Control apparatus and method of belt-type continuously variable transmission

The disclosure of Japanese Patent Application No. filed on May 23, 2000, including the specification, drawings and abstract, is incorporated herein by reference in its entirety. An apparatus and a method control a belt-type continuously variable transmission of a vehicle having a continuously variable speed ratio, which is a ratio of a rotation speed of an input shaft to a rotation speed of an output shaft. The speed ratio of the transmission is controlled by changing a groove width of each of the pulleys, and a belt clamping pressure applied to at least one of the pulleys to clamp the torque transfer belt also is controlled. Furthermore, the speed ratio of the transmission is set to a low-load speed ratio when it is determined that control of the belt clamping pressure has failed and the belt clamping pressure is raised to a high level. The low-load speed ratio is predetermined so that a load applied to the torque transfer belt is substantially minimized.