Manifold Absolute Pressure (MAP) Sensor

The manifold absolute pressure (MAP) sensor senses atmospheric pressure to produce an electrical signal. The frequency of this signal varies with intake manifold pressure. The powertrain control module (PCM) monitors this signal to determine altitude. The PCM then adjusts the transmission shift schedule and EPC pressure for altitude. On diesel engines, the MAP sensor measures boost pressure. The PCM monitors this signal and adjusts EPC pressure.