DISTRIBUTORLESS Ignition System: Tercel
Distributorless Ignition System (DIS) uses the Engine Control Module (ECM) for determining ignition timing (spark advance). The ECM determines ignition timing (spark advance) based on various input signals, engine RPM and knock sensor input signal.
Conventional distributor and pick-up coil have been replaced by a camshaft and crankshaft position sensor. Camshaft position sensor and crankshaft position sensor deliver input signals to ECM. The ECM detects the standard crankshaft position based on camshaft position sensor input signals, and the actual crankshaft position and engine speed by the crankshaft position sensor input signals. Camshaft position sensor is located on end of cylinder head, just above the flywheel. See Figure-20. Crankshaft position sensor is located at timing belt end of engine, behind timing belt cover, near sprocket on crankshaft. See Figure-20.
The ECM uses 2 ignition primary control signals to the ignitor for the ignition coils. See Fig 1. The DIS uses 2 ignition coils which fire 2 cylinders simultaneously using the same ignition coil. See Fig 1. Cylinder No. 1 is at timing belt of engine and cylinder No. 4 is at flywheel end of engine. One ignition coil is mounted on top of spark plug on cylinder No. 3 with spark plug wire going to cylinder No. 2 spark plug. One ignition coil is mounted on top of spark plug on cylinder No. 4 with spark plug wire going to cylinder No. 1 spark plug. The ECM monitors IGF circuit at the ignitor to ensure ignition coils have fired.