Valve Body: Description and Operation

Transmission Control Unit - (Valve Body)

The electronic-hydraulic control unit comprising a series of valve blocks housing a cable-operated manual valve, control pistons and pressure valves is attached to the underside of the transmission housing; the unit controls the operation of the gear train clutches and directs oil pressure to the appropriate system components refer to the transmission description in it's entirety to understand the operation of the transmission.

The four valve blocks in which the control valves, pistons etc are located, are mounted and connected through a main gallery plate. The three solenoid valves MV1, MV2 and MV3 and the pressure regulator operating solenoid are located on the upper surface of the plate; electrical connections between the solenoids and the transmission and transmission control unit are via cable harnesses (refer to relevant diagrams and tables for details of the various pin connections).

Operation of the transmission control unit is through an electronic Transmission Control Module (TCM) which on receipt of electrical signals from transmission and engine management sources, activates the hydraulic pressure regulating and shift valves via the solenoid valves located on the valve block.

The gear selector in the vehicle transmits movement, via the selector cable, to the selector lever on the side of the gearbox; this rotates the selector shaft which controls the manual selector valve. The rotary position of the shaft is monitored by the rotary switch.