Computers have been part of cars since the ‘90s, in terms of electronic driving aids for on-road use. But only recently have they appeared for off-road driving. Take note that they still require a lot of off-road driving knowledge to be properly utilized. Below is a list of what one may commonly find on true 4WD vehicles, as well as some new features reserved for the more expensive brands.
1) Electronic traction control (ETC). It’s now found in almost all 4WD vehicles (and in some 4x2s) and is usually confused with electronic stability control (ESC). Both systems are found on vehicles with ABS. What differentiates them is that ETC does not cut engine power and applies brakes when used off-road. Most vehicles have a kill switch for stability control, while others automatically turn it off when 4WD low gear range is engaged. ETC works by applying the brakes on the tire that has the least traction and passes the driving force to the opposite tire. The downside of this system is because of the automatic brake application, it impedes forward momentum when you need it most.
2) Electronically engaged center differential locks. This feature is what separates real 4WDs from all-wheel drive vehicles, and is usually found in the former. It automatically locks the front and rear axle mechanically to make them both spin at the same time. In most vehicles a switch or a button is required to use this, but some models activate it automatically once the 4WD controls are switched to automatic or 4WD low.
3) Terrain management system. This is usually found in AWD vehicles that claim to have true off-road capability. It works by adjusting how the engine, transmission, and brakes will respond based on the driver's settings. Terrain management operates separately from the transfer case and is ideal for light to moderate off-road driving conditions. Continued use on very severe to extreme conditions can result in the automatic transmission fluid overheating, and will temporarily impede the use of the vehicle for a few minutes to cool down. These conditions is why there's a need for the center differential lock.
4) Hill start assist. Basically, this delays the release of the brakes once a 4WD vehicle is on a steep slope for a few seconds. So in the event that the driver makes a failed hill climb, the vehicle doesn’t immediately roll back when transitioning from the brake pedal to the accelerator.
5) Obstacle warning alarms. It works like a parking sensor but is more sensitive in detecting rocks, branches, and even the ground that you are driving on to warn you if you are near an obstacle. They can be so sensitive that a small leaf can trigger the warning tone in highly vegetated conditions and can be really distracting at times.
6) Off-road cruise control. In a nutshell, it maintains the speed of the vehicle depending on the driving conditions. In some vehicles, it can be determined by the gear you select.
7) Intelligent manual transmission. I personally have only seen this on Toyota 4WDs. What it does is match the engine speed to the wheel speed of the vehicle for a smoother transition between gears, resulting in better traction and it makes you look like a skilled driver.
8) Automatic off-road mode. Only found on 4WDs in the premium price range, it takes the guesswork out of all the aforementioned aids as the vehicle does the thinking for you. It’s a prelude to autonomous off-road driving.
So there you have it. Bottom line is, know your vehicle and learn how all these aids will help you in off-road driving conditions.