I would first check the fuses and the relays related to the 4wd system.
Pull off the plug on the front diff clean it up and Di-grease it.
Also look for any cracks or worn off insulation on the wires connecting the diff.
There also could be an issue with the switch it's self.

 

But I hear the actuator working and my diff lock hasn't worked for a while now

 

If the Diff. is engaged, it could be the drive shaft as mentioned before.
Jack the grizz off the ground and see if the front shaft turns with the back to transfer power. Or in 2x4, see if it turns with the rear. If it's in the air, you can turn the front tires with the Diff. engaged to see if the drive shaft turns to the motor. There are a lot of combinations to try to isolate the problem.

 

If your diff lock has been down for awhile and now 4x4 is gone completely and , you can hear the actuator working I would have to assume your problem is a failed actuator (they are lil plastic splines on a very little motor) or your engagement in the diff is bent. I would pull he actuator off and look at it. many threads on here about the front diff and the actuator motor.

 

There are 3 relays involved in the 4wd system if you are confident that all of the above checks out go to oleblues website he has videos on how to test and repair. He also is a forum sponsor and has parts.
501parts.com - Yahama Servo Motors
The 4wd testing procedure is cover in the service manual as well.
Available at service manuals

 

Well guys went and pulled servo off and gears were good had some nice big chunks of ice in there that were causing my problems. 4wd working again not my diff lock tho but at least I can plow now with out getting stuck

 

We can figure why it won't go into diff lock. Like TRev said, if you can hear the servo motor turning when you try and go into diff lock, you have probably stripped the splines on the worm gear inside the servo assembly or you have a problem inside your diff. If you don't hear the motor turning when you press the button, it's gonna be one of your relays under the seat or a broken wire/bad connection on the switch and or wiring. You can test the relays and the switch with a multimeter You are welcome to give me a call at 5016580219.

 

Condensation from plowing. Unless you took it for a swim lately. :banana:
When the diff cools down it sucks moist air back in side. Make sure the vent tube is clean and up someplace high and dry.

Cheap fix =good newseace:

 

Hello guys I have a 2007 grizzly 700 the actuator is engaging and everything is working as it should for the electrical system in the 4 wheeler. The problem I'm having is I took the actuator off it is rotating back and forth, when I go from 2x4 to 4x4 and to the diff lock. The slide gear in the diff won't move the 4 wheeler sat for two years is it possible it froze up. And if so how to free it up thank you all in advance for your responses

 

Welcome to the forum. I would recommend in the future to start a new thread with any questions you might have. I would’ve never seen your question if I wasn’t subscribed as this thread is 5 years old or so.
To answer you question. If it were mine, I would drain the gear oil if there is any, fill the front diff with diesel and run it around the yard a few times. Chances are there’s some gunk built up in the diff. This will help break it free. Drain the diesel, and refill with gear oil. May have to do it a few times if it has a lot of gunk.
To get the slide gear to move over, Jack the front end up, take a big flathead screwdriver and try and pry it over as you rotate the front wheel. All the way to left is 2wd and right is diff lock.
If it won’t break free easy, take your time and soak it in something like PB blaster. Once you get it free, remember to put the slider all the way to the left and have the 4wd button in 2wd mode and the servo in 2wd mode. You have to have all three synced to 2wd.
Hope this helps.