Ride and Handling Optimization Land Rover Range Rover L322

Scheme 72

INTRODUCTION

The Terrain Response™ system allows the driver to select a program which aims to provide the optimum settings for traction and performance for the prevailing terrain conditions. The system cannot be switched off. The 'special programs off' is the default program and covers all general driving conditions. Four specific terrain programs are selectable to cover all terrain surfaces.

The system is controlled by the rotary control located on the floor console, rearward of the transmission selector lever. The rotary control allows the selection of one of the following five programs

1. Special programs off
2. Grass/Gravel/Snow
3. Mud/Ruts
4. Sand
5. Rock crawl.

The rotary-control type selector can be rotated through 360 degrees or more in either direction to select each program in turn. The instrument cluster will display the selected program in the message center.

The Terrain Response system uses a combination of a number of vehicle subsystems to achieve the required vehicle characteristics for the terrain selected. The following subsystems make up the Terrain Response system

1. Engine management system
2. Automatic transmission
3. Transfer box (center differential)
4. Rear differential (electronically controlled)
5. Brake system (DSC/ETC/HDC functions)
6. Air suspension.

A Terrain Response control module is located, depending on specification, below the rotary control. The control module detects the program selection made and transmits a signal on the high speed controller area network (CAN) bus which is received by each of the subsystem control modules.

Each of the affected sub-system control modules contain software which applies the correct operating parameters to their controlled system for the Terrain Response program selection made.

They also provide feedback for the selected program so that the Terrain Response control module can check that all systems have changed to the correct operating parameters.

Information is displayed in the instrument cluster message center which informs the driver of improvements which can be made to the vehicle operating parameters to optimize the vehicle for the prevailing conditions. Inexperienced off-road drivers may benefit from the automatic assistance of the Terrain Response system and the driver information. Experienced off-road drivers can select the specific programs for extreme conditions to access control over the vehicle systems for example, accelerator pedal progressions, transmission shift maps, accelerator pedal maps or traction settings, which are not accessible on vehicles without Terrain Response.

Terrain Response Controls

Terrain Response selection is via a rotary control. There are five Terrain Response programs marked around the control.

Each program is denoted by a symbol which represents the terrain encountered.

Information relating to the suitability of each selected program on different types of surface, is given on the touch screen, via the '4 x 4 Info' soft key. The displayed text is relevant to the currently selected program.

The Terrain Response control module is located below the Terrain Response rotary control. The module is connected via a harness connector which also contains the wiring for the: Hill Descent Control (HDC) switch, transfer box high/low range switch, air suspension control switch and the switch illumination circuits.

Scheme 73

PRINCIPLES OF OPERATION

The following vehicle subsystem control modules are used for the Terrain Response system

1. Engine management (engine control module (ECM))
2. Transmission control (transmission control module (TCM))
3. Transfer box control (transfer box and center differential control module)
4. Rear differential control (rear differential control module - if fitted)
5. Air suspension control (air suspension control module)
6. Brake system (DSC/ETC/HDC functions) (anti-lock brake system (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 accelerator pedal response to control the engine torque output. The EMS can change the accelerator pedal maps to change the amount of torque per percentage of pedal travel. The EMS can also change the accelerator 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 accelerator response when, for example, the accelerator 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. 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.

Transmission Control

The transmission control module (TCM) 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 minimize 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 only) 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 when any Terrain Response special program is selected. 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 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 pre-emptive strategy anticipates and predicts the locking torque value required for each differential to minimize slip and maximize 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 behavior 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 torque applied is applicable to the terrain program selected, for example, very sensitive on slippery surfaces to provide maximum traction and minimize surface damage.

The Dynamic Stability Control (DSC) function of the anti-lock brake system (ABS) can override the Terrain Response differential control and reduce any applied locking torque during DSC action.

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 light emitting diode (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. 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.

Brake System Control

The anti-lock brake system (ABS) module controls several vehicle functions and adjusts the operating parameters of these functions to optimize 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

1. The active program icon is continually displayed in the instrument cluster message center
2. The Terrain Response control module 'locks' out certain functions in some programs, e.g., speed control is only available with the special programs off or grass/gravel/snow program transmission 'Sport' mode is deactivated in all special programs.
3. In any special program, except the grass/gravel/snow program, when the ignition has been in the off position, continually for more than six hours, the Terrain Response system defaults to the Special Programs off. When in the grass/gravel/snow program, the Terrain Response system will never default to the Special Programs off. This is to allow for drivers in cold climates where continuous use of the grass/gravel/snow program would be beneficial.
4. The rock crawl program is only available with the transfer box in low range.

Selection of an inappropriate program for the terrain conditions will not endanger the driver or cause immediate damage to the vehicle. Although, continued use of an inappropriate program may reduce the life of some components. The driver may notice reduced vehicle response, with the engine and transmission being less responsive than in the special programs off. Also, in some programs, HDC will remain on, signified by illumination of the HDC indicator in the instrument cluster. The driver may also notice torque 'wind-up' in the center and rear differentials causing a 'braking' effect when the vehicle is maneuvered in some special programs.

The use of the special programs in the Terrain Response system is monitored by the Terrain Response control module which records the mileage and time the vehicle has operated in a specific program in high and low range. This information can be retrieved using an approved Land Rover diagnostic system and used by the dealer technician to check customer concerns, e.g. high fuel consumption which may be due to continued use of a certain program.

Driver Information

The instrument cluster contains a message center which displays vehicle information to the driver. The message center contains the Terrain Response program icons which display the currently selected program. If no symbol is displayed, no special program is selected and the system is in special programs off.

Any required changes to the subsystems are also passed to the driver in the form of indicator illumination in the instrument cluster or appropriate messages in the message center, HDC off or air suspension height change for example.

In certain operating conditions, the Terrain Response system also displays advice or warning messages to ensure the driver is using the vehicle to its full potential, e.g.

1. Steering angle is displayed in the message center to avoid driving in deep ruts with steering lock applied
2. gear information is displayed to recommend a gear for slippery conditions
3. if the system automatically provided off road ride height, but the driver subsequently lowers the vehicle to normal height, then the system may advise that this will cause a risk of grounding.

The messages which can be displayed in the instrument cluster message center are detailed in the Information and Message Center instructions. For additional information, see appropriate Information and Message Center instructions.

DIAGNOSTICS

The Terrain Response control module stores information on detected Terrain Response faults and controller area network (CAN) errors which can be interrogated using an approved Land Rover diagnostic system. The Terrain Response sub-systems and the instrument cluster also store fault information relating to controller area network (CAN) errors from the Terrain Response control module.

The control module also stores the miles traveled and time elapsed in high range for the individual programs and in low range for use of all programs which can also be retrieved using an Land Rover approved diagnostic system. This information aids diagnosis of the Terrain Response system and also provides an indication of Terrain Response system abuse by the driver which can lead to premature component failure.

Terrain Response System Fault Diagnosis

Terrain Response relies on the correct functionality of the five sub-systems. If one of the sub-systems develops a fault, the Terrain Response system will not function, even though the fault is NOT in the Terrain Response system. The Terrain Response control module and rotary control should only be investigated if there are no apparent faults in any of the sub-systems. If a fault in a sub-system is subsequently corrected, the Terrain Response system will function normally after an ignition on and off cycle.

Terrain Response Sub-System Faults

If a fault occurs in a sub-system, the driver is alerted by the illumination of a warning indicator and/or an appropriate message for that sub-system in the instrument cluster message center. There will be no warning of a Terrain Response system fault.

When a sub-system fault is present and the driver attempts to select a different Terrain Response program using the rotary control or at the next ignition on cycle, a message 'SYSTEM FAULT SPECIAL PROGRAMS NOT AVAILABLE' will appear in the message center. This implies that the Terrain Response system has a fault, but only because a sub-system fault is preventing its operation. This message will be displayed for 5 seconds per ignition cycle, but is repeated if a further selection is made by the driver using the Terrain Response rotary control or at the next ignition on cycle.

Note. The message 'SYSTEM FAULT SPECIAL PROGRAMS NOT AVAILABLE' can also be generated by a fault in the Terrain Response rotary control or control module. See the appropriate instructions for details of rotary control or control module faults.

It is not possible for the Terrain Response control module to cause any fault behavior (warning indicator illumination or message generation) in any of the five sub-systems. Illumination of a sub-system warning indicator and/or a sub-system related message will never be associated with a Terrain Response control module or Terrain Response system fault.

The sub-system control modules can detect a fault with the controller area network (CAN) bus signal from the Terrain Response control module. If a fault in the Terrain Response system is detected, the sub-system control modules will operate in the 'special programs off' setting. The sub-system control modules will record a fault code for a failure of the Terrain Response controller area network (CAN) bus signal. These faults can be retrieved using an approved Land Rover diagnostic system and will provide useful information to indicate investigation of the Terrain Response control module or the controller area network (CAN) bus network.

Terrain Response Rotary Control or Control Module Fault

If a fault occurs in the Terrain Response rotary control, all control icon amber light emitting diode (LED)'s will be turned off (background illumination will remain on) and selection of the control is ignored. The instrument cluster message center will display a message 'SYSTEM FAULT SPECIAL PROGRAMS NOT AVAILABLE' when the fault occurs, if the fault is present and the driver attempts to select a special program (if the control module is able to do this) or at the next ignition on cycle.

If a failure of a control icon amber light emitting diode (LED) occurs, the Terrain Response system will still function. Any selected special program will default to 'special programs off' at every ignition on cycle, with the exception of the grass/gravel/snow program.

The Terrain Response rotary control and the control module are an integral unit. If a fault occurs in either component, the whole unit will require replacement. BEFORE REPLACING THE TERRAIN RESPONSE CONTROL MODULE, ENSURE THAT THE FAULT IS NOT IN ANY OF THE SUB-SYSTEM MODULES.

CAN Bus Faults

If a controller area network (CAN) bus fault exists and prevents Terrain Response system operation, all of the Terrain Response control icon light emitting diode (LED)'s will be illuminated and the control selection ignored.

If the instrument cluster does not receive a Terrain Response system controller area network (CAN) bus message from the Terrain Response Control module, the message 'SYSTEM FAULT SPECIAL PROGRAMS NOT AVAILABLE' will be displayed when the fault occurs and will be repeated at every ignition on cycle.

User Error

The following incorrect usage of the system may be misinterpreted as a system fault

1. Engine not running - Program changes and driver advisory messages are only available with the engine running
2. Rock crawl program selected but transfer box in high range
3. Special program change attempted with DSC or anti-lock brake system (ABS) active (this includes anti-lock brake system (ABS) cycling which is operational when HDC is being used on slippery or loose surfaces).
4. Special program change attempted with overheat condition present on center or rear differential.

Ride and handling optimization incorporates the adaptive damping system and also the terrain response system which links a number of modules around the vehicle to give the best combination of settings in the different systems.

For information on the description and operation of the system, refer to the relevant Description and Operation instructions of the workshop information.

INSPECTION AND VERIFICATION

1. Verify the customer concern.
2. Visually inspect for obvious mechanical or electrical faults. VISUAL INSPECTION Mechanical Electrical Tire condition, pressures, etc. Driveline components (correct installation, damage, etc.) Engine components (correct installation, damage, etc.) Transmission components (correct installation, damage, etc.) Suspension components (correct installation, damage, etc.) Fuses Harnesses/Connectors Terrain Response Control Module (ATCM) Engine Control Module (ECM) Transmission Control Module (TCM) Transfer Case Control Module (TCCM) ABS Control Module Rear Differential Control Module (RDCM) Air Suspension Control Module (SUMB) Controller Area Network (CAN) circuits
3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
4. Use the approved diagnostic system or a scan tool to retrieve any diagnostic trouble codes (DTCs) before moving onto the symptom chart or DTC index. Make sure that all DTCs are cleared following rectification.

SYMPTOM CHART

Because the overall function of the system is dependent on sub-systems, it is possible to misinterpret displays in the message center as being terrain response faults when they are actually a result of a fault in one of the sub-systems.

Refer to the table below for help in deciding when to investigate terrain response faults and when the fault is likely to be in a sub-system.

DTC INDEX

For a list of Diagnostic Trouble Codes (DTCs) that could be logged on this vehicle, please refer to appropriate instructions.

Scheme 74

1. Disconnect the battery ground cable. Refer to «Specifications»(/land-rover/range-rover/l322-2009-2012/remont/charging-system/#battery-and-charging-system-general-information) information.
2. Remove the floor console upper panel. Refer to «Floor Console Upper Panel»(/land-rover/range-rover/l322-2009-2012/remont/gauges-instrument-panels/#instrument-panel-and-console) article.
3. Remove the ride and handling optimization switch. Remove the 6 screws.

INSTALLATION

1. Install the ride and handling optimization switch. Install the 6 screws.
2. Install the floor console upper panel. Refer to «Floor Console Upper Panel»(/land-rover/range-rover/l322-2009-2012/remont/gauges-instrument-panels/#instrument-panel-and-console) article.
3. Connect the battery ground cable. Refer to «Specifications»(/land-rover/range-rover/l322-2009-2012/remont/charging-system/#battery-and-charging-system-general-information) article.

See also:
• Specifications
• Floor Console Upper Panel