Ignition Switch

Ignition switch sends signal to Engine Control Module/Powertrain Control Module (ECM/PCM) indicating whether switch is on, off or cranking (ST). When ECM/PCM receives ON signal, it energizes fuel pump relays and supplies power to sensors and actuators. When ECM/PCM receives ST signal, it controls fuel injection rate, idle speed, ignition timing, etc. for optimum cranking conditions.