See Figures 1, 2 and 3
The first Subaru electronic ignition system was introduced in the late 1970's. Since that time, production changes have been made from year to year, but the basic design has remained the same. All 1.2L, 1.6L, 1.8L and 2.7L models are equipped with electronic ignition systems.
The electronic ignition system differs from a points type ignition only in the manner in which the spark is triggered. The secondary side of the ignition system is the same as a points type system.
Located in the distributor, is a four spoke rotor (reluctor) which rests on the distributor shaft where the breaker points are normally found. A pickup coil, consisting of a magnet, coil and wiring, rests on the breaker plate next to the reluctor.
When a reluctor spoke is not aligned with the pickup coil, it generates large lines of flux between itself, the magnet and the pickup coil. This large flux variation results in a high generated voltage in the pickup coil. When a reluctor spoke lines up with the pickup coil, the flux variation is low, thus allowing current to flow to the pickup coil. The ignition primary current is then cut off by the electronic unit, allowing the field in the ignition coil to collapse. The collapse of the ignition coil induces a high secondary voltage in the conventional manner. The high voltage then flows through the distributor to the spark plug, as usual.
The systems also use a transistorized ignition unit mounted above the ignition coil.
The 1.2L carbureted and fuel injected engine is equipped with a newly designed electronic advance angle igniter. The igniter has no mechanical frictional parts. It features vibration proofing, a high level of ignition timing accuracy and minimal quality changes with operation.
The ignition system consists of a magnetic pickup, built into the distributor, a control unit, an ignition coil and other related components. The magnetic pickup consists of a reluctor, which rotates in relation to the crankshaft, and a pickup coil. The power transistor, which controls current flow of the coil primary circuit, is housed in the control unit.
The magnetic pickup detects the crankshaft angle and sends a corresponding signal to the operation circuit of the control unit. This determines the optimum length of current flow to the primary circuit of the ignition coil and ignition timing (equivalent to governor advance angle). Current to the primary circuit of the ignition coil is made and broken by the power transistor of the control unit used as a switching control.