Manifold Pressure/Vacuum Sensor: Description and Operation

Voltage Versus Pressure Chart:

DESCRIPTION
The Manifold Absolute Pressure (MAP) sensor is a potentiometer that measures the changes in intake manifold pressure due to engine speed and load changes. The Powertrain Control Module (PCM) supplies a 5 volt reference signal and a ground to the MAP sensor and the sensor in turn sends a voltage signal to the PCM.

OPERATION
As manifold pressure increases (vacuum decreases), the voltage signal increases and as manifold pressure decreases (vacuum increases), the voltage signal decreases. A high pressure signal will be close to 5 volts and a low pressure signal will be close to 0 volt.