Engine Control Module: Description and Operation

PURPOSE/OPERATION
The powertrain control module controls the fuel injection system, ignition timing, and the idle speed control system. The powertrain control module also interrupts the operation of the air conditioning and EGR systems, and controls power to the fuel pump (through the control relay). The powertrain control module consists of a microprocessor, random access memory (RAM), read only memory (ROM), and an input/output interface. Based on information from the input sensors (engine coolant temperature, air flow, etc.), the powertrain control module determines optimum settings for the output actuators (injection, idle speed, ignition timing, etc.).

SELF-DIAGNOSIS
The powertrain control module constantly monitors input and output signals for correct operating range. If an irregularity occurs, the powertrain control module stores a trouble code which can be accessed via the self-diagnosis output terminal. The powertrain control module trouble code memory is maintained by direct battery Voltage so diagnostic results are held in memory even if the ignition key is turned off. The trouble codes will be erased if the battery terminal or the powertrain control unit connector is disconnected.