Centre Differential Lock

[Runner Up]

My previous truck, which I miss dearly, was a 1995 Tacoma SR5. It was basically a TRD, before TRD existed. Man, I loved that truck.

Anyway, I'm not terribly familiar yet with the "new-fangled" 4-wheel drive system on my 2003 4Runner V6 SR5 4-speed. I read the user manual, and what I took from that was, if you want to shift into 4H, turn the knob (to the right of the steering wheel) from 2H to 4H. Then, if you want more traction, push the Centre Differential Lock button (to the left of the steering wheel). Ok.

My question is, what happens if you remain in 2H and push the Centre Differential Lock. Does it do anything? Does it hurt the drive train? Or does it lock the rear wheels, the same way a rear locking differential does? This isn't mentioned at all in the user manual.

 

[Mike07SE]

The way the drivetrain in the 4Runner is setup is that whenever you switch to 4H or even 4L and the center diff button isn't pressed you are in AWD mode. This means you can drive it on pavement without harm.

By locking the center diff in either 4H or 4L now basically gives you 4x4 which is unsuitable for pavement use do to it's inability to allow slip. Pushing the button in 2H will not allow anything to happen.

 

[Sungod]

The v8 4 runner is full time 4wd. You have differentials on both axles that are connected to center differential that delivers power to those axles. If you are familiar with the way differential work, you know that they deliver power to side with the least resistance. These open differentials allow traction control and skid control to function by use of ABS to insure that power is delivered to where you have traction vs a wheel that doesn't.

What the locking center differential does is it locks in the power delivery so that you are getting power delivered to both the front and rear axle. Because you still have open differentials front and rear, you can continue to drive on pavement because the power isn't being forced to a particular wheel. This puts you into a traditional 4wd configuration.

This is not an axle locker like the Tacoma or the previous gen of 4 runner that offered that as an option. In that situation, your axle had a mechanical locker that locked the differential so that both wheels turned equally.

 

[m85476585]

He has a V6.

It's not good to drive on dry pavement with the center locked because if you turn the front and rear axles want to rotate at different speeds. With the center locked, the drivetrain will bind up a bit, it will resist turning and moving, and usually one or more of the wheels will slip a bit. It's meant for maximum straight line traction on slippery surfaces. It's also not usually a good idea to lock the center on snow or ice because it will force one or more wheels to break free when you turn. It's most useful in situations like getting unstuck or difficult off-road driving.

 

[Runner Up]

Ok, thanks for the helpful information guys.

 

[Sungod]

He has a V6.

It's not good to drive on dry pavement with the center locked because if you turn the front and rear axles want to rotate at different speeds. With the center locked, the drivetrain will bind up a bit, it will resist turning and moving, and usually one or more of the wheels will slip a bit. It's meant for maximum straight line traction on slippery surfaces. It's also not usually a good idea to lock the center on snow or ice because it will force one or more wheels to break free when you turn. It's most useful in situations like getting unstuck or difficult off-road driving.

oops, missed the v6 part. Same is true for the v6 as the v8 except you have the ability to switch from 2 to 4wd. When it is in 4wd it functions the same as the v8.

You may want to review this to learn how differential work: Welcome to Land Cruiser Owners On Line