Patent ID: 7670254

Claim:
Method to identify a fault in a hydraulic circuit of a torque transmission device selectively operative in one of a plurality of operating modes comprising fixed gear modes and two continuously variable modes through selective actuation of a plurality of torque-transfer clutches, the method comprising: controlling a plurality of flow control devices of the hydraulic circuit; monitoring a plurality of pressure monitoring devices in the hydraulic circuit; and, identifying a fault in the hydraulic circuit when a monitored signal output from any one of the pressure monitoring devices does not correspond to an expected signal output for the pressure monitoring device after an elapsed time period comprising isolating the fault, comprising selectively deactivating one of the flow control devices, monitoring slippage of an off-going clutch, identifying a fault related to the selectively deactivated flow control device when the slippage of the off-going clutch does not exceed a minimum threshold, and identifying a fault related to the pressure monitoring device when the slippage of the off-going clutch exceeds the minimum threshold.