EVAP System Set Procedure
Inspection/Maintenance (I/M) Evaporative Emission (EVAP) System Set Procedure
Description
The purpose of this test is to satisfy the enable criteria necessary to execute I/M readiness diagnostics for the evaporative emission (EVAP) system. The test may be used to set the I/M System Status indicators to YES. Service Bay Tests are included on the scan tool for some systems depending upon vehicle make and model. The test is designed to allow the EVAP Diagnostic Tests to run in service bay conditions.
Conditions for Running
Non Scan Tool Service Bay Test Equipped Vehicles
- The barometric pressure is more than 75 kPa.
- The fuel level is between 1/4 and 3/4.
- The battery voltage is between 10-18 volts.
- The test will initiate only after a cold start. The control module considers the engine to be cold if the following conditions are met:
- The engine coolant temperature (ECT) is between 3.75-30°C (39-86°F).
- The intake air temperature (IAT) is between 3.75-30°C (39-86°F).
- The difference between the ECT and the IAT is less than 8°C (14°F).
Scan Tool Service Bay Test Equipped Vehicles
- The barometric pressure (BARO) is more than 75 kPa.
- The ECT is less than 80°C (176°F).
- The fuel level is between 1/4 and 3/4.
- The battery voltage is between 10-18 volts.
Diagnostic Aids
Extreme high or low ambient temperatures may prevent the EVAP System Tests from initiating. Performing a visual inspection prior to running the EVAP Service Bay Test may prevent having to repeat the test. A loose fuel cap may cause a Service Bay Test to abort or fail and prevent the I/M System Status from updating. A failed or aborted test will require the vehicle to cool down in order to meet the enable criteria to run another test.
The I/M System Status does not indicate whether the test has passed or failed, only that a decision was made. 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 required tests have not run. When a failure occurs, the Emission Related DTC portion of the I/M System Status display will indicate the malfunction indicator lamp (MIL) is requested. The I/M System Status also registers the number of diagnostic trouble codes (DTCs).
The first failure of a type B DTC does not constitute a final determination of pass or fail, and will not update the I/M System Status to YES. A second trip is required, and all the conditions to run must be met in order for the test to run again. These conditions may include a partial to complete engine cool down.
The I/M System Status will update only when an emission related DTC fails the second time, or when all of the tests pass.
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 an AC compressor clutch turning ON, may cause the test to abort.
If a diagnostic test is difficult to run, maintain necessary enable conditions until the system status updates to YES.
