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SMU - Revised Inspection/Maintenance (I/M) Evaporative Emission (EVAP) System Set Procedure

Subject:Revised Inspection/Maintenance (I/M) Evaporative Emission (EVAP) System Set Procedure

Models:2004 Buick Rainier
2003-2004 Cadillac Escalade Models
2003-2004 Chevrolet Astro Van, Avalanche, Blazer, Express, Silverado, S-10, SSR, Suburban, Tahoe, TrailBlazer Models
2003-2004 GMC Envoy Models, Jimmy, Safari, Savana, Sierra, Sierra Denali, Sonoma, Yukon Models
2003-2004 Isuzu Ascender, NPR/NQR Commercial Models
2003-2004 HUMMER H2
with 4.3L, 4.8L, 5.3L, 6.0L Engine (VINs X, V, T, P, Z - RPOs LU3, LR4, LM7, LM4, L33, L59, LQ4, LQ9)


This bulletin is being issued to revise the Inspection/Maintenance (I/M) Evaporative Emission (EVAP) System Set Procedure in the Engine Controls sub-section of the Service Manual. Please replace the current information in the Service Manual with the following information.

The following information has been updated within SI. If you are using a paper version of this Service Manual, please make a reference to this bulletin on the affected page.

Inspection/Maintenance (I/M) Evaporative Emission (EVAP) System Set Procedure

Description

The purpose of this procedure is to satisfy the enable criteria necessary to execute inspection/maintenance (I/M) readiness diagnostics for the Evaporative Emission (EVAP) System. The procedure may be used to set the EVAP I/M System Status display on the scan tool to YES. The EVAP I/M System Status display indicates whether or not the control module has completed the readiness diagnostics. The readiness diagnostics complete when all DTCs comprising the diagnostics run and pass, or any DTC comprising the diagnostics illuminates the malfunction indicator lamp (MIL). If the diagnostics pass during one drive cycle, seventeen hours must elapse, regardless of whether the vehicle is driven or not. Then, the diagnostics will run again during the next drive cycle in which the conditions for running are met. Once the diagnostics have passed during the third drive cycle, the EVAP I/M System Status display will be updated to YES. A failed or aborted diagnostic will require the vehicle to cool down in order to meet the enable criteria for another drive cycle. Therefore, performing a visual inspection prior to running the EVAP test may prevent having to repeat the drive cycle.

Conditions for Running

    • At least 17 hours have elapsed since the last drive cycle met the Conditions for Running.
    • The difference between the startup engine coolant temperature (ECT) and the startup intake air temperature (IAT) is less than 8°C (14.4°F).
    • The barometric pressure (BARO) is more than 74 kPa.
    • The startup ECT is between 4-30°C (39-86°F).
    • The fuel level is between 15-85 percent.
    • The battery voltage is between 10-18 volts.
    • The fuel level does not increase more than 9 percent during this drive cycle.
    • The engine run time is at least 10 minutes.
    • The vehicle has been driven at least 5 km (3.15 miles) this drive cycle.
    • The estimated ambient temperature at the end of this drive cycle is between 2-32°C (36-89°F).
    • The shutdown ECT is at least 70°C (158°F).
    • The ignition is turned OFF for at least 1 hour after this drive cycle.

Diagnostic Aids

Extreme high or low ambient temperatures may prevent the EVAP System Tests from initiating. A loose fuel cap may cause a test to abort or fail and prevent the I/M System Status from updating. A failed or aborted diagnostic will require the vehicle to cool down in order to meet the enable criteria for another drive cycle.

If there is an impending failure, the system may require more time to run the diagnostic than was allotted in the set procedure. If the diagnostic does not run after numerous attempts and no DTC is set, review the appropriate scan tool data list and the service information. This will give an indication of why the test does not complete. Some diagnostics may abort due to changes in the conditions while the test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning ON, may cause the diagnostic to abort.

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

    Important: At least 3 drive cycles, with a minimum of 17 hours between drive cycles, are required for the EVAP System Status to update to YES. Repeat Steps 1-9 until the minimum requirement of drive cycles is met.

  1. Ensure 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. Important: Once the engine is started, DO NOT turn the engine OFF for the remainder of the procedure.

  3. Start the engine and idle for 2 minutes.

    4. Caution: Refer to Road Test Caution in Cautions and Notices.

  4. Accelerate at part throttle to 72 km/h (45 mph) with this speed maintained until the engine reaches operating temperature. This may be up to 10 minutes depending on the start up coolant temperature.
  5. Continue the operating conditions for an additional 6 minutes after the engine reaches operating temperature.
  6. Decelerate to 0 km/h (0 mph).
  7. Allow the engine to idle for 2 minutes.

    8. Important: Ensure that the ignition remains OFF for 1 hour in order for the control module to perform vacuum testing.

  8. Turn OFF the ignition for 1 hour.
  9. Turn ON the ignition after 1 hour.

Did the EVAP 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 complete this diagnostic.
  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. Ensure that the vehicle is within the Conditions for Running the DTC, located in the supporting text for the diagnostic table of the DTC.
  6. Repeat the procedure in step 2 of the inspection/maintenance (I/M) evaporative emission (EVAP) system set procedure until the scan tool indicates the DTC has run.
  7. Repeat steps 4-6 for any additional required DTCs that have not run.
  8. Observe the I/M System Status display with a scan tool.

Did the EVAP 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