The following schematic shows Toyota Pickup Typical Ignition System Circuit Diagram. The ignition system consists of battery, ignition switch, spark plug, cap and rotor, distributor, ignition coil with igniter, signal rotor, pickup coil, igniter and ECM. The ECM is programmed with data for optimum ignition timing under any and all operating conditions. Using data provided by sensors which monitor various engine functions (rpm, intake air volume, engine temperature, etc.) the microcomputer (ECM) triggers the spark at precisely the right instant.