System Overview

NOTE: Electronic Control Module (ECM) may also be referred to as the Trionic control module or simply control module.

Trionic engine management system is used on all 4-Cyl. models. This system uses an Electronic Control Module (ECM) which is located behind a partition on the left side of the engine compartment. The ECM monitors engine and transmission operation and contains a self-diagnostic system which stores diagnostic trouble code(s). Many components incorporated in this system conform to the On-Board Diagnostics Generation II (OBD-II) standards. Federal law mandates this type of diagnostic system for all vehicles by 1996.

The goal of OBD-II regulation is to provide the vehicle with an on-board diagnostic system which is capable of continuously monitoring the efficiency of emissions control system, and to improve diagnosis and repair when system failures occur.

If any component or system malfunctions are detected by the ECM, the Malfunction Indicator Light (MIL) will display "CHECK ENGINE" on the instrument cluster and DTCs may be stored in the ECM memory. The MIL may also be referred to as the CHECK ENGINE light.

DTCs may be retrieved using a scan tool connected to Data Link Connector (DLC) or by initiating the MIL/DTC (flash Code) procedure. The scan tool can also be used to clear codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES (DTC) .