Ignition Coil: Description and Operation
Ignition coils
The electronic ignition system uses four double ended coils. They are mounted on a bracket fitted to the rear of the engine. The circuit to each coil is completed by switching within the ECM, allowing each coil to charge up and fire. Sparks are produced in two cylinders simultaneously, one on compression stroke, the other on exhaust stroke. Note that coil 1 feeds cylinders 1 and 6, coil 2 feeds cylinders 5 and 8, coil 3 feeds cylinders 4 and 7, and coil 4 feeds cylinders 2 and 3. Due to the ease of combustion in the cylinder on the compression stroke, more energy is dissipated in that cylinder. Coil failure will result in a lack of sparks and misfire in the affected cylinders. The fault is indicated by illumination of the malfunction indicator light (MIL) on North American specification vehicles.