Honda Giken Kogyo K.k.

Mitsuba Electric Mfg. Co., Ltd.

Kazuhiko Tachikawa

Masahiko Asakura

Norimitsu Kurihara

Mitsuru Matsui

Yasuhiko Otsuka

A vehicle cruise control system, comprising a control circuit for producing a control signal for maintaining a speed of a vehicle at a fixed level according to a difference between an actual vehicle speed and a target vehicle speed, and a drive circuit for producing a drive signal for selectively driving an actuator in a direction either to accelerate the vehicle or to decelerate the vehicle according to the control signal from the control circuit. The drive circuit is provided with a transistor bridge circuit comprising four drive transistors for producing the drive signal. The control circuit is provided with a detection means for detecting an abnormal state of the system and an inhibiting means which brings at least one of the drive transistors into an non-conductive state when any abnormal state is detected by the detecting means. The control circuit may be programmed to perform a certain diagnostic procedure for testing the soundness of the drive transistors. Thus, erratic behavior of the cruise control system and destruction of the drive transistors can be effectively prevented.

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Kiryu, Japan

Kazuhiko Tachikawa