LR3/Disco 3
when the ignition switch is in ignition position II, a ground and high speed CAN positive and negative.
TERRAIN RESPONSE OPERATION
The following vehicle subsystem control modules are used for the Terrain Response system:
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Engine management (engine control module)
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Transmission control (transmission control module - automatic transmission only)
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Transfer box control (transfer box control module)
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Rear differential control (rear differential control module - if fitted)
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Air suspension control (air suspension control module)
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Brake system (ABS/DSC/ETC/HDC functions) (ABS module)
Each subsystem operates in different ways in relation to the selected Terrain Response program to achieve the optimum
traction, stability and ease of control for the terrain encountered. The system has a safety factor built in which ensures
that any program can be safely used on any surface, even when an inappropriate program selection has been made.
Engine Management System (EMS)
The EMS varies the throttle pedal response to control the engine torque output. The EMS can change the throttle maps to
change the amount of torque per percentage of pedal travel. The EMS can also change the throttle response to control
the allowed torque change relative to the percentage pedal travel.
Each terrain program uses a combination of operating parameters for each subsystem. Changing between terrain
programs initiates a different set of operating characteristics which will be noticeable to the driver. The driver will notice
differences in engine and throttle response when, for example, the throttle pedal is held in a constant position and the
terrain program is changed from grass/gravel/snow to sand, the driver will notice the torque and engine speed increase. If
the terrain program is changed from sand to grass/gravel/snow the driver will notice a reduction in torque and engine
speed.
NOTE:
Transmission Control
The transmission control module changes the shift maps for the Terrain Response program selected. This changes the
shift points providing early or late upshifts and downshifts.
On slippery surfaces the transmission will select 2nd gear in high range or 3rd gear in low range for starting from a
standstill to minimise wheel slip. In muddy conditions the transmission will provide maximum torque output from the
transmission. In sand the transmission will provide an output which passes maximum engine power from the
transmission.
In rock crawl special program (low range) the transmission will select 1st gear for driving off.
Sport mode is only available when the general program is selected and the transfer box is in high range. Sport mode is
disabled in low range and all Terrain Response special programs. CommandShift™ is available in any program and also
in high or low range.
If the transmission is in 'Sport' mode and a special program is subsequently selected, the transmission will automatically
change to manual 'CommandShift™' mode. If a special program is already selected and the transmission selector lever is
moved from drive 'D' to the 'Sport' mode position, the transmission will automatically change to 'CommandShift™' mode.
Transfer Box and Rear Differential Control
The transfer box electronically controlled differential and the rear electronically controlled differential (if fitted) are treated
as one system. The electronic rear differential is an optional fitment on vehicles fitted with the Terrain Response system.
The differential control has two operating strategies; pre-emptive and reactive.
The change in torque and engine speed can take approximately 30 seconds and care must be taken not to confuse
the Terrain Response system operation with an EMS fault.
