Abstract: Clutch operation signal issued in operational association with depression of a clutch pedal are taken as answer-back signals into an electronic control unit (ECU), a starter start command signal is issued in response to one of these answer-back signals. Additionally, a clutch upper switch and a clutch lower switch, which constitute a clutch sensor and are connected in series to each other, are inserted into a starter relay driving system, so that start due to mistaken operation and the like of ECU can be avoided.

Abstract: An engine of a motor vehicle is automatically stopped under predetermined conditions and automatically restarted under other predetermined conditions. The engine is restarted by a starter which is driven in response to an engine start signal. In automatically restarting the engine, the engine start signal is generated when restart conditions are fulfilled and a starter command is generated in a microcomputer. An operation of a clutch pedal is one of the restart conditions. The clutch pedal is provided therearound with a lower switch and an upper switch to detect an amount of a depression of the clutch pedal. The starter command is masked for a predetermined period of time starting from the time when the upper switch is turned OFF from the upper switch has been ON.

Abstract: In automatically stopping or restarting an engine on a basis of detecting an operational state of each component of a vehicle with the engine mounted thereon, judgement as to whether first condition of setting the function of allowing the engine to automatically stop and restart, second condition of automatically stopping the engine after the function is set and third condition of automatically restarting the engine after the function is set are fulfilled or not, respectively, is made by "and" of a plurality of signals including at least two or more signals out of a signal indicating an engine rotational speed, a signal indicating the generating condition of an alternator and a third signal indicating readiness or unreadiness for starting of the vehicle.

Abstract: An engine is automatically stopped under predetermined conditions, thereafter, automatically restarted under other predetermined conditions, and a primary check indicating device for indicating abnormal conditions in various components of a vehicle is forcedly turned OFF at least when the engine is automatically stopped. The primary check indicating device includes, for example, a charge warning lamp for indicating abnormality in the generating condition, an oil pressure lamp for indicating abnormality in the pressure of lubricating oil and an exhaust gas temperature lamp for indicating abnormality in the temperature of exhaust gas.

Abstract: In automatically stopping and restarting an engine on the basis of the operating conditions of various parts in a vehicle, the automatic engine stop and restart are effected by cutting off a fuel system, but not cutting off an iginition system. More specifically, a fuel control valve is provided in a path for feeding fuel to a slow port, and this control valve is closed on condition that at least the vehicle speed is in the state of zero and other conditions of allowing the automatic engine stop and restart are not met. An ignition signal taken from the energized ignition system is used to ensure that the engine is not started when it is already running.

Abstract: Determination as to whether the condition of automatically stopping an engine is formed or not is made based on outputs from pluralities of sensors and switches for detecting the operating conditions of various portions of a vehicle. Even if the result of determination satisfies the conditions of automatic stop, automatic stop is not effected when the temperature of the engine cooling water exceeds predetermined temperature limits.