Powertrain Control Module (Pcm)

PCM is a digital computer that controls ignition timing, air/fuel ratio, emission control devices, cooling fan, charging system, idle speed, cruise control (if equipped), fuel pump and tachometer. The control unit is located in engine compartment. PCM uses data from various input sources to control output devices in order to achieve optimum engine performance for all operating conditions.

PCM has voltage converters that convert battery voltage to regulated 5-volt and 8-volt outputs. The 8-volt output powers vehicle speed sensor, Camshaft Position (CMP) sensor and Crankshaft Position (CKP) sensor. The 5-volt output powers coolant temperature sensor, throttle body temperature sensor, Manifold Absolute Pressure (MAP) sensor and Throttle Position Sensor (TPS).

NOTE: Components are grouped into 2 categories. The first category, INPUT DEVICES, includes components that control or produce voltage signals monitored by the PCM. The second category, OUTPUT SIGNALS, includes components controlled by the PCM (this is accomplished by the PCM grounding individual circuits).