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For 1990-2009 cars only
Makes 🢒 Buick 🢒 2005 🢒 Terraza 🢒 Engine 🢒 Engine Controls - 3.5L (LX9) 🢒 Inspection/Maintenance (I/M) Exhaust Gas Recirculation (EGR) System Set Procedure

Description

The purpose of this test is to satisfy the enable criteria necessary to execute inspection/maintenance (I/M) readiness diagnostics for the exhaust gas recirculation (EGR) system. The test may be used to set the I/M System Status indicators to YES. The I/M System Status display on the scan tool provides an indication of whether the control module has completed the required tests. The I/M System Status does not indicate that the tests have passed or failed. When all of the diagnostics for a specific system have run and passed, the I/M System Status will update to YES. If a test for a specific system has failed, the I/M System Status will update to YES, indicating a determination was made even if all of the other tests for that system have not run.

Conditions for Running
    • The vehicle speed sensor (VSS) is between 45-112 km/h (28-20 mph).
    • The barometric pressure (BARO) is more than 74 kPa.
    • The manifold absolute pressure (MAP) sensor parameter does not change more than 1.1 kPa.
    • The traction control is not active.
    • The ignition 1 voltage is between 11-18 volts.
    • The intake air temperature (IAT) is between -7 and +100°C (+20 and +212°F).
    • The A/C Relay Command parameter does not change.
    • The Current Gear parameter does not change.
    • The engine coolant temperature (ECT) is between 75-126°C (167-258°F).
    • The engine speed is between 1,000-1,500 RPM.
    • The manifold absolute pressure (MAP) is between 17-43 kPa.
    • The engine is not running in Decel Fuel Cutoff mode.
    • The EGR position is less than 1 percent.
    • The throttle position (TP) sensor is less than 1 percent.
    • The vehicle speed is more than 45 km/h (28 mph) during deceleration.

Diagnostic Aids

The control module only runs the EGR Active Tests during a gradual deceleration with a closed throttle and a vehicle speed above 48 km/h (30 mph). Several deceleration cycles may be necessary in order to accumulate a sufficient number of EGR flow samples. The procedure outlined in the table is for a clear, flat road. If the procedure is performed on a road with a slight down hill grade, the test may acquire the necessary sample counters in one or 2 decel trips. If the test is interrupted during the procedure, it may take more than three deceleration cycles to complete the test. If the status does not update, the test outlined in this procedure can be repeated until the I/M System Status updates to YES.

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 test does not run after numerous attempts and no DTC is set, review the appropriate scan tool data list and the service information for an indication of why the test does not complete. Some tests 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 A/C compressor clutch turning ON may cause the test to abort.

If a diagnostic test is difficult to run, observe the I/M System Status display while maintaining the necessary enable conditions until the System Status updates to YES.

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 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 the engine and allow it to idle for 2 minutes.

    4. Caution: Refer to Road Test Caution in the Preface section.

    Important:  In order for this test to run, the vehicle must operate in the following conditions:

       • Acceleration at part throttle to 89 km/h (55 mph) with this speed maintained for 1 minute
       • Decelerate to 45 km/h (28 mph) while the following criteria is maintained:
          - The throttle is closed.
          - There is NO brake application.
          - There is NO clutch actuation on a manual transmission.
          - There is NO manual downshift.

  4. 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 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 - Vehicle in Vehicle DTC Information

Go to Step 4

4

  1. Refer to the Inspection/Maintenance (I/M) System DTC Table to determine which DTCs are required to run in order to complete this test.
  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 the procedure until the scan tool indicates the diagnostic test has run. This may take up to 2 hours.
  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 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 - Vehicle in Vehicle DTC Information

System OK