Electronic Control Module (ECM)
If a system malfunction occurs, a back-up system within ECM controls fuel and ignition system functions according to preprogrammed values (limp-in mode). This allows vehicle to be driven, but performance may not be optimal.
A self-diagnostic function allows ECM to store Diagnostic Trouble Codes (DTCs) in its memory. If a system fault occurs, Malfunction Indicator Light (MIL) will illuminate to inform driver of system problems and the appropriate DTC will be stored in memory. For further self-diagnostic system information, see TESTS W/CODES article in this section.
NOTE:
Components are grouped into 2 categories. First category is INPUT DEVICES, which are components that control or produce signals monitored by ECM. Second category is OUTPUT SIGNALS, which are components controlled by ECM.