The 1995 Toyota 4Runner ignition system consist of electronics control module (ECM), igniter, ignition coil, distributor and pickup coils.
The ECM is programmed with data for optimum ignition timing under fail operating conditions. Using data provided by sensors which monitor various engine functions (RPM, intake air volume, engine coolant temperature, etc.), the microcomputer (ECM) triggers the spark at precisely the right instant. The ECM monitors the engine condition by signals from each sensor, calculates the ignition timing and sends an ignition signal to the igniter. High voltage from the ignition is distributed to each spark plug in the appropriate order to generate a spark between the electrodes, which ignites the air–fuel mixture.
The igniter temporarily interrupts the primary current with the ignition signal (lGT signal) from the ECM and generates sparks at the spark plug. Also, as a fail–safe measure, when ignition occurs an ignition confirmation signal (lGF signal) is sent to the ECM.
The ignition coil uses a closed core coil with the primary coil wrapped around the core and the secondary coil wrapped around the primary coil. This allows the generation of a high voltage sufficient to cause a spark to jump across the spark plug gap.
The distributor distributes high voltage to the spark plug of each cylinder in the specified ignition order.
The Pickup coil detects the crankshaft position, and the G 1 and G2 coils detect the camshaft position.