I'm a little confused about this. Book states not to engage front diff unless stopped. Dealer states it is less strain on the system if you are moving a little but not over 5MPH. ( Helps gears engage easier he says ) Im not talking about the locker. Does the book make this statement to prevent injury or to prevent possible damage to the system ? My goal is to prevent damage. Any thoughts appreciated.

 

You need to be moving to engage and dis-engage the 4wd.

The only thing you need to watch is don't engage it when the wheels are spinning (that's why they say do it stopped). I just let off the gas for a second, and flip the switch. FYI, it automatically goes into 4wd when you lock the diff.

Realistically, it won't engage unless you are moving, and it won't disengage if you park on a slope (so that the drivetrain has strain on it).