How to shift from 2wheel drive to any of the 4 wheel drive modes thank you

Does it shift to 4wd high range ? If so then shift to 2wd . What is going on here is the transfer case motor is stopping due to the motor position sensor has gone bad which means that you replace the transfer case motor assembly. But if you wish to make it a 2wd for awhile then remove motor and manually turn shaft . This can be done by raising and supporting rear axle truck in park remove motor turn shaft slowly with pliers and rotating the play in drive shaft. There are stamped markings on back of case showing gear positions..

check your oil level may be low.

Pulling code's from the 4X4 control module would point to a diagnostic procedure . Do you own a professional type scan tool that can read DTC'S - diagnostic trouble code's in the 4X4 control module ? Autozone , advance etc.... can not read these code's .
Which transfercase does it have ?
Transfer Case - BW 4482-NR4
Transfer Case - NVG 246-NP8

How many buttons for 4X4 three or four ?
The BW 4482 transfer case features a 3-button shift control switch located on the instrument panel
The NVG 246 EAU transfer case features a 4 button shift control switch located on the instrument panel
When the ignition key is in the RUN position, the transfer case shift control module monitors the transfer case shift control switch to determine if the driver desires a new mode/range position. At a single press of the transfer case shift control switch, the lamp of the new desired position will begin flashing to inform the driver that the transfer case shift control module has received the request for a new mode/range position. The lamp will continue to flash until all shifting criteria has been met and the new mode/range position has been reached, or has been engaged. Once the new mode/range position is fully active, the switch indicator lamp for the new position will remain ON constantly.The 4X4 system with four button shift control can set a number of DTC'S
DTC B0790
DTC B2725
DTC C0300
DTC C0305
DTC C0306
DTC C0321
DTC C0327
DTC C0359
DTC C0374
DTC C0379
DTC C0550
The three button switch can also set an store a few codes
DTC B0790
DTC B2725
DTC C0306
DTC C0327
DTC C0329
DTC C0359
DTC C0550
Without knowing if any of these DTC'S are stored can't suggest any type of repair .

does it have auto hubs, if so check the vacuum switch at tranny side

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This will require the help of a assistance. With the engine turned off, set parking brake . Have your assistance turn the key to the on position (motor off) and turn the 4 wheel drive switch to 2 wheel,next apply brakes and shift vehicle into neutral. While your assistance continues to hold brake petal on crawl under your truck and locate the transfer case. on the back side of the transfer case there is a electric motor, using a hammer moderately rap on shift motor (ON the area of the motor its self) If you now hear it shifting and it shifts back to 2wheel drive your transfer case motor needs replaced. thanks for using fix ya

It is the shift motor for the 4wheel drive - only problem is that a shop has to program the new shift motor to the blazer or it will keep doing the same thing

take a standard screwdriver apply pressure to the whole switch panel towrds the drivers window then repeatedly push the 2 wheel drive button until the low lock button flashes then keep on pushing 2wheel drive button til it shifts you can tell its out by cranking steering wheel all the way to either end of travel and move foward no binding means your out

try turning the steering at a complete stop fullly left and right. If the steering is resistnt then you are in 4 wheel drive. vehicles in 4whl drive don't like to steer unless they are moving.

this is common on these trucks just put your witch in 2 wheel and go ahead and drive it will let loos when it sees the correct secquence and drive a little and shift to netural.
just neve do it from high to low range

I had that problem in my 1998 Blazer. There is a module on the passenger side of the truck, next to where the passenger right foot be. Remove the side kick panel to get to module. Disconnect battery before unpluging and pluging new mudule in. This unit controls the electronic switching between 2 and 4 wheel drive..Wes