In the following run system the fail-safe device

摘要

PROBLEM TO BE SOLVED: To provide a fail-safe device in a follow-up traveling system for a vehicle, which can be realized at a low cost, certainly judges the lowering of the awakening degree of a driver due to follow-up traveling, especially, in a low speed range, and can take suitable action. SOLUTION: This fail-safe device is provided with a shift lever actuator 5 which forcibly operates a shift lever for changing over the traveling range of the automatic transmission of a vehicle, and a control circuit 10 which forcibly changes over to a first seed range or a second speed range by the shift lever actuator 5 in the case that a speed becomes less than a first set value (10 km/h), and restricts the speed not to increase without exceeding a second set value and also operates a warning device 6 by judging that the awakening degree of the driver is lowered in the case that the shift lever is not operated within a D range regardless of such a state that the speed should be increased by exceeding the second set value (20 km/h).