Except ESA

As distributor shaft turns reluctor, reluctor teeth (one for each engine cylinder) pass magnetic pick-up coil assembly. See Fig 1.

As air gap changes with approach and pass of each reluctor tooth, magnetic field varies. This creates a signal in pick-up coil assembly.

Ignitor senses this signal, and turns ignition coil primary circuit on and off. This causes magnetic field in coil primary circuit to build and collapse, resulting in a voltage surge in secondary, which fires the spark plugs.

Fig 1: Schematic of Nippondenso Electronic Ignition Circuit Some models have EFI relays or other minor variations.

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Fig 2: Schematic of Toyota ESA Ignition System Circuit Ignition spark advance is computer controlled.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002