Vehicle speed determining device having means for accurate determination of zeroing of vehicle speed

A controller for controlling an automatic transmission of a motor vehicle, including a vehicle speed determining device for determining a zeroed running speed of a vehicle, on the basis of pulses received from a vehicle speed sensor, comprising:

• first determining means for receiving pulses from said vehicle speed sensor and for making a first determination that said running speed of the vehicle has been zeroed when a predetermined first length of time has elasped after the reception of a last pulse from said vehicle speed sensor, without the reception of a next pulse;
• second determining means for making a second determination that a period of said next pulse is abnormally long when a predetermined second length of time longer than said predetermined first length of time has elapsed after the reception of said last pulse, without the reception of said next pulse;
• inhibiting means for inhibiting said first determining means for making said first determination that the running speed of the vehicle has been zeroed until said next means for making said first determination until said next pulse has been received when said second determining means has made said second determination;
• and
• means for outputting a signal to the transmission to shift the transmission as a function of said running speed determined by said first determining means.