Pumping Action

During portions of this test, the PCM uses the reed switch to monitor diaphragm movement. The solenoid is only turned on by the PCM after the reed switch changes from open to closed, indicating that the diaphragm has moved down. At other times during the test, the PCM will rapidly cycle the LDP solenoid on and off to quickly pressurize the system. During rapid cycling, the diaphragm will not move enough to change the reed switch state. In the state of rapid cycling, the PCM will use a fixed time interval to cycle the solenoid.

If the system does not pass the EVAP Leak Detection Test, the following DTCs may be set:

• P0442 - EVAP LEAK MONITOR 0.040" LEAK DETECTED
• P0455 - EVAP LEAK MONITOR LARGE LEAK DETECTED
• P0456 - EVAP LEAK MONITOR 0.020" LEAK DETECTED
• P1486 - EVAP LEAK MON PINCHED HOSE FOUND
• P1494 - LEAK DETECTION PUMP SW OR MECH FAULT
• P1495 - LEAK DETECTION PUMP SOLENOID CIRCUIT