Engine Control Module (ECM)
The ECM monitors and controls vehicle emissions, fuel system and ignition system by using input signals for various input devices. The ECM processes signals from input devices and delivers output signals to various components for controlling system operation to achieve optimum engine performance for all operating conditions. See INPUT DEVICES and OUTPUT DEVICES under COMPUTERIZED ENGINE CONTROLS. ECM contains a self-diagnostic system which stores a Diagnostic Trouble Code (DTC) if an electronic control system failure exists. DTC may be retrieved from ECM for system diagnosis by using a scan tool. See SELF-DIAGNOSTIC SYSTEM. The ECM is located below instrument panel, in front of center console. See Fig 1 .
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Components are grouped into 2 categories. The first category covers INPUT DEVICES, which control or produce voltage signals monitored by the ECM. The second category covers OUTPUT SIGNALS, which are components controlled by the ECM.