Originally Posted by Jetboy

I don't think the computer will let you screw it up. Someone can probably confirm, but I think if you're over 55, it won't shift into 4hi until your speed drops. I have a trail edition with the lever. I engage at any speed - I've done it at 70mph with no issues. Lots of times. There's an internal clutch that brings the rotating assembly up to speed. So when the dog clutch teeth engage internally they're already synchronized in speed before they engage. The same is true for the front axle disconnect.

The 4Lo - that one you need to be stopped for. And in neutral. I'm sure the electronics won't let you engage at speed. That would cause a catastrophic failure. But there's no way Toyota would setup the electronics to allow that to happen if you just moved the dial to the wrong spot.