.    		 For all other symptoms without DTCs, GO to  KE2.
  2. KE2 DTCS P0505, P0506, P0511, P1504 OR P1507: CHECK FOR INLET AIR LEAKS (OR STARTS ONLY AT PART THROTTLE) 
    • With the engine running at idle (if possible), listen for vacuum leaks.
    • Inspect the entire intake air system from the mass air flow (MAF) sensor to the intake manifold for leaks such as:
      • damaged or loose IAC air tubes.
      • cracked or punctured intake air tube.
      • loose intake air tube at the air cleaner housing or throttle body.
      • IAC valve or gasket seal.
      • EGR valve gasket seal.
      • vacuum supply connector and hose.
      • PCV valve, connectors and hoses.
    • Are any leaks present? 
    Yes No
    REPAIR as necessary.
    CLEAR the DTCs. REPEAT the self-test.    		 GO to  KE3.
  3. KE3 CHECK FOR VOLTAGE TO THE IAC SOLENOID 
    NOTE: If EGR DTC P0402 is output during the self-test, diagnose it first before continuing with this pinpoint test.
    • IAC connector disconnected.
    • Key ON, engine OFF.
    • Measure the voltage between:
      ( + ) IAC Connector, Harness Side ( - ) Vehicle Battery
      PWR Negative terminal
    • Is the voltage greater than 10 V? 
    Yes No
    GO to  KE4. REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.
  4. KE4 CHECK THE RESISTANCE OF THE IAC VALVE 
    • Key in OFF position.
    • IAC connector disconnected.
    • Measure the resistance between:
      ( + ) IAC Connector, Component Side ( - ) IAC Connector, Component Side
      PWR IAC
    • Is the resistance between 6 ohms - 15 ohms? 
    Yes No
    GO to  KE5. INSTALL a new IAC valve. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article.
    CLEAR the DTCs. REPEAT the self-test.
  5. KE5 CHECK THE IAC VALVE FOR AN INTERNAL SHORT TO THE IAC CASE 
    • Measure the resistance between:
      ( + ) IAC Connector, Component Side ( - ) IAC Connector, Component Side
      IAC IAC Case
    • Is the resistance greater than 10K ohms? 
    Yes No
    GO to  KE6. INSTALL a new IAC valve. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article.
    CLEAR the DTCs. REPEAT the self-test.
  6. KE6 CHECK THE IAC CIRCUIT FOR AN OPEN IN THE HARNESS 
    • IAC connector disconnected.
    • PCM connector disconnected.
    • Measure the resistance between:
      ( + ) IAC Connector, Harness Side ( - ) PCM Connector, Harness Side
      IAC IAC
    • Is the resistance less than 5 ohms? 
    Yes No
    For IAC-RC applications, GO to  KE7.
    For all others, GO to  KE8.    		 REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.
  7. KE7 CHECK IAC-RC FOR VOLTAGE 
    • Measure the voltage between:
      ( + ) PCM Connector, Harness Side ( - )
      IAC-RC Ground
    • Is the voltage greater than 10 V? 
    Yes No
    GO to  KE8. REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.
  8. KE8 CHECK THE IAC CIRCUIT FOR A SHORT TO VOLTAGE IN THE HARNESS 
    • Key ON, engine OFF.
    • Measure the voltage between:
      ( + ) PCM Connector, Harness Side ( - ) Vehicle Battery
      IAC Negative terminal
    • Is the voltage less than 1 V? 
    Yes No
    GO to  KE9. REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.
  9. KE9 CHECK THE IAC CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS 
    • Key in OFF position.
    • Measure the resistance between:
      ( + ) PCM Connector, Harness Side ( - )
      IAC Ground
    • Is the resistance greater than 10K ohms? 
    Yes No
    GO to  KE10. REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.
  10. KE10 CHECK FOR A DROP IN IDLE RPM WITH THE IAC DISCONNECTED 
    • PCM connector connected.
    • IAC connector connected.
    • Key ON, engine running.
    • Bring the engine to normal operating temperature.
    • Transmission in PARK or NEUTRAL.
    • Disconnect the IAC valve.
    • Does the RPM drop or the engine stall? 
    Yes No
    GO to  KE12. GO to  KE11.
  11. KE11 CHECK FOR A STUCK IAC PINTLE 
    • Key in OFF position.
    • Inspect the entire intake air system for debris, blockage or other damage.
    • Remove and inspect the IAC valve and check the pintle movement.
    • Check the air tubes (if equipped) for blockage or damage.
    • Remove and inspect the air cleaner element for excessive dirt.
    • Is the IAC valve OK? 
    Yes No
    GO to  KE12. INSTALL a new IAC valve. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article.
    CLEAR the DTCs. REPEAT the self-test.
  12. KE12 VERIFY THE DTC 
    • Is DTC P0511 or P1504 present in continuous memory or from the KOER self-test? 
    Yes No
    GO to  KE22. GO to  KE13.
  13. KE13 CHECK THE IAC SIGNAL FROM THE PCM 
    NOTE: If stalling occurs, place a shim under the hard stop screw to maintain idle conditions.
    NOTE: With the engine at normal operating temperature, closed throttle and all accessories off, the IAC duty cycle should be between approximately 22% and 65%.
    • PCM connector connected.
    • IAC connector connected.
    • Key ON, engine running.
    • Access the PCM and monitor the RPM PID.
    • Access the PCM and monitor the IAC PID.
    • Slowly increase the engine speed to 3,000 RPM and return to closed throttle. (Note: If closed throttle RPM is significantly higher than normal, ignore this step).
    • Is the duty cycle between 22 - 65%? 
    Yes No
    GO to  KE14. INSTALL a new IAC valve. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article.
    CLEAR the DTCs. REPEAT the self-test.
  14. KE14 VERIFY THE DTC 
    • Is DTC P0506, P0511, P1504 or P1507 present in continuous memory? 
    Yes No
    GO to  KE20. INSPECT the throttle body for damage. REPAIR as necessary. If OK, INSTALL a new IAC valve. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article. RESET the keep alive memory (KAM). REFER toRESETTING THE KEEP ALIVE MEMORY (KAM) .
  15. KE15 DTCS P0507 OR P1506: CHECK FOR INLET AIR LEAKS 
    • Key ON, engine running.
    • With the engine running at idle, listen for vacuum leaks.
    • Inspect the entire intake air system from the mass air flow (MAF) sensor to the intake manifold for leaks such as:
      • damaged or loose IAC air tubes.
      • cracked or punctured intake air tube.
      • loose intake air tube at the air cleaner housing or throttle body.
      • IAC valve or gasket seal.
      • EGR valve gasket seal.
      • vacuum supply connector and hose.
      • PCV valve, connectors and hoses.
    • Are any leaks present? 
    Yes No
    REPAIR as necessary.
    CLEAR the DTCs. REPEAT the self-test.    		 GO to  KE16.
  16. KE16 CHECK FOR EVAP DTCS 
    NOTE: EVAP system malfunctions can cause IAC DTCs or idle speed concerns.
    • Are any EVAP DTCs present? 
    Yes No
    DISREGARD the current diagnostic trouble code (DTC) at this time. DIAGNOSE the next DTC. GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS . GO to  KE17.
  17. KE17 CHECK THE IAC VALVE FOR CORRECT FUNCTION 
    • Key ON, engine running.
    • Bring the engine to normal operating temperature.
    • Transmission in PARK or NEUTRAL.
    • Disconnect the IAC Valve.
    • Does the RPM drop or the engine stall? 
    Yes No
    GO to  KE18. INSPECT the throttle body for damage. REPAIR as necessary. If OK, INSTALL a new IAC valve. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article. RESET the keep alive memory (KAM). REFER toRESETTING THE KEEP ALIVE MEMORY (KAM) .
    CLEAR the DTCs. REPEAT the self-test.
  18. KE18 CHECK THE IAC CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS 
    NOTE: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.
    • Key in OFF position.
    • Scan tool connector disconnected.
    • PCM connector disconnected.
    • Measure the resistance between:
      ( + ) PCM Connector, Harness Side ( - ) Vehicle Battery
      IAC Negative terminal
    • Is the resistance greater than 10K ohms? 
    Yes No
    GO to  KE19. REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.
  19. KE19 VERIFY THE SYMPTOM 
    • Is a fast idle symptom currently present? 
    Yes No
    GO to  KE22. GO to  KE20.
  20. KE20 CHECK THE IAC SYSTEM FOR AN INTERMITTENT OPEN OR SHORT 
    • PCM connector connected.
    • Key ON, engine running.
    • Access the PCM and monitor the IAC and RPM PIDs.
    • With the engine at normal operating temperature, closed throttle and all accessories off, the IAC duty cycle should be between approximately 22% and 65%.
    • Observe the PIDs while carrying out the following at idle:
      • Lightly tap on the and wiggle the harness connector to simulate road shock.
      • Grasp the vehicle harness closest to the IAC valve. Shake and bend a small section of the harness from the IAC to the bulkhead and from the bulkhead to the PCM.
    • Do the IAC or RPM PIDs suddenly change in value, indicating a concern? 
    Yes No
    ISOLATE the concern. REPAIR as necessary.
    CLEAR the DTCs. REPEAT the self-test.    		 GO to  KE21.
  21. KE21 VERIFY THE SYMPTOM 
    • Is an idle quality, starting or stalling symptom currently present? 
    Yes No
    INSTALL a new IAC valve. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article.
    CLEAR the DTCs. REPEAT the self-test.    		 RETURN to the SYMPTOM CHARTS article, Symptom Charts for further direction.
  22. KE22 CHECK FOR CORRECT PCM OPERATION 
    • Disconnect all the PCM connectors.
    • Visually inspect for:
      • pushed out pins
      • corrosion
    • Connect all the PCM connectors and make sure they seat correctly.
    • Carry out the PCM self-test and verify the concern is still present.
    • Is the concern still present? 
    Yes No
    INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) . The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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