Engine Cranking Signal
WARNING: This page is about a different car, the 1995 Toyota Land Cruiser. 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 STA terminal of Engine Control Module (ECM). The ECM uses input signal for controlling Pulsed Secondary Air Injection (PAIR) system (if equipped), fuel injection system, fuel pressure control system (if equipped), heated oxygen sensor system (if equipped), ignition timing (spark advance) and idle speed control system.