Guide
How to use 4WD low range and diff locks: 2H, 4H, 4L explained
A plain-English explanation of four-wheel-drive systems for Australian drivers: part-time versus full-time 4WD and AWD, when to use 2H, 4H and 4L, how to engage low range, centre and rear differential locks, traction control, and the mistakes that cause driveline damage.
Published
In a typical part-time Australian 4WD, use 2H on sealed roads, 4H on loose surfaces such as gravel, dirt and sand at normal speeds, and 4L (low range) for slow, technical driving: steep climbs and descents, rocks, water crossings and recoveries. Diff locks are for the moments when a wheel lifts or spins; engage them only when needed and disengage them once you are through.
That is the short version. Systems differ between vehicles, so your owner's manual always overrides general advice. This guide is part of our 4WD beginner's guide.
Know which system you have
Four broad systems are common in Australia:
| System | How it works | Typical examples |
|---|---|---|
| Part-time 4WD | Rear-wheel drive by default; front axle locked in when you select 4H or 4L. No centre differential | Many dual-cab utes and older wagons |
| Full-time 4WD | Drive to all wheels all the time through a centre differential, which can be locked; usually has low range | Many large wagons |
| Selectable or multi-mode 4WD | Offers 2H, an "auto" 4WD mode and locked 4H/4L | Some newer utes and wagons |
| All-wheel drive (AWD) | Automatically sends drive to all wheels; usually no low range | Many SUVs and crossovers |
Check the manual for your specific model. Our vehicles hub covers common platforms, and the vehicles and mods board is the place to ask owners of the same model.
2H: everyday driving
On a part-time system, 2H is your default for sealed roads and most well-graded dirt roads in dry conditions. It gives the lightest steering, best fuel economy and least wear.
4H: loose surfaces at normal speeds
Engage 4H when the surface is loose or slippery and you are travelling at normal speeds: gravel roads, corrugated dirt, sand runs on a beach, wet grass. Four-wheel drive improves traction and stability, particularly when braking and cornering on loose surfaces.
Do not use 4H on bitumen or other high-grip surfaces in a part-time system. Without a centre differential, front and rear axles cannot turn at different speeds through corners, causing driveline wind-up. You may feel it as tight steering or tyre scrubbing, and over time it can damage components. Full-time systems avoid this through the centre differential, but lock the centre diff only on loose surfaces.
4L: slow, technical driving
Low range uses a reduction gear in the transfer case to multiply torque and lower road speed for a given engine speed. That gives you:
- Control at walking pace without riding the clutch or brake
- Engine braking on steep descents
- Torque for climbs, rocks and soft sand starts
Use 4L for steep climbs and descents (see our hill climbs and descents guide), rocky or rutted sections, water crossings, soft sand starts and most recoveries.
How to engage low range
The procedure varies, but a typical sequence is:
- Stop, or slow to a crawl, as your manual specifies.
- Put an automatic in neutral, or depress the clutch in a manual.
- Select 4L with the lever, dial or button.
- Wait for the indicator light to stop flashing and stay on.
- Select drive or first gear and move off gently.
If the indicator keeps flashing, roll forward or back slightly to let the gears align. Never force a lever.
Differential locks
Open differentials let wheels on the same axle turn at different speeds, which you need for cornering. The downside is that drive follows the path of least resistance: if one wheel lifts or sits on slippery ground, it spins and the other stops.
- Centre diff lock (full-time systems): locks front and rear axles together for loose surfaces.
- Rear diff lock: locks both rear wheels together. Useful when a rear wheel lifts on cross-axle ruts.
- Front diff lock: locks both front wheels together. Makes steering heavy; use only in specific, slow situations.
Good habits: engage lockers before you need them on an obstacle, not halfway up; use them at low speed, usually in low range; drive straight where possible; and disengage as soon as you are through. A locked axle resists turning and can make the vehicle push straight ahead.
Traction control and terrain modes
Many modern 4WDs have electronic traction control that brakes a spinning wheel to send drive to the other side, plus terrain modes for sand, mud or rock. These systems are effective, but they behave differently from mechanical lockers. Some vehicles disable traction control when a rear locker is engaged. Learn how your vehicle's systems interact before you need them.
Tyre pressures matter more than gears
No gear selection will compensate for incorrect tyre pressures. Lower pressures increase the tyre's footprint, improving traction and comfort off-road and reducing track damage. They also reduce load capacity and require lower speeds. Our tyre pressures guide explains how to choose starting pressures and why you must reinflate before returning to the road.
Common mistakes
- Driving in 4H on bitumen in a part-time system.
- Using 4H where 4L is needed, then riding the clutch or brakes.
- Engaging lockers at speed or leaving them on.
- Forcing the transfer lever instead of letting gears align.
- Relying on electronics without understanding their limits.
- Forgetting to return to 2H (or disengaging free-wheeling hubs where fitted) back on the road.
When to get help
If your 4WD indicator light keeps flashing, you hear grinding when changing range, or the steering binds on loose surfaces, stop and consult your manual or a qualified mechanic. A 4WD training course will give you hands-on practice with your own vehicle in a controlled setting.
Where to go next
Frequently asked questions
When should I use 4L?
Use low range (4L) for slow, technical driving where you need control and torque: steep climbs and descents, rocky sections, deep sand starts, water crossings and recoveries. Use 4H for faster, loose surfaces such as gravel, sand runs and dirt roads.
Can I drive in 4H on bitumen?
Not in a part-time 4WD system. Without a centre differential, driving in 4H on high-grip surfaces causes driveline wind-up that can damage components. Full-time 4WD systems can be driven on bitumen with the centre diff unlocked. Check your owner's manual.
Do I need to stop to engage low range?
Most vehicles require you to stop, or be almost stopped, with the transmission in neutral or with the clutch depressed before shifting into low range. Procedures vary, so follow your owner's manual.
When should I use the rear diff lock?
Engage a rear locker when wheels are lifting or spinning on uneven ground at low speed, typically in low range. Disengage it as soon as you are through, because a locked axle makes steering harder and increases tyre wear.
Is AWD the same as 4WD?
No. All-wheel-drive vehicles send drive to all wheels automatically but usually lack low-range gearing, locking differentials and the ground clearance of a dedicated 4WD. They suit graded dirt roads, not technical tracks.