Evaporative Emission (EVAP) Leak Detection Control Module: Notes

The EVAP leak detection control module is mounted behind the fuel tank, near the EVAP canister and consists of a vacuum pump, a pressure sensor, a 0.02" reference orifice and a switching valve. The vacuum pump is used to apply a vacuum across the reference orifice and to apply a vacuum on the EVAP system for the EVAP leak check monitor. The 0.02" reference orifice is used to obtain a reference check for leak detection every time the EVAP monitor runs. The pressure sensor is used to determine the vacuum level across the reference orifice and for the EVAP leak detection monitor. The EVAP leak detection control module is vented to atmosphere through the switching valve and allows for purging during engine operation and refueling.