Inspection/Maintenance Evaporative Emission System Set
Inspection/Maintenance Evaporative Emission System Set
Description
The purpose of this procedure is to satisfy the enable criteria necessary in order to execute the inspection/maintenance (I/M) readiness diagnostics for the Evaporative Emission (EVAP) System. Ensure the vehicle meets the requirements listed in Conditions for Running before performing this test. Failure to meet the necessary requirements may produce inaccurate test results.
Conditions for Running
* Three or more drive cycles with a minimum of 17 hours between cycles
* The difference between the start-up engine coolant temperature (ECT) and the start-up intake air temperature (IAT) is less than 8°C (14.4°F).
* The barometric pressure (BARO) is more than 74 kPa.
* The start-up ECT is between 4-30°C (39-86°F).
* The start-up IAT 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 estimated ambient temperature at the end of this drive cycle is between 2-32°C (36-89°F).
* The shutdown ECT is 70°C (158°F) or higher.
* A refueling event is not detected.
Diagnostic Aids
Extreme high or low ambient temperatures may prevent DTCs from initiating. Rough road conditions, a damaged or improperly connected fuel cap, and high fuel volatility may cause DTCs to abort or fail. High fuel volatility usually means that the fuel in the vehicle has a higher volatility than what is appropriate for the ambient temperatures. This can occur when winter fuel is used during warm temperatures.
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 diagnostic trouble code (DTC) portion of the I/M System Status display will indicate the MIL is requested. The I/M System Status also registers the number of 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 the 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 review 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 the engine load, such as a cooling fan or an 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.
Test
