Automotive Manual PDF

This article covers basic description and operation of engine performance-related systems and components. Read this article before diagnosing vehicles or systems with which you are not completely familiar.

COMPUTERIZED ENGINE CONTROLS TOYOTA COMPUTER CONTROL SYSTEM (TCCS)
The TCCS is a computerized emission, ignition and fuel injection control system. The TCCS lowers exhaust emissions while maintaining good fuel economy and driveability. System consists of various sensors, switches and control units. See Figs. 1 and 2. An Engine Control Module (ECM) controls the TCCS based on input signals received from various input devices. The ECM contains preprogrammed data to maintain optimum engine performance under all operating conditions.

ENGINE CONTROL MODULE
The Engine Control Module (ECM) microcomputer receives input signals from various sensors, switches, and ignition and starting system components. The ECM uses this information for controlling various functions. See OUTPUT SIGNALS under COMPUTERIZED ENGINE

CONTROLS.
The ECM has constant battery voltage at BATT terminal. The ECM contains a fail-safe function, used in case of sensor or switch failure. Fail-safe function uses preprogrammed values to provide a limp-in mode for minimal driveability. If a failure exists, ECM will inform the driver by turning on Malfunction Indicator Light (MIL) on the instrument panel.
NOTE: The MIL light may also be referred to as the CHECK ENGINE light.

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