Abnormality determining apparatus and method for automatic transmission

摘要

An ECU executes a program that includes a step of determining whether an output shaft rotation speed NOUT is equal to or greater than a reference rotation speed at which determining regions with all of the gear speeds in a stepped automatic transmission do not overlap, a step of determining that there is an abnormality in the gear speed by dividing the turbine rotation speed NT by the output shaft rotation speed NOUT if the output shaft rotation speed NOUT is not equal to or greater than that reference rotation speed, and a step of determining that there is an abnormality in the gear speed by subtracting a value, which is obtained by multiplying the output shaft rotation speed NOUT by the gear ratio, from the turbine rotation speed NT if the output shaft rotation speed NOUT is equal to or greater than that reference rotation speed.