The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 21, 2001
Filed:
May. 22, 2000
Christopher Ray Fox, Martinsville, IN (US);
Scott E Mundy, Indianapolis, IN (US);
Sean E Gleason, Indianapolis, IN (US);
Jeffrey Kurt Runde, Fishers, IN (US);
General Motors Corporation, Detroit, MI (US);
Abstract
An improved diagnostic control method for a motor vehicle powertrain including an electronically controlled multi-range transmission and a multi-range transfer case, wherein a default determination of transfer case range enables reliable evaluation of transmission ratio, for powertrain configurations with or without a transfer case range indicator switch. An overall speed ratio is computed according to a ratio of the transmission input speed and the transfer case output speed, and the computed ratio is monitored to identify a period of stable operation at the conclusion of transmission shifting and in steady state operation during which the rate of change of the computed ratio is stable over a predefined interval. If the computed ratio is also deemed to be stable, it is compared with an expected overall ratio based on an assumed speed range (low or high) of the transfer case. In configurations having a transfer case indicator switch, the switch state determines the assumed speed range, whereas in configurations not having an indicator switch, a low range of the transfer case is assumed. A default condition of the transfer case is determined based on the ratio comparison, and transmission diagnosis is carried out based on the default conditions.