2000 Blazer 4X4 issues please help snow on the way

2000 blazer 4dr 4X4 4.3l v-6... The other day I noticed that my service 4wd came on, I turned the ignition off and when started again the light went off. Next day light came on and stayed on. I shifted to 4HI but then couldnt go back to 2HI or any. Yesterday I tried to go to auto4HI and it did I heard it click so I left it there since i didnt want to get it stuck in 4Hi again. I checked in the snow in my driveway and the front wheels are spinning the the 4wd seems to work. I need to get this fixed asap as I live in Erie PA and snow is on the way. First, my haynes book says I have a NVG236/246-NP8 transfer case. I was thinking of taking it to the chevy dealership to see if they can scope it and find the code for what is wrong with it. I'd like to know where to check the fluid level for the transfer case and what does it take, the book says dextron 3 tranny fluid? Are there any fuses i could pull and reset and where are they located? What about the location of the TCCM, vacum actuator, encoder motor/switch? Any ideas about what the problem could be? I need to fix this asap SNOW is comming...I only want to take it to dealership as a last resort. Any help/info is greatly appreciated.

2000 blazer 4dr 4X4 4.3l v-6... The other day I noticed that my service 4wd came on, I turned the ignition off and when started again the light went off. Next day light came on and stayed on. I shifted to 4HI but then couldnt go back to 2HI or any. Yesterday I tried to go to auto4HI and it did I heard it click so I left it there since i didnt want to get it stuck in 4Hi again. I checked in the snow in my driveway and the front wheels are spinning the the 4wd seems to work. I need to get this fixed asap as I live in Erie PA and snow is on the way. First, my haynes book says I have a NVG236/246-NP8 transfer case. I was thinking of taking it to the chevy dealership to see if they can scope it and find the code for what is wrong with it. I'd like to know where to check the fluid level for the transfer case and what does it take, the book says dextron 3 tranny fluid? Are there any fuses i could pull and reset and where are they located? What about the location of the TCCM, vacum actuator, encoder motor/switch? Any ideas about what the problem could be? I need to fix this asap SNOW is comming...I only want to take it to dealership as a last resort. Any help/info is greatly appreciated.

If you have a 236 do not use dexron 111.
It takes special GM transfer case fluid.

First you need to make sure it is a 236.
They have a ID tag on back of transfer case and also a check fluid level plug about a 1/3 way up on back transfer case.

Does you push buttons have a auto 4W buttion on them?

If a 236 you will need to find a repair shop with a transfer case capable scanner to get codes and test out shifting.

Post backanycodes you have.