Abstract: The data holding device includes a switch adapted to be turned on and off in accordance with a state of the engine, a control element in the form of a CPU for determining the presence or absence of abnormality in the engine based on a state of the switch, a data storage element in the form of an EEPROM for storing recognized data corresponding to the presence or absence of abnormality, an external power supply for supplying a power supply voltage to the CPU, and a voltage holding circuit for holding the power supply voltage at a prescribed value. When abnormality is found in the engine, plural pieces of recognized data indicative of abnormality are stored into the EEPROM, and the engine state is determined based on groups of recognized data stored in the EEPROM.

Abstract: An engine control apparatus with a mode changeover function for transition to a fault diagnosis mode and fault decision display without using dedicated fault diagnosis input/output unit includes plural input terminals connected to plural input units (2, 3, 4), respectively, and plural output terminals connected to plural corresponding display devices (7, 8, 9), respectively. The apparatus is designed to fetch input information from the input units (2, 3, 4) to thereby drive the display devices (7, 8, 9) and change over control modes in response to external input information. A removable short-circuit line (10) is provided for forming a short-circuit selectively between a predetermined one of the plural output terminals and a predetermined one of the plural input terminals. A mode changeover decision unit decides the control mode changeover when the short-circuit is formed.

Abstract: The data holding device includes a switch adapted to be turned on and off in accordance with a state of the engine, a control element in the form of a CPU for determining the presence or absence of abnormality in the engine based on a state of the switch, a data storage element in the form of an EEPROM for storing recognized data corresponding to the presence or absence of abnormality, an external power supply for supplying a power supply voltage to the CPU, and a voltage holding circuit for holding the power supply voltage at a prescribed value. When abnormality is found in the engine, plural pieces of recognized data indicative of abnormality are stored into the EEPROM, and the engine state is determined based on groups of recognized data stored in the EEPROM.

Abstract: An engine control apparatus with a mode changeover function for transition to a fault diagnosis mode and fault decision display without using dedicated fault diagnosis input/output unit includes plural input terminals connected to plural input units (2, 3, 4), respectively, and plural output terminals connected to plural corresponding display devices (7, 8, 9), respectively. The apparatus is designed to fetch input information from the input units (2, 3, 4) to thereby drive the display devices (7, 8, 9) and change over control modes in response to external input information. A removable short-circuit line (10) is provided for forming a short-circuit selectively between a predetermined one of the plural output terminals and a predetermined one of the plural input terminals. A mode changeover decision means decides the control mode changeover when the short-circuit is formed.