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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 250 (Engine Controls Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0507: Idle Speed High >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Pontiac Sunfire, 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, and 2003 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
    2. NOTE: Ensure engine speed stabilizes with each commanded RPM change to determine if engine speed stays within 200 RPM of commanded RPM.
  2. Set parking brake and block drive wheels. Install scan tool. Start the engine. Turn off all accessories. Use scan tool RPM control function to slowly increment engine speed to 1700 RPM, then to 600 RPM, then to 1700 RPM. Exit RPM control function. Does the engine speed stabilize within 200 RPM of the commanded RPM during the test? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC, and within the parameters observed in the Freeze Frame/Failure Records. Does the DTC fail this ignition? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  4. Turn ignition switch to OFF position. Disconnect IAC valve harness connector. Connect IAC Motor Driver (J 37027-A) to IAC valve. Start the engine. Use IAC motor driver to command IAC valve in until 600 RPM is reached. Use IAC motor driver to command IAC valve out until 1700 RPM is reached. Return engine to desired idle speed as indicated on scan tool data list. Did the engine speed steadily decrease to about 600 RPM and steadily increase to about 1700 RPM when the IAC valve was commanded in and out? If yes, go to next step. If no, go to step  11.
  5. Connect the test light between one of the IAC valve control circuits and a good ground. Start the engine. Observe the IAC Counts parameter using a scan tool and observe the test light. Command high RPM using the IAC Motor Driver until the IAC counts parameter starts to increment. Command low RPM using the IAC Motor Driver until the IAC Counts parameter starts to increment. Return the engine speed parameter to the desired idle speed parameter. Repeat the above procedure for the other three IAC valve control circuits. Did the test light remain ON, never flashing, while the IAC Counts were incrementing for any of the IAC valve control circuits? If yes, go to step  10. If no, go to next step.
  6. Did test light remained off (never flashing) while IAC counts were incrementing at any of IAC valve circuits during the test? If yes, go to step  9. If no, go to next step.
  7. Connect a test light between the IAC coil "A" low control circuit and the IAC coil "A" high control circuit. Observe the IAC counts parameter using a scan tool and observe the test light. Command high RPM using the AC Motor Driver until the IAC counts parameter starts to the increment. Command low RPM using the AC Motor Driver until the IAC Counts parameter starts to increment. Return the Engine Speed parameter to the Desired Idle Speed parameter as indicated on the scan tool data list. Repeat the above procedure using the test light connected between the IAC coil "B" low control circuit and the IAC coil "B" high control circuit. Did the test light stay illuminated and never flashing while the IAC Counts were incrementing for any of the IAC valve control circuits? If yes, go to next step. If no, go to step  16.
  8. Inspect for a poor connection at the IAC valve harness connector. Did you find and correct the condition? If yes, go to step  17. If no, go to step  12.
  9. Turn ignition switch to OFF position. Disconnect PCM harness connectors. Using a DMM, test the circuit where test light remained OFF for an open circuit, short to ground or short to another IAC valve circuit. Did you find and correct the condition? If yes, go to step  17. If no, go to step  12.
  10. Turn ignition switch to RUN position, engine off. Using a DMM, test the circuit where the test light remained ON for a short to voltage or short to another IAC valve circuit. Did you find and correct the condition? If yes, go to step  17. If no, go to step  12.
  11. Visually/Physically inspect for the following:
    • Throttle body damage and tampering.
    • Throttle lever screw tampering (if equipped).
    • Vacuum leaks.
    • Faulty, incorrectly installed PCV valve and hose (if equipped).
    • Throttle shaft binding.
    • Throttle linkage or cruise control linkage binding (if equipped).

    Remove IAC valve. Inspect for the following:

    • Debris in the IAC passage.
    • Excessive deposits on throttle plate.
    • Excessive deposits in throttle bore.
    • Excessive deposits on IAC valve pintle.

    Did you find and correct the condition? If yes, go to step  17. If no, go to step  14.

  12. Inspect for an intermittent and a poor connection at the PCM harness connectors. Did you find and correct the condition? If yes, go to step  17. If no, go to next step.
  13. Disconnect PCM harness connectors. Check all IAC valve control circuits for high resistance. Did you find and correct the condition? If yes, go to step  17. If no, go to step  16.
  14. Inspect for a poor connection at the IAC valve harness connector. Did you find and correct the condition? If yes, go to step  17. If no, go to next step.
  15. Replace IAC valve. When complete, go to step  17.
  16. Replace PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing PCM, go to next step.
  17. Using scan tool, clear the DTCs. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  18. Using a scan tool, observe the CAPTURE INFO. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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