Abstract: A short between terminals of a linear solenoid controlled by an electronic control in an automatic transmission is detected by sensing when a PWM duty ratio set by a feedback control operating the linear solenoid is less than a reference duty ratio. The reference duty cycle is calculated to be between a range of expected normal duty ratios in the absence of the short and a range of expected short duty ratios in the presence of the short.

Abstract: A control system for an automatic transmission, including a frictional engagement element, an adjusted oil pressure producing mechanism for adjusting an oil pressure supplied from an oil pressure source to produce an adjusted oil pressure, a hydraulic servo for applying/releasing the frictional engagement element on the basis of the adjusted oil pressure, an engine load detecting mechanism, a vehicle speed detecting mechanism, an up-shift deciding mechanism for determining whether an up-shift has been executed, and a pressure regulate signal generating mechanism for calculating the regulated target pressure of the adjusted oil pressure, when the up-shift is executed, to output a pressure regulate signal. The adjusted pressure signal producing mechanism corrects the regulated target pressure on the basis of the difference between the present vehicle speed and the vehicle speed at a shift point when the shift is executed under the present engine load.