A Pressure Switch Manifold for Electronically Controlled Transmissions

The electronically controlled transmission has evolved to improve vehicle driveability, shift quality and fuel efficiency. The transmission's computer relies on sensing and modulating fluid pressure for diagnostic and control functions. A Pressure Switch Manifold (PSM) has been developed to sense the pressures in selected hydraulic circuits, providing the computer with PRNDL position and clutch fill information. The device consists of multiple compact snap acting pressure switches electrically interconnected on asingle assembly. The manifold mountsdirectly to the valvebody, with the switches coupled to the appropriate fluid channels. In applications where the PSM is submerged in oil, a thermistor is designed in to provide for temperature sensing. This paper describes the design, performance and application of the pressure switch manifold.