Manifold Pressure/Vacuum Sensor: Description and Operation

PURPOSE

The Manifold Atmospheric Pressure (MAP) Sensor measures intake manifold vacuum. The Engine Control Module (ECM) uses this information to determine engine load.

CONSTRUCTION

The sensor contains a silicon diaphragm covering a small vacuum port. When vacuum is applied, the diaphragm flexes which causes a low voltage signal to be generated. An internal circuit amplifies the signal to produce a higher voltage back to the ECM.

OPERATION

Whenever the ignition is ON, the sensor produces a readable voltage. The voltage varies dependant upon the amount of vacuum present at the sensing port.