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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 85 (Engine Controls - Self-Diagnostics - 8.1L) >> Diagnostic Tests >> DTC P0506 & P0507: Idle Control System - Low Or High Rpm >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page does not describe the selected car, but rather 13 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Sierra, 2002 GMC Savana Special, 2002 GMC Savana Camper Special, and 2002 GMC Savana. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Start the engine. With the RPM control function of the scan tool, command the engine RPM to 1500 RPM, to 500 RPM, and back to 1500 RPM. Exit the RPM Control function. Did the engine speed stay within 100 RPM of the commanded RPM during the above test? If yes, see DIAGNOSTIC AIDS . If no, go to next step.
  3. Is the engine RPM 100 RPM more than the desired RPM? If yes, go to next step. If no, go to step  5.
  4. Inspect for the following conditions:
    • Vacuum leaks.
    • Excessive deposits in the throttle body.
    • A faulty Positive Crankcase Ventilation (PCV) valve.

    Repair as necessary. After repairs, go to step  6.

  5. Inspect for energy draining load on the engine, such as ones caused by transmission conditions. Repair as necessary. After repairs, go to next step.
  6. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  7. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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