A vehicular transmission system is disclosed that includes a prime mover, a transmission having at least one mode of operation where the transmission is selectively shifted into a lower gear ratio as vehicle speed decreases, a master friction clutch for drivingly connecting the prime mover to the transmission, and at least one control unit. The control unit includes logic rules that selectively prohibit the transmission from being shifted into a lower gear ratio in response to a system operating condition during the at least one mode of operation. The system also includes at least one input corresponding to a system operating condition and at least one output corresponding to a command to prohibit the transmission from being shifted into a lower gear ratio in response to the sensed system operating condition. A control system and method for operating the vehicular transmission system are also disclosed.