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Home >> Buick >> 2004 >> Century Custom >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls 3.1L (Troubleshooting & Diagnosis) >> Engine Controls >> Inspection/Maintenance (I/M) Complete System Set Procedure >> Test Description

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  This step is to run the HO2S Heater Tests and initiate the EVAP System Test. Preprogramming the scan tool will reduce the amount of time the oxygen sensor heaters operate while verifying the enable criteria.
  2. 3:  This step is to run the EVAP, AIR and the Oxygen Sensor Tests. The EVAP Test begins once the engine coolant reaches a calibrated temperature. The AIR Test, if equipped, begins shortly after Closed Loop and the indicated speed is achieved. The Oxygen Sensor Tests begin once the engine is at operating temperature, in Closed Loop Fuel Control, and a calibrated amount of time has elapsed.
  3. 4:  This step is to run the EGR Tests. The EGR Tests are run during a gradual deceleration with a closed throttle. The vehicle speed is required in order to maintain a high, steady MAP signal.
  4. 5:  This step is to run the Catalyst Tests. This test runs during the idle period immediately following a cruise period that meets a minimum calibrated RPM and time period.
  5. 7:  The I/M System Status only reports on whether or not a diagnostic has run, not what the outcome of the test was. If any emission related DTC sets after the tests are complete, the DTC will require diagnosis.
Inspection/Maintenance (I/M) Complete System Set Procedure

Step Action Value(s) 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: Whenever the ignition is turned ON, ignition positive voltage is supplied to the HO2S heaters. After verifying the enable criteria, turn OFF the ignition for approximately 5 minutes to allow the sensors to cool before continuing with the test. Once the engine is started, DO NOT turn the engine OFF for the remaining portion of the set procedure.
  1. Preprogram the scan tool with the vehicle information before the ignition is turned ON.
  2. Ensure the vehicle is within the Conditions for Running specified in the supporting text.
  3. Turn OFF all of the accessories, e.g., A/C, blower fan, etc.
  4. Set the vehicle parking brake.
  5. Verify the transmission is in PARK for automatic transmissions and NEUTRAL for manual transmissions.
  6. Start the engine and allow it to idle for the specified time.
Is the action complete?		 2 minutes Go to Step 3  -
3 
CAUTION: Refer to Road Test Caution in Cautions and Notices.
In order for the next group of tests to run, the vehicle must operate in the following conditions:
  1. 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.
  2. Continue operation under these conditions for an additional 3 minutes
Is the action complete?		 - Go to Step 4  -
4 
CAUTION: Refer to Road Test Caution in Cautions and Notices.
In order for the next group of tests to run, the vehicle must operate in the following conditions:
  1. Accelerate to 89 km/h (55 mph) with this speed maintained for one additional minute.
  2. Decelerate to 48 km/h (30 mph) while the following criteria is maintained:
    • The throttle is closed.
    • There is NO brake application on either manual or automatic transmission.
    • There is NO clutch actuation on a manual transmission.
    • There is NO manual downshift.
Is the action complete?		 - Go to Step 5  -
5 
CAUTION: Refer to Road Test Caution in Cautions and Notices.
In order for the next group of tests to run, the vehicle must operate in the following conditions:
  1. Accelerate at part throttle to 90 km/h (55 mph) with this speed maintained for 5 minutes.
  2. Decelerate to 0 km/h (0 mph).
  3. The engine is idling for 2 minutes while the following criteria is maintained:
    • The service brake is pressed
    • The automatic transmission is in DRIVE.
    • The manual transmission is in NEUTRAL with the clutch pedal pressed.
Is the action complete?		 - Go to Step 6  -
6 Observe the I/M System Status display with a scan tool.
Did all of the I/M System Status indicators update to YES?		 - Go to Step 7  Go to the I/M System Set Procedure for the indicated systems that have not passed
7  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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