Manifold Absolute Pressure (MAP) Sensor

MAP sensor is connected to ECM by a wiring harness and to engine by a manifold vacuum hose. ECM supplies a 5-volt reference signal, a bias voltage and a ground to MAP sensor. MAP sensor voltage varies according to changes in engine load and engine RPM (manifold vacuum). Low voltage signal indicates low manifold pressure and high voltage indicates high manifold pressure. ECM uses voltage signal to control fuel volume available.

MAP sensor is used to measure barometric pressure, which allows ECM to automatically adjust for different altitudes and to control ignition timing.