Powertrain Management: Description and Operation

Electronic Concentrated Control System Operation:

System Chart:

PURPOSE
The Electronic Concentrated Engine Control System (ECCS) consists of an Electronic Control Module (ECM) or central processor, several sensors or input devices and actuators or output devices. All components and circuits must work in conjunction with each other for the system to control emissions and maintain fuel economy and performance at optimum levels.

Self-Diagnostics
The ECM monitors several circuit and components to determine if they are functioning properly. If a malfunction is detected in certain circuits the "MALFUNCTION INDICATOR LAMP" (MIL) illuminates to alert the driver that a problem is occuring. The lamp remains illuminated as long the fault is present.

The ECM stores a code in its memory to aid the technician in diagnosis. If the lamp turns off, the fault is no longer present, but the code is stored for 50 attempted engine starts or until the code is cleared from the memory. This aids in diagnosing intermittant problems.

Fail-Safe (Back-Up) Operation
The ECM substitutes an input signal in the event of a failure in the ECM's Central Processing Unit (CPU), mass air flow meter, engine temperature sensor or throttle sensor circuits. The engine operates at reduced capacity to allow the vehicle to be driven until repairs can be made. The "MALFUNCTION INDICATOR LAMP" blinks when the ECCS system is in the fail-safe mode.