Ignition System Types

Essentially, there are three commonly used methods to control the current flow through the coil primary winding. These are:


* Point-Based Ignition

* Electronic Ignition

* Computer Ignition


Point-Based Ignition

This system is the most basic, and was used widely until the mid-seventies, when most manufacturers switched to an electronic ignition system. Basically, the current to the coil primary is controlled by a mechanical switch (points) which is operated directly by the distributor shaft and thus synchronized with the piston positions. The following diagram illustrates this type of system:


Figure 2 typical point-based system diagram [1]


Electronic Ignition

The points-based system was modified by replacing the mechanical points with a power transistor. Some method of detecting engine position (usually a Hall-Effect Sensor mounted in the distributor) was used in order to switch the transistor. A separate module was used to do the switching, as shown in the following diagram:


Figure 3 typical electronic ignition system diagram [1]


Computer Ignition

Finally, the electronic system was replaced with a computer-based system. The sensor unit was essentially the same, but the mechanical/vacuum advance system was replaced by a software-controlled system running on a host computer. An example of this type of system is shown in the following diagram:


Figure 4 typical computer ignition system diagram [3]









[1] Datsun 200SX Owners Workshop Manual, Sparkford, Yeovil, Somerset,

England: J H Haynes and Peter G Strasman, 1979


[3] Toyota Van 1987 Repair Manual, Japan: Toyota Motor Corporation, 1987