Help with 4wd

I posted this under 1st Gen Toyotas, and was referred here, maybe y'all can help me, I'm having trouble with my 4wd. When I'm driving, the 4wd will engage on its own, and it's not just the light, the 4wd is kicking in and out, the motor drags down, it pulls in the turns, and sometimes pops when it comes out.
https://m.youtube.com/watch?v=sdwT1PbeLN4
If y'all can help me in any way I'd greatly appreciate it

 

Its me again, hoping that posting over here might help you.

I've been on TW for many years and it used to be a good source of technical knowledge. One could post a tech question like yours, and many guys would attempt to help, posting differing solutions, argueing back and forth. All of it was informative AND entertaining.

However, I think that most of the guys who offered good tech assistance have left TW, or just don't
seem to want to take the time to post solutions. The forums seem to be dominated by
non-topic chit-chat, and cosmetic 'upgrades'.

That being said, I found this video on youtube that discusses your non-manual type of 4wd system. It doesn't address your exact problem (which is a baffler) but it does discuss the components involved, and might help you understand your set-up.

https://www.youtube.com/watch?v=xAhmebST-a4

 

Thank you again, I'll watch the video and try to figure it out myself. If I can't figure it out I may just have to replace the parts involved, which I know will be really expensive

 

Don't just start replacing parts. Learn how it all works (do you have a FSM?), test each component, and replace the one part that fails the test. You could take it in to a local independent mechanic (not the dealer) who specializes in Toyota, and pay them to diagnose. Then order and replace the part yourself.