Patent ID: 6732038
Filing Date: 2004-05-04
Classification: F16H

Abstract:
A method of operation for a motor vehicle powertrain including an engine driving two or more vehicle wheels through an automatic shift transmission that provides a reverse gear and two or more forward gears, where the reverse gear is engaged when a range selector is positioned to select reverse movement of the vehicle and one of the forward gears is engaged when the range selector is positioned to select forward movement of the vehicle, the method comprising the steps of:selecting a desired forward gear to engage based on an engine load parameter and an indication of vehicle speed; detecting an engagement of the reverse gear; if the reverse gear has not been engaged for a calibrated interval of time, determining said indication of vehicle speed based on an output speed of said transmission; if the reverse gear has been engaged within said calibrated interval of time, and less than all of the vehicle wheels are being driven through the transmission, measuring a speed of one or more un-driven wheels and determining said indication of vehicle speed based on such un-driven wheel speed; and if the reverse gear has been engaged within said calibrated interval of time, and all of the vehicle wheels are being driven through the transmission, measuring a speed of each driven wheel, and determining said indication of vehicle speed based on such driven wheel speeds.