Vacuum Switch: Description and Operation

MAP VSV CONTROL
ECM turns MAP VSV "ON" for about 1 second for about 1 second under the following three conditions, to switch MAP sensor input signal to the atmospheric pressure.
1) When ECM is reset.
2) The following three conditions occur at the same time.
- Engine speed is less than 200 rpm.
- Battery voltage is more than 9.5 V.
- Vehicle speed is less than 1 km/h.
3) When ECM judges the high altitude condition, ECM turns MAP VSV "ON", to get the atmospheric pressure, and sets "BAROMETRIC MAP".
The specification of high altitude;
"BAROMETRIC MAP" is less than 596 mmHG abs.