Differential lock (diff lock)
Also called: locker, rear diff lock
A differential lock forces both wheels on an axle to spin at the same speed, so the truck keeps moving even when one wheel has no grip at all.
How it works
An open differential lets an axle's two wheels turn at different speeds (needed for cornering) but sends power to whichever wheel has the least grip. A diff lock forces both wheels on the axle to turn together, so both keep driving even if one is on ice or off the ground.
When to use it
Low-speed, low-traction situations — one wheel lifted or spinning. Engage at low speed; release for normal driving and turns.
Don't use it when…
Do not leave engaged on pavement or through tight turns — both wheels are forced to the same speed.
Pros and cons
Pros
- Dramatic traction gain in the exact situation that strands an open differential
- Simple and decisive
Cons
- Low-speed off-road only
- Must be disengaged for turns and pavement
- Factory fitment is limited to specific trims (e.g. the Suzuki Carry Nohan)
Compared to other systems
Against a limited-slip differential: absolute traction (a full lock) but it must be switched on and off, where an LSD works automatically. Against low range: a diff lock solves TRACTION, not torque — see the diff-lock-vs-low-range comparison.
See the full diff lock vs low range comparison for a side-by-side breakdown of these two often-confused systems.
The single feature that changes what a kei truck can do
Of every drivetrain feature on this list, a working diff lock is the one that most changes what a kei truck is actually capable of off the beaten path. The scenario it solves is exact and common: one rear wheel lifts off the ground or loses grip on mud, ice, or a rut, and an open differential — quietly, automatically, unhelpfully — sends all the power there, leaving you stuck with a wheel spinning freely in the air.
The misconception worth clearing up is that a diff lock is some exotic, hard-to-find feature. On a kei truck it almost always means one specific thing: a switch-operated rear locker fitted only to certain agricultural-grade trims, like the Suzuki Carry Nohan. If a listing simply says "4WD" without naming that trim, assume there is no locker — and if working off-road capability matters to you, that single word in the listing is worth more than almost any other spec on the page.
Models with this drivetrain
Trim-level mappings for this drivetrain are still being verified — confirmed models will appear here once the data is checked against factory spec sheets.