Manifold Absolute Pressure (MAP) Sensor (Except Prizm GSi)

MAP sensor connects to ECM by a wiring harness and to engine by a manifold vacuum hose. The ECM supplies a 5-volt reference signal to MAP sensor. The MAP sensor voltage varies according to changes in engine load (manifold vacuum). The ECM interprets voltage change as a change in the engine load and uses signal to help determine control of fuel injector, shift indicator light (if equipped), idle speed control solenoid (Metro) and EGR solenoid.