Ignition Coil: Description and Operation

Ignition Coil Packs

The ignition coil packs contain two separate ignition coils which are controlled by the EDIS module through two coil leads. Each ignition coil fires two spark plugs simultaneously; one plug on the compression stroke and one on the exhaust stroke. The spark plug fired on the exhaust stroke uses very little of the ignition coil's stored energy. The majority of the energy is used by the spark plug on the compression stroke. Since these two spark plugs are connected in series, the firing voltage of one plug will be negative with respect to ground, while the voltage of the other will be positive with respect to ground.

The right coil pack is mounted on the engine drive belt tensioner assembly. The left coil pack is mounted on the A/C idler pulley assembly. There are two cylinder numbers on each coil terminal to allow the coil packs to be interchangeable.