Manifold Absolute Pressure (MAP) Sensor

MAP sensor is connected to control unit by a 3-wire harness and to engine by a manifold vacuum hose. Control unit applies a 5-volt voltage reference signal from terminal "A23" of control unit to MAP sensor. MAP sensor has an internal mechanical resistor which varies resistance based upon changes in engine load (manifold vacuum). As internal resistance varies, return voltage signal varies at terminal "A22" of control unit. Control unit interprets this voltage change as changes in engine load and uses this signal to help determine control of fuel injector, idle speed control solenoid and EGR system.

With key on and engine off, MAP sensor signal is interpreted by the control unit as a Barometric (BARO) pressure signal. BARO signal is used by control unit to determine control of timing and air/fuel mixture.