weird 4wd problem

just wanted to double check with you guys since you are the experts. i have a 2000 lt 4x4 by the way. i have searched and read a lot of the posts about the electronic 4wd acting up on our trucks, but my problem seems to be a little bit different. i just got in my truck today and started it and it was in 4LO. it would not go out of 4LO when i hit the switch on the selector, so i turned the truck off and then back on and i had it in neutral while pressing the switch and it worked. since then , it has stopped functioning completely since i put it back in 2HI. the switch blinks all the lights when i first turn on the truck, then it goes to 2HI where it belongs. then, i cannot switch it to anything else. nothing blinks, nothing moves, nothing. then, a little ways into driving the SERVICE 4WD light comes on. whats even more strange is that when i pull the fuse for the 4WD, then plug it back in while holding down a particular button on the selector, it switches to that and i can hear it working. then once i try to switch again it will not work and i get no response. i then have to unplug and re-plug in the fuse and it will work again for one time only. anyone ever seen this before? is it the usual switch on top of the transfer case or the vacuum switch under the battery, or does this sound like something different? because it does work, i just have to do some weird stuff to get it to work. any and all advice and input is much appreciated because i do not want to damage anything. thanks!

Not for sure what transfer case you have but most of them can be checked out on a good engine/trans capable scanner.
Check for codes and a lot of scanners have some test you can run on it.
And check the wiring going to it.
If you can get codes post back codes or what transfer case you have.
MT-2500

i have the autotrac, sorry forgot to mention that in my first post. (auto 4wd, 4hi, 4lo, 2hi) thanks.

It is a full computer controled stransfer case NV236
Get it on a good engine/trans capable scanner and check for codes.
If you can get any codes post back.
MT-2500

hmm where can i do that? i am guessing my only option is the dealer... i have an appt monday, would they charge me a lot for something like that??

A dealer can do it but it is going to cost you. usually around a 100$+
Most good repair shops and or a good trans shop can can test it for you. Should be a little better price.
Even some parts places rent scanners but make sure it is a engine and trans capable one.
Not all scanners are.

still having the problem. replaced the tccm and still the same problem. now its weird, i cannot get it back into 2hi at ALL, it will only stay in 4hi or auto 4wd. if i unplug the atc fuse and re plug it in, it resets to 4hi and stays there, will not switch to 2hi. i can only switch it back to auto 4wd again and it will not move from there unless i unplug the fuse again. i have sat there for 10 minutes pressing the 2hi button and i get no response at all from anything, the light doesn't even blink. does this sound like a faulty dash switch to you, because in most of the other cases i have heard of the buttons at least flashing when pressed, even if they only flash and return to the previously selected button. this sounds like the only instance of this particular problem ever occurring, but im sure someone out there knows whats going on here. im so low on money i cant even afford to bring it to get the codes from the service 4wd light, so i want to get everything out in the open here first, thanks so much guys!

have you tried puting the blazer in netrual and then try to get it in 2hi

Go to autozone and have the codes scanned for free...

finally found the problem... it was my selector switch!! that was the last thing i thought would be wrong with it. oh well, i have just solved 3 months of headaches anyway, thanks for all the help everyone!