Freelander Automatic Gearbox - JATCO: Driving Modes
AUTOMATIC GEARBOX - JATCO
44-44
DESCRIPTION AND OPERATION
Line Pressure Control
Line pressure refers to the operating fluid pressure that is supplied to the multi-plate clutches, multi-plate brakes and
brake band within the gearbox.
Line pressure control provides smooth vehicle operation and gear shift action. The line pressure control is
continuously responding to current driving conditions to regulate and deliver the optimum operating pressure at all
times. For example, line pressure is lower under normal operating conditions than it would be under hard acceleration.
The EAT ECU controls line pressure by actuating the line pressure solenoid valve in the valve block. The ECU
calculates the line pressure required by using engine speed, vehicle speed and throttle position.
High line pressures will cause very harsh gearshifts and gear engagement. Low line pressure will cause gearshifts to
take an excessive amount of time to change, which will quickly burn out the clutches, brakes and brake band within
the gearbox.
Driving Modes
There are five different driving modes that the driver can select:
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Normal mode
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Sport mode
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Manual (CommandShift) mode
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Hill Descent Control (HDC) mode
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Cruise mode.
Normal, sport, cruise and HDC modes are selected manually by the driver. Fast off and stop go modes are controlled
by the EAT ECU responding to driving conditions.
The different modes are selected by the gear selector lever or, in the case of cruise mode and HDC, a separate switch.
The gear change scheduling is altered to correspond with the mode selected.
Normal Mode
On power up the EAT ECU always initialises normal mode. In this mode all automatic/adaptive modes are active.
Normal mode uses gear shift and lock-up maps which allows vehicle operation which is a compromise between
performance, fuel consumption and emissions.
Sport Mode
In sport mode the EAT ECU controls the gearbox to downshift more readily and use gear change schedules that hold
the lower gears for longer at high engine speeds. This enhances acceleration and vehicle responsiveness. Sport
mode is selected by moving the gear selector lever to the 'S/M' position. 'Sport' is displayed in the instrument pack
LCD when this mode is selected.
Manual (CommandShift) Mode
Manual mode allows the driver to operate the gearbox as a semi-automatic, CommandShift gearbox. The driver can
change up and down the five gears with the freedom of a manual transmission.
Gearshift maps programmed in the EAT ECU protect the engine at high engine speeds by automatically changing up
to prevent engine over speed and changing down to prevent stalling.
Manual mode is entered by moving the selector lever to the 'S/M' position and then moving the lever to either the +
or - positions to move the gearbox up and down the five gear ratios. Manual mode is exited by moving the selector
back to position 'D'.
