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 barometric pressure is more than 74 kPa. |
| • | The ignition 1 voltage is between 11-18 volts. |
| • | The intake air temperature (IAT) is between 0-100°C (32-212°F). |
| • | The A/C Relay Command parameter does not change. |
| • | The Current Gear parameter does not change. |
| • | The engine coolant temperature (ECT) is more than 75°C (167°F). |
| • | The engine speed is between 1,050-1,400 RPM. |
| • | The manifold absolute pressure (MAP) is between 15-70 kPa. |
| • | The mass air flow (MAF) sensor does not change more than 2 grams per second. |
| • | The throttle position (TP) sensor is less than one percent. |
| • | The vehicle speed is more than 48 km/h (30 mph) during deceleration. |
| • | The idle air control (IAC) position does not change more than 5 counts when the above conditions are met. |
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 two 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 | |||||||||||||
2 |
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:
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 Step 4 | |||||||||||||
4 |
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? | System OK |
