I live near the ocean where we are allowed to drive on the beach. Do I need to change the selector to 4X4 before getting on the sand or just go? What triggers the auto switch?

 

I have never driven on the beach before living in Nebraska. The auto 4x4 works pretty simple. There are two speed sensors on the transfer case, one for the front drive shaft and one for the rear drive shaft. The transfer case has a set of clutches in it. The truck is in 2 wheel drive until the sensor for the rear drive shaft senses a different speed , the rear wheels slipping, than the front drive shaft. At that point the clutches inside the transfer case engage powering the front axle. As Alloro has pointed out it is not all that healthy for the TC going from 2 wheel to 4x4 to many times it is kinda jerky and it wears on the TC. These trucks weigh close to 6000 pounds and that is alot for the clutches to work to often. I change my TC fluid every 30,000 miles and it is burnt and I use Mobile one synthetic. So as Alloro suggested I will lock the TC into 4x4 high more in snow and not rely on the auto 4x4 and change the fluid more often.

 

As Omahastro1 pointed out so very well, yes you should. The use of A4WD is best for wet/rainy roads. For snow, ice, sand, or off-roading where you know there is going to be a lot of tire slippage, it's best to lock it into 4WD. On sand I would go a step further and put it in 4WDL instead of high. Sand creates a lot of resistance and drag. Switching into low will take a heavy load off both the engine and the tranny.

 

But, you can't go fast then, that's no fun

 

You can't go fast anyway, they'll throw you out of there faster than you can say, "surfs up"!!

 

Depends on what the sand is like. I've been on beaches where any car, even a motor cycle could be driven and I've been on some where I've needed to air down my tires to 10psi.

Not knowing the sand you'll be on, the suggestion I'd give is to air down your tire to around 15psi, put the truck in 4WD and go. Make sure to take a shovel, tow strap and a 12"x12"x1" piece of plywood with you in case you get stuck. Oh and have fun!!

 

Here, hold my beer and watch this.