Powertrain Management: Description and Operation
DESCRIPTIONA control module is designed to maintain exhaust emissions levels at Federal and California emissions standards while providing good driveability and fuel efficiency, The functions of the system are based on data gathered by sensors and switches located throughout the vehicle. The control module maintains control over fuel delivery, ignition, idle air flow, the fuel pump and other system components, while monitoring the system for faulty operation with its diagnostic capabilities. This diagnostic capability is complemented by the diagnostic procedures contained in Computers and Control Systems. The control module language for communicating the source of the malfunction is a system of diagnostic trouble codes. When it finds a problem, it lights a Malfunction Indicator Lamp (MIL) "Service Engine Soon" on the instrument panel and a Diagnostic Trouble Code (DTC) will be stored in the control module memory. This does not mean that the engine should be stopped right away, but that the cause of the light coming "ON" should be checked as soon as reasonably possible.
It is important to review the system sections and control module wiring diagrams to determine what is controlled by the control module and what systems are non-control module controlled.