Video: How and When to Use Your Car's Four-Wheel-Drive System

Now, if you have a vehicle with the type of all-wheel drive or four-wheel drive that has no controls, then you have nothing to worry about. I'm talking more about the more classic hardware that has controls and requires the driver's intervention, and nothing requires more driver intervention than a mode called part-time four-wheel drive. It is much more common in off-road vehicles like this Jeep Wrangler and in most pickup trucks. (upbeat music) The term part-time four-wheel drive is appropriate because it's a mode that you can use only part of the time. The reason is when you put it into part-time four-wheel drive, usually marked 4H or 4-high, it splits the power evenly between the front and rear axles which is great if you're on loose surfaces, but if you go to turn the vehicle, it doesn't allow the front and rear wheels to turn at different speeds which is necessary. Now, if you're on snow or ice or dirt or sand, that's fine because there's a lot of slippage. But if you take the vehicle onto pavement or hard-packed dirt, something different happens. When the vehicle is in part-time four-wheel drive, I can go straight without a problem because the wheels are all turning at the same speed and even make a kind of a gentle turn. But if I start to turn the wheel a little bit further, you start to feel the wheels fighting each other, the front and rear wheels, and there's a bucking sensation and the tires are kind of scrubbing against the ground, sometimes you can hear it. This is what can cause the damage, and as you can imagine, if you are taking a high-speed turn and your wheels aren't spinning freely, that can be a one-way ticket into a roadside ditch. Now understand that there are a lot of four-wheel drive systems out there, and many of them have provisions, so you can leave them in four-wheel drive all the time, they actually are more common than the part-time only systems. And now for 2018, for the first time, even the Jeep Wrangler is offering one of these modes called full-time four-wheel drive between the two-wheel high and the four-wheel high part-time mode, it's just called 4H auto. Typically, if you see on a vehicle 4A or auto or all-wheel drive, that means that is a mode you can leave it in all the time and not worry at all. As for the L, which you might see in a lot of four-wheel drive systems, that's four-wheel low gear that is not for snow or rain, it's typically for climbing over obstacles or maybe pulling a boat, up a boat launch on a trailer, most people will never ever use that. So if you're a normal driver just dealing with fall weather, you're going to want to put it into part-time four-wheel drive, only when you need it or put it in an auto mode and it'll take care of the rest for you.