초록 ▼

A transmission diagnostic control effective when there is an apparent loss of the transmission output speed signal for determining if failure is real, and if so, the cause of the failure. When an apparent loss of the output signal is observed, the transmission is successively upshifted through its v

A transmission diagnostic control effective when there is an apparent loss of the transmission output speed signal for determining if failure is real, and if so, the cause of the failure. When an apparent loss of the output signal is observed, the transmission is successively upshifted through its various forward speed ratios while the transmission input speed is monitored to detect the occurrence of an upshift-related reduction thereof. If the shifting fails to produce a reduction in the transmission input speed by the time the transmission has been shifted to the highest available speed ratio, a total transmission failure is indicated. If the shifting produces a decrease in the transmission input speed, a total failure of the transmission is ruled out, and the diagnostic control determines if the failure is transmission or sensor related. If the output speed signal is still absent and the input speed is still high enough, after a shift-related reduction to generate vehicle motion, a speed sensor related failure is indicated. If the output speed signal indicates normal vehicle movement, the diagnostic control is terminated and all forward ratios lower than the current ratio are indicated as failed.

대표청구항 ▼

In a motor vehicle including an engine drivingly connected to an input shaft of a power transmission controllable to selectively establish one of a plurality of speed ratios between said input shaft and an output shaft thereof, where shifting among such speed ratios is scheduled in accordance with a

In a motor vehicle including an engine drivingly connected to an input shaft of a power transmission controllable to selectively establish one of a plurality of speed ratios between said input shaft and an output shaft thereof, where shifting among such speed ratios is scheduled in accordance with an output speed signal generated by a transmission output shaft speed sensor, a method of operation for diagnosing an apparent loss of the output speed signal, comprising the steps of: detecting the occurrence of an apparent failure condition in which the output speed signal indicates that the vehicle is at rest, but the transmission input shaft speed is substantially in excess of an idle speed of the engine; and in response to such detection; initiating upshifting of the transmission to successively higher speed ratios while monitoring the speed of the transmission input shaft to detect the occurrence of an upshift-related reduction thereof; and indicating the occurrence of (1) a total transmission speed ratio failure if no shift-related reduction of the transmission input shaft speed is detected by the time the transmission is upshifted to the highest available speed ratio, (2) a partial transmission speed ratio failure in response to the detection of a shift-related reduction of the transmission input shaft speed, if an output speed signal indicative of vehicle movement is observed, and (3) a speed sensor related failure in response to the detection of a shift-related reduction of the transmission input shaft speed, if the output speed signal indicates that the vehicle is at rest and the input shaft speed is sufficiently great to produce vehicle movement.