Patent ID: 7004872

Claim:
A control method for an automatic transmission comprising: applying a hydraulic pressure of a working fluid to a plurality of frictional elements of the automatic transmission to control shifting of sears of the automatic transmission; varying a command value given to means for adjusting pressure of the working fluid; and determining whether gear shifting is permissive or not based on time variation of the hydraulic pressure applied to the frictional element that is adjusted by the pressure adjusting means according to the command value and detected by a means for detection of hydraulic pressure; wherein when the hydraulic pressure applied to the frictional element to be engaged in a target gear of the gears is defined as an engaging-side applied hydraulic pressure, and the command value for causing the pressure adjusting means to adjust the hydraulic pressure applied to the frictional element to be released in the target gear to a maximum pressure is defined as a complete engagement command value, the method further comprises: determining that gear shifting is prohibited if the engaging-side applied hydraulic pressure detected by the detecting means does not vary when the command value is varied; and providing the complete engagement command value to the pressure adjusting means.