The actual set parameters are monitored in an automatic transmission and compared with the expected, programmed values. The rate of change of the differences between the actual values and the programmed values are compared with threshold values to identify failures in the control system. The differences between the actual and programmed values are used to generate correction signals, if within preset ranges, and enable the transmission to be set for optimum performance. The failure signals are seen by the driver as optic and/or acoustic signals. The failure signals are also used to set the transmission into a basic control mode.