Start (Cranking) Signal

The start (cranking) signal from starter relay signals engine controller when starter is engaged. When engine controller determines that starter is engaged, it starts looking at inputs from crankshaft position sensor and synchronization signal generator.

The engine controller then uses these signals to determine spark timing and whether the first fuel injection should occur at cylinder No. 4 or 1 (4-cylinder) or cylinder No. 3 or 4 (6-cylinder). Once synchronization has been established, the engine controller energizes the proper injector and provides the ignition output needed to start the engine.