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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 413 (Engine Controls - Self Diagnostics - 8.1L) >> Drive Cycles >> Inspection/Maintenance Exhaust Gas RECIRCULATION (EGR) System Set Procedure >> Diagnostic Procedure

Diagnostic Procedure

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  1. Did you perform the Inspection/Maintenance (I/M) System Check? If YES, go to next step. If NO, see INSPECTION/MAINTENANCE SYSTEM CHECK .
    2. CAUTION: Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.
  2. In order for this test to run, the vehicle must operate in the following conditions:
    • Ensure the vehicle is within the Conditions for Running specified in the supporting text.
    • Turn OFF all of the accessories, e.g., A/C, blower fan, etc.
    • Start the engine and allow it to idle.
    • Acceleration at part throttle to 80 km/h (50 mph) with this speed maintained for 1 minute.
    • Four decelerations of 25 seconds each from 80 km/h (50 mph) while the following criteria is maintained:
      1. The throttle is closed.
      2. NO brake application on either manual or automatic transmission.
      3. NO clutch actuation on a manual transmission.
      4. NO manual downshift.
      5. The vehicle speed remains above 25 mph (40 km/h).
      6. After each deceleration period, the vehicle is returned to 50 mph (80 km/h) under part throttle acceleration and the speed is maintained for 15 seconds.
    • With a scan tool, observe the I/M System Status display. Did the EGR System Status update to YES? If yes, go to step  5. If no, go to next step.
  3. With a scan tool, observe the DTC Information. Does the scan tool indicate any failed DTCs? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  4. Refer to INSPECTION/MAINTENANCE SYSTEM DTCS  to determine which DTCs are required to run in order to complete this test. With a scan tool, observe the Not Ran Since Code Cleared display. Determine which of the DTCs required for a YES status has not run. Enter the DTC number in the Specific DTC menu of the scan tool. Operate the vehicle within the Conditions for Running the DTC, located in the supporting text for the diagnostic table of the DTC. Repeat the procedure until the scan tool indicates the diagnostic test has run. Repeat steps 4-6 for any additional required DTCs that have not run. With a scan tool, observe the I/M System Status display. Did the EGR System Status update to YES? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  5. With a scan tool, observe the Emission Related DTC portion of the I/M System Status display. Does the scan tool indicate any Emission Related DTCs set? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system okay.
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