terrain response system

Terrain management system is an electronic system that adjusts engine torque, traction control, all wheel drive system, and other settings to provide better off-road performance on a particular surface (gravel, mud, snow, sand).

Land Rover introduced a Terrain Response system on its Discovery in 2005.

Figure: Terrain Response mode selection knob (top), yellow HDC button, on the left - suspension height adjustment switch, and low gear switch on the right (60KB)

Figure: Terrain Response status is displayed on the dashboard (37KB)

Discovery, Freelander, Evoque, Ford Explorer, and Jeeps are known to have a terrain management system installed (either as standard or optional feature).

Dynamic Mode - optimizes driving performance on dry, paved roads. (Range Rover Evoque only)

General Program - The General Program is for use on dry, solid surfaces such as paved highways. This program is the ‘default’ program, meaning that if another Terrain Response setting is desired, the system should be set to the General Program. In fact, Land Rover warns that driving the vehicle with an incorrect setting can impair drivability and reduce the life of the suspension and drive systems.

Grass/Gravel/Snow - This program is for use on loose or slippery surfaces, but not deep soft materials such as deep sand or deep snow. Land Rover recommends using the Sand program for deep snow. The most common terrain surface that correspond to this setting are just as the name suggests: wet grass and snow-covered roads.

Mud/Ruts - The Mud/Ruts program is for deeper mud, ruts, and uneven surfaces.

Sand - This program is for soft, deep surfaces. Wet sand (such as on a beach) may require the Mud/Ruts setting. The Sand program is also the preferred program for snow that is deep enough for the tires to “sink in” when attempting to gain traction.

Rock Crawl - (except Range Rover Evoque) The Rock Crawl setting is for use on solid surfaces when careful control is needed, whether wet or dry (large rocks, rocky river beds, etc.). Rock Crawl is available only when the vehicle is in Low range.

Land Rover’s Terrain Response system integrates:

• Dynamic Stability Control (DSC)
• Electronic Traction Control (ETC)
• Hill Descent Control (HDC)
• Gradient Release Control (GRC)
• Hill Start Assist
• Roll Stability Control (RSC)
• Air suspension height adjustment (where available).

Ford Explorer’s Terrain Management System is a simplified derivative of the Terrain Response system of the Land Rover. It offers no low range and no air suspension.

The user interface of Ford’s Terrain Management System is almost identical to the Terrain Response system from which it is derived. It offers identical settings to the Land Rover system (sans Dynamic Mode and Rock Crawl), which are used for the same types of terrain. Ford even uses some of the same icon graphics on the selector dial.

Ford Terrain Management System Programs

• Normal
• Snow
• Sand
• Mud/Ruts

A single selectable traction control management system (Select-Terrain) is available with two feature packages (Off-Road Group I and II) on the following four wheel drive systems: Rock-Trac (Wrangler Rubicon), Command-Trac (Wrangler), Command-Trac II (Liberty), Selec-Trac II (Liberty), Quadra-Drive II (Grand Cherokee), Quadra-Trac I (Grand Cherokee), Quadra-Trac SRT (Grand Cherokee SRT8), Quadra-Trac II (Grand Cherokee), and Freedom Drive I and II (Liberty, Compass).

The Selec-Terrain system allows for Auto, Sport, Snow, Sand/Mud, and Rock settings. Jeep’s selectable programs are a little more intuitive than the Land Rover and Ford systems and come in two variations: Off-Road Group I and Off-Road Group II. We’ll be looking at the Selec-Terrain Off-Road Group II system; the closest analogy Jeep offers to full Terrain Response. The Off-Road Group II package includes an air suspension and electronic limited slip differential.

Auto - Auto is the normal driving program for use on all types of terrains. Torque is available on demand and the air suspension sits at normal ride height.

Sport - The sport setting optimizes vehicle response for dry, on-road driving. This setting gives the Grand Cherokee a rear-wheel drive feel but with the improved handling of a 4WD vehicles. This setting is most analogous to the Dynamic Mode setting on the Range Rover Evoque.

Snow - This setting is to be used on any loose surface, such as snow-covered or icy roads. The program attempts to minimize wheel slippage. This mode is similar to the Terrain Response Grass/Gravel/Snow program.

Sand/Mud - This setting is used for mud, sand, or wet grass. The setting maximizes traction by limiting traction control management of throttle and wheel spin. This program is similar to Land Rover’s Mud/Ruts setting.

Rock - The Rock setting is only available on Low range. This setting is used to navigate any obstacle requiring low-speed and careful control, such as large rocks, deep ruts, water crossings, etc. This program is similar to the Land Rover’s Rock Crawl setting.

Figure: jeep grand cherokee 2011 selec terrain controls (130KB)

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