Won't go out of 4 wheel drive

If you are driving in 4 wheel drive on hard surface then you have drive line torque lock up as there is no centre diff to allow the front and rear wheels to equalise out the torque . 4 wheel drive is for use when on dirt / snow / ice where the differences between the front and back are allowed to slip the tyres . Jack up a rear wheel and allow the torque to dissipate by rotating a wheel . A point from all 4x4 manufacturers is that you NEVER drive in 4 wheel drive unless you are on dirt or ice/snow conditions. You have probably been getting away with it as any bump that lifts a wheel from the road surface will allow the wheel to slip. Even running the tyre on the white painted line on the road or any wet patch on the road will help ease the torque loading

when the actuator goes, usually the fuse goes as well, check your fuses.

Just to confirm, you don't have an electrical 4WD selector; you have to move a shifter on the floor of our cab? If that's the case, I'd suspect that you have a linkage misalignment or malfunction that doesn't allow the 4WD selector to completely return to the 2WD position. Putting the truck into reverse and back to drive probably causes a jolt to the 4WD linkage which disengages the transfer case from the driveline. Check for slack or binding in the transfer case shift level linkage (clean and lube the linkage won't hurt).

bad transmission maybe. Try going into a lower gear (2 or 1) and giving it a little gas and holding it there. (about 2500 rpm) Hold it there for about 30 seconds.
If it still doesnt move, look under at the side of the transmission where the shifter cable connects and make sure it is moving.
Make sure the brake is on and the wheels are blocked and have a friend shift it back and forth while you look.
Sometimes, the connection pin comes out and you wont shift. .
If it does move right away, head to the transmission shop.

Shift the transfer case to N while it is making the noise. If the noise goes away the transfer case is the culprit.

you can shift on the fly from 2 hi to 4 hi at any time as long as you are not under power or in other words on the gas. Hold at a steady speed or let up on gas pedal a little bit then shift, DO NOT shift truck when vehicle is speeding up or taking off. Also do not shift when wheels are spinning or when you are turning a corner. The same goes for shifting from 4 hi to 2 hi. ** Now to shift into 4 lo the truck should be stopped and put trans shift into nuetral then shift transfercase into 4 lo, and never exceed 25 mph in 4 lo position !!!!!!! To shift out of 4 lo and go to 4 hi or 2 hi stop vehicle and shift trans into nuetral then make your 4x4 shift then put trans into forward or reverse gear and VROOOOOM your on your way. Remember to NEVER and i mean NEVER shift into 4 lo while vehicle is moving forward or reverse as you will do serious damage to any and all parts of drive train. You should not run 4x4 at all unless you need to pull something where you need extra traction like a boat out of water,a stuck vehicle,or if roads are slippery, or muddy. also don't be alarmed as sometimes when in 4 wheel drive and you turn corners you will notice a binding or jerking motion, this is normal and if this is occurring i would recommend going back to 2 hi position. HAPPY TRAILS to you with the new toy. I only buy vehicles with 4x4 and have never owned a 2 wheel drive in my 31 yrs of driving. I love the idea that i have extra power and traction options when i need it,the only bad thing is your boss says " what do you mean you can't make it in,you have a 4 wheel drive!

the clutchs in the trans. It will most likely need a transmission

When you are finished with your 4 wheel drive,put the transmission in neutral, disengage 4 wheel drive and shift to reverse then back up a couple feet before shifting to forward gear.

When this happens I would think you have an issue with your 4 wheel Drive that needs servicing.Most of the time it's the selector switch($400),See if a National Chain( transmission )has free or low cost evaluations.Good Luck.

Check fluid level in transfer case.