evap system monitor switch 2007 dodge ram

The switch closure sends a signal to the PCM. When the vacuum in the system exceeds about 1” H20, the vacuum switch closes. system is sealed, it will be pulled into a vacuum, either due to the cool down from operating temperature or diurnal ambient temperature cycling. The ESIM conducts test on the evaporative system as follows: An engine off, non-intrusive test for small leaks and an engine running, intrusive test for medium/large leaks. When a calibrated amount of vacuum is achieved in the evaporative system, the diaphragm is pulled inward, pushing on the spring and closing the contacts. 5 inches of water, the large check valve unseats and pressure vents to the fresh air filter.Ĭonversely, when the system cools, and the resulting vacuum lifts the small check valve from its seat and allows fresh air to enter the system and relieves the vacuum condition. The larger check valve seals for pressure and the smaller one seals for vacuum.ĭuring refueling, pressure is built up in the evaporative system. The ESIM consists of housing, two check valves (sometimes referred to as weights), a diaphragm, a switch and a cover. The ESIM has been simplified because the solenoid used on the NVLD is not used on the ESIM. The ESIM (Evaporative System Integrity Monitor), while physically different than the NVLD system, performs the same basic function as the NVLD does – controlling evaporative emissions. The weighted check valves are contained within the ESIM housing. The small weight check valve seals for vacuum. The large weight check valve seals for pressure. A seal is attached at the end of each weighted check valve. There is one large weight and one small weight check valve in the ESIM assembly. The ESIM assembly consists of a housing, a small weight and a large weight that serve as check valves, a diaphragm, a switch and a cover. When the ESIM is installed vertically, the electrical connector is in the 3 o'clock position. On vehicles where the canister is mounted on an angle, the ESIM requires an adaptor to maintain a vertical position. It is critical that the ESIM is mounted vertically. The ESIM mounts directly to the canister, eliminating the need for a mounting bracket. However, the design of the ESIM has been simplified and unlike the NVLD the ESIM does not require a solenoid.

The ESIM (Evaporative System Integrity Monitor) is very similar to the NVLD.

Evap system monitor switch 2007 dodge ram