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Diagnostic Aids

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

If there is an impending failure, the system may require more time to run the diagnostic than was allotted in the system set procedure. If any DTCs do not run and no DTC is set, review the appropriate scan tool data list and service information. This will give an indication of why the DTCs do not run. Some may abort due to changes in the conditions while running. For example, changes in engine load such as a cooling fan or A/C compressor clutch turning ON, may cause a DTC to abort. If the EGR I/M System Status does not update to YES, the procedure can be repeated until a YES status is achieved.

Inspection/Maintenance (I/M) Exhaust Gas Recirculation (EGR) System Set Procedure

Step Action Yes No
1 Did you perform the Inspection/Maintenance (I/M) System Check? Go to Step 2  Go to Inspection/Maintenance (I/M) System Check 
2
  1. Ensure that the vehicle is within the Conditions for Running specified in the supporting text.
  2. Turn OFF all of the accessories, e.g., A/C, blower fan, etc.
  3. Start and allow the engine to idle for 2 minutes.
  4. Observe the I/M System Status display with a scan tool.
Did the Exhaust Gas Recirculation (EGR) System Status update to YES?		 Go to Step 5  Go to Step 3 
3 Observe the DTC Information with a scan tool.
Does the scan tool indicate any failed DTCs?		 Go to Diagnostic Trouble Code (DTC) List Go to Step 4 
4
  1. Refer to Inspection/Maintenance (I/M) System DTC Table  to determine which DTCs are required to run in order to update the EGR I/M System Status to YES.
  2. Observe the Not Ran Since Code Cleared display with a scan tool.
  3. Determine which of the DTCs required for a YES status has not run.
  4. Enter the DTC number in the Specific DTC menu of the scan tool.
  5. Operate the vehicle within the Conditions for Running the DTC, located in the supporting text for the diagnostic table of the DTC.
  6. Repeat numbers 4 and 5 of this step for any additional required DTCs that have not run.
  7. Observe the I/M System Status display with a scan tool.
Did the EGR System Status update to YES?		 Go to Step 5  Go to Diagnostic Aids
5 Observe the Emission Related DTC portion of the I/M System Status display with a scan tool.
Does the scan tool indicate any Emission Related DTCs set?		 Go to Diagnostic Trouble Code (DTC) List System OK
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