LR3/Disco 3
The pre-emptive strategy anticipates and predicts the locking torque value required for each differential to minimise slip
and maximise stability. Each Terrain Response program has a different threshold and input criteria for the pre-emptive
strategy. The pre-emptive strategy improves vehicle traction and composure by avoiding wheel spin. This is achieved by
anticipating the amount of differential lock required for the program selected. For example, a high locking torque would be
applied for rock crawl or slippery surfaces.
The reactive strategy varies the amount of locking torque in response to the actual slip level and the dynamic behaviour of
the vehicle. Each Terrain Response program has a different threshold and input for the reactive strategy. The reactive
strategy improves vehicle traction and composure by eliminating any wheel spin which has occurred after the pre-emptive
strategy was applied. The locking response applied is applicable to the terrain program selected, for example, very
sensitive on slippery surfaces to provide maximum traction and minimise surface damage.
The locking torque calculations use various signals from other subsystems, for example, engine torque, throttle position,
selected gear, steering angle, vehicle speed, lateral acceleration, yaw behaviour.
The Dynamic Stability Control function of the ABS system can override the Terrain Response differential control and
reduce any applied locking torque during DSC action. For additional information, refer to
Anti-Lock Control - Traction
Control
(206-09A Anti-Lock Control - Traction Control)
Air Suspension Control
The air suspension control module contains a strategy which provides automatic switching between normal and off-road
heights. Changes in vehicle height settings will be relayed to the driver via the instrument cluster message center and
LED illuminated icons on the switch. The automatic selection and deselection of the vehicle height provides automatic
increase and decrease in ground clearance and aims to provide maximum benefit to the selected terrain program.
On a vehicle fitted with a correctly installed, Land Rover approved trailer socket, if an electrical load is sensed on the
trailer socket, height changes are prohibited and the message center displays a message advising that a trailer is
connected and off-road height is not automatically selected. The driver can raise the suspension manually using the air
suspension switch.
NOTE:
ABS Control
The ABS module controls several vehicle functions and adjusts the operating parameters of these functions to optimise
the selected Terrain Response program.
Traction control uses different slip/acceleration thresholds to improve traction and vehicle composure. For example, the
system sensitivity is increased on slippery surfaces to reduce wheel spin.
If DSC is switched off (with the DSC switch on the instrument panel) when using a Terrain Response special program, if
the special program is subsequently changed for a different program DSC is automatically switched back on.
The stability control uses different threshold values for the selected program to automatically reduce DSC intervention,
removing the requirement for the driver to disable the DSC system in order to reduce engine intervention which is
sometimes induced in extreme off-road conditions. In extreme sand conditions, there may be an additional benefit of
disabling the DSC function using the DSC switch on the instrument panel in addition to selecting the sand program.
HDC is automatically switched on or off and target speeds are adjusted in response to the Terrain Response program
selected. The responsiveness of the HDC function is also increased where required.
Automatic operation of HDC aims to assist the driver by switching the system on or off when it is of most benefit. Target
speeds for HDC operation are also adjusted according the vehicle operating conditions.
Incorrect Program Usage
Selection of an inappropriate program is discouraged in the following ways:
The prohibiting of the automatic ride height selection is only operational if a Land Rover approved trailer socket is
fitted and an electrical load is sensed on the socket.
