A number N of position sensors, each associated with one of N shift rails in a shift rail transmission system, wherein the set of N sensors is divided into subsets and each subset is provided a common reference from a control module; and a processing component that determines from data from each sensor whether the shift rail associated with that sensor is in a position of engagement of a first gear, a position of engagement of a second gear, or in a neutral position.Further, providing a first common reference to a first set of shift rail position sensors; providing a second common reference to a second set of shift rail position sensors; receiving sensor data from each position sensor; determining that the data from the first set of position sensors is unreliable; and operating a transmission using only the gears related to the position sensors in the second set.