Gm Global Technolgoy Operations, Inc.

Jay Ho

David William Minner

A method of controlling an automatic transmission connected to an engine in a motor vehicle employs a switch for requesting selection of transmission speed-ratio ranges. According to the method, the switch receives an input signal and generates an output signal having the same duration as the input signal. A controller programmed with an engine threshold speed and a threshold signal duration receives and compares the output signal with the threshold signal duration. The controller also determines a current transmission speed-ratio range and a transmission threshold speed-ratio range that is defined by engine's threshold speed. The controller additionally commands the transmission to change the current speed-ratio range to a neighboring speed-ratio range if the signal duration is less than or equal to the threshold. Furthermore, the controller commands the transmission to change the current speed-ratio range to the threshold speed-ratio range if the signal duration is greater than the threshold.

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Novi, MI, United States of America

Jay Ho