Components Description

COMPONENT DESCRIPTIONS

Transmission Unit
The ZF 4HP 24 E automatic transmission unit houses the three solenoid valves which control gear shifts. A pressure control valve is also located on the solenoid valve block. These four valves initiate and control shift patterns within the transmission unit by regulating fluid flow.

Rotary Selector Switch
The seven position rotary gear selector switch is mounted on the LH side of the transmission unit and indicates gear selection to the Transmission Control Module (TCM) and decoder module.

Transmission Control Module
The electronic transmission control module regulates gear changes by controlling the operation of the transmission unit solenoid valves, and monitoring the state of other vehicle systems which have an effect on torque demand, vehicle speed etc. The module also interfaces with the engine management system, climate control system, body processor unit and ABS/traction control system.

Decoder Module
The decoder module mounted by the side of the selector mechanism "J" gate interfaces the gear selector switch and selector illuminated module, to give visual indication of gear selection.

Performance Mode Switch
The two position performance mode switch allows selection of SPORT or NORMAL mode as required by the driver. The switch input to TCM causes a gear shift pattern change so that changes take place at higher engine revs, enhancing performance, when in SPORT mode. For everyday use, NORMAL mode utilizes a shift pattern for optimum driver comfort.

Kick-down Switch
The KICK-DOWN facility is activated when full downward travel of the accelerator pedal occurs. Activation of the switch provides a signal to TCM indicating that greater acceleration, and hence a downward gear shift, is required. Switch height is adjustable so that KICK-DOWN can be achieved at a predetermined throttle opening.

Gear Selection Illumination Module
This module is located above the gear selector mechanism and its sole purpose is to display the selected gear (in red) on receipt of a signal from the decoder module.