- Engine management system - engine control unit (ECM)
- Transmission control system - transmission control unit (TCM) (only automatic transmission)
- Active clutch control unit
- Brake system - ABS control unit (anti-lock braking system (ABS) / dynamic stability control (ETC) / electronic traction control (ETC) / controlled descent system (HDC))
Each subsystem works differently, depending on the selected Terrain Response program, to provide optimal traction, stability and vehicle control in given road conditions.
Engine management system (EMS)
The EMS can change the accelerator pedal operation parameters to change the engine torque at the same pedal stroke.
Each Terrain Response program uses a combination of operating parameters for each subsystem. Changing the program entails a noticeable change in performance for the driver, for example: if you hold the accelerator pedal in the same position and change the program Grass/Gravel/Snow ("Grass/gravel/snow") for the Sand program ("Sand"), the driver will notice an increase in torque and engine speed. When switching from the Sand program ("Sand") to Grass/Gravel/Snow ("Grass/gravel/snow") the driver will notice a decrease in torque and engine speed.
NOTE: It may take up to 30 seconds for the engine torque and speed to change, so Terrain Response should not be mistaken for an EMS engine management system malfunction.
Gearbox control system (only automatic transmission)
The transmission control module changes the gearshift parameters in accordance with the selected Terrain Response program. This results in early or late upshifts or downshifts.
For example, in Grass/Gravel/Snow ("Grass/gravel/snow") the transmission will upshift early and downshift very late. This ensures the highest possible transmission. Descent detection function in the transmission control unit (TCM) locks up the torque converter and, if necessary, will hold the selected gear up to the engine speed limit on a steep descent. This provides maximum engine braking before the driver applies the brakes.
The sport mode is only available when the standard program is selected. Sport mode is not available with any Terrain Response special program enabled. Mode "CommandShift™" available with any program.
Active clutch control
The active clutch control unit has two operating strategies: active and reactive.
The look-ahead strategy predicts the amount of locking torque required to minimize slip and improve stability. Each Terrain Response system program has a specific threshold value and active strategy input criteria. For example, higher lockout torque will be used on slippery surfaces.
The reactive strategy changes the amount of locking torque depending on the actual level of slip and the dynamic behavior of the vehicle. Each program of the Terrain Response system has a certain threshold value and input criteria for a reactive strategy. The reactive strategy improves wheel traction by preventing wheel slip that occurs after the active strategy is applied. Lock options depend on the selected program. For example, high sensitivity on slippery surfaces to ensure maximum traction and minimize pavement damage.
The locking torque calculation uses various signals from other subsystems, such as engine torque, accelerator pedal position, gear selected, steering angle, vehicle speed, lateral acceleration, and yaw rate.
The DSC function of the ABS system can correct the operation of the active clutch control system and reduce the applied locking torque during DSC operation.
ABS control
The ABS control unit controls several functions and adjusts the operating parameters of these functions to optimize the selected Terrain Response program.
Traction control system
The traction control system uses different slip/acceleration thresholds to improve traction and vehicle stability. For example, to reduce wheel slip when driving on slippery surfaces, the sensitivity of the system is increased. If slippage is allowed under such conditions, loss of traction can lead to various consequences: from damage to the surface (wet grass) until it is impossible to continue driving due to wheel slip (snow).
Dynamic stability control
When the DSC system is turned off (DSC switch next to the Terrain Response rotary control) when using a special program of the Terrain Response system, the next time you switch to another program, the DSC system will automatically turn on again.
The DSC system uses different thresholds for the selected program to reduce its impact, eliminating the need for the driver to turn off Dynamic Stability Control to reduce engine interference, which is sometimes required in severe off-road conditions When driving in deep sand, it may be useful to turn off the dynamic system directional stability using the DSC switch, in addition to the inclusion of the Sand program ("Sand").
In Mud/Ruts ("mud/ruts") DSC system allows higher yaw threshold (twisting around a vertical axis). This allows you to increase the difference between the actual and desired rotation of the wheels before the intervention of the dynamic stabilization system (DSC). This allows the DSC system to ignore rut effects such as shock jolt or changes in front wheel angle.
The Terrain Response system can change the balance of engine and braking intervention. For example, if you select the program Sand ("Sand") The DSC system reduces engine intervention and increases brake intervention to maintain the vehicle's mechanical torque and prevent stalling when wheel spin is detected.
Descent control system
The activation and deactivation of the controlled descent mode and the selection of the set speed are carried out automatically depending on the selected program of the Terrain Response system. If necessary, the responsiveness of the HDC function is also improved.
The automatic operation of the HDC function is designed to assist the driver by turning the system on or off when it is most needed. HDC is automatically enabled only when Mud/Ruts is selected («mud/ruts»). In other programs, HDC does not turn on automatically.
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