| 摘要 |
PURPOSE: A deciding method of defects in a speed sensor is provided to devise the safe driving by preventing a unexpected down shift, to reduce the production cost and to improve the productivity by eliminating the speed sensor. CONSTITUTION: A drive range of a shift lever is detected. In the drive range, the shifting of a shift gear is checked(S110). A speed reduction ratio is compared with a limited reduction ratio when the shifting is not operated(S120). In raising the speed reduction ratio over the limited reduction ratio, the satisfaction of a set shift prohibition condition is checked. Otherwise, a driving speed reduction ratio is compared with a limit reference speed reduction ratio. In reducing the driving speed reduction ratio over the limit reference speed reduction ratio by a braking, the satisfaction of the set shift prohibition condition is checked. Otherwise, a speed is detected and an RPM(Rotation Per Minute) of an engine is compared with an RPM of a stall by deciding as the braking operation is not performed. In increasing the RPM of the engine over the RPM of the stall, a shift prohibition signal is outputted by deciding as a speed detector is short. Otherwise, a shifting to a target shift gear is performed. Thereby, the production cost is reduced and the assembling productivity is increased.
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