Manifold Absolute Pressure (MAP) Sensor

MAP sensor is connected to ECM/PCM by a 3-wire harness and to engine by a manifold vacuum hose. MAP sensor has an internal mechanical resistor which varies resistance based on changes in engine load (manifold vacuum). As internal resistance varies, return voltage signal to ECM/PCM varies. ECM/PCM interprets this voltage change as changes in engine load and uses this signal to help determine control of fuel injectors and other various sensors and switches.