Abstract: A shift control method/system for shifting an automated compound range type transmission (14) in only the auxiliary section (96) to provide a limp-home function if system faults adversely effecting continued main section (94) shifting are detected is provided.

Abstract: An auxiliary transmission shift control system which combines the pressurized air supply lines for the range and splitter control switches mounted on the gear range selector lever in the vehicle cab and, therefore, eliminates one pressurized supply line. The interlock function (preventing shifting the splitter ON while in LOW range) is accomplished by preventing depressurization of the OFF side of the splitter cylinder if the range cylinder is in LOW position. Depressurization is prevented by pressurizing the OFF side of the splitter cylinder via a passageway connecting with the LOW side of the range cylinder.

Abstract: An improved control system and method for an automatic/semi-automatic transmission system (10) including an automatic change gear transmission (12) driven by a throttle (26) controlled engine (14) is provided. The control system includes a processing unit (42) for receiving inputs indicating at least throttle position (THL) and vehicle speed (OS) and for determining vehicle deceleration (dOS/dt) and for processing these inputs in accordance with a program or logic rules to determine the selected engaged gear ratio and for issuing command signals to a transmission shifting mechanism (34). The processing unit includes logic rules by which vehicle performance is maximized and the control will evaluate and allow and/or execute skip downshifts upon sensing conditions indicative of vehicle deceleration due to ascending a steep grade.