Engine Cranking Signal
WARNING: This page is about a different car, the 1996 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.
While engine is cranking and voltage is applied to the starter an input signal is also delivered to NSW terminal of Engine Control Module (ECM). The ECM may use input signal for controlling, fuel injection system, fuel pressure control system (if equipped), heated oxygen sensor system (if equipped), ignition timing (spark advance) and idle speed control system.