1996 chevy s10 4.3 . four wheel drive will not engage

Which of these does your vehicle have ?

Transfer Case - NVG 233-NP1 (Two Speed Selectable)
Transfer Case - NVG 136-NP4(One Speed Automatic)

The New Venture Gear NV233 is an electronic shift transfer, with the following three modes of operation, Two-wheel drive high range, Four-wheel drive high range, Four-wheel drive low range. The gear reduction for low range is provided by a planetary gear set. The floor-mounted shifter has been eliminated. A switch, located on the upper right side of the instrument panel, is used to select the operating range. The indicator lamps on the switch show the current mode of operation. When the four-wheel drive has been selected, the four-wheel drive indicator lamp on the switch is designed to turn on when the front axle has engaged.


Automatic Transfer Case
The single speed automatic transfer case system shifts automatically from rear wheel drive to four wheel drive when the transfer case shift control module (TCSCM) senses the difference in rotation speed of the front propeller shaft and the rear propeller shaft . Two vehicle speed sensors, one located at the rear output shaft area of the transfer case, and the other, located at the front output shaft area of the transfer case, send front and rear propeller shaft rotation speed information to the TCSCM.
When the front and rear output shaft rotations remain the same, the TCSCM sends pulse width modulation signals to the encoder/motor to keep the transfer case in rear wheel drive. When the front and rear output shafts rotations are different, the shift control module sends pulse width modulation signals to the encoder/motor to engage the transfer case into four wheel drive.
The system will automatically transfer a percentage of torque to either the front or rear axles as required to stop all wheel slip. When the front and rear output shafts rotations return to the same speed rotation, the shift control module sends pulse width modulation signals to the encoder/motor to position the transfer case back into rear wheel drive.
When the transfer case is engaged into four wheel drive, a lamp indicator on the instrument cluster will light. The automatic transfer case system is completely automated, no transfer case control button switching system is required.

Do you know what diagnostic trouble code's are ?

DTC C0300 Rear Speed Sensor Malfunction
DTC C0305 Front Speed Sensor Malfunction
DTC C0308 Motor A/B Circuit Low
DTC C0309 Motor A/B Circuit High
DTC C0310 Motor A/B Circuit Open
DTC C0315 Motor Ground Circuit Open
DTC C0374 General System Malfunction
DTC C0376 Front/Rear Shaft Speed Mismatch
DTC C0550 ECU Malfunction
DTC C0611 VIN Information Error
DTC C0895 Device Voltage Malfunction

Not OBD2 engine code's .

did you turn the locks on the wheels, or check the fuses

Try replacing the motor on the back of the transfer case that engages high/low, which should fix the issue.

Check the lever if is connected to the gearbox

are the lights flashing?if so it can be scanned to see what code it has

I would suspect you have a bad wheel speed sensor or a speed sensor defective... do you have an ABS/CheckEngine/4 wheel drive light on somewhere on the vehicle display... That might help fix the problem.

push button type floor shift type high range2wd does transfercase motor make noise did you burn transfercase clutches out? front not engaging but low range for rear help us help u

because when engaging low range on 4 wheel drive vehicle you should be standing still.

On small shift behinde gear lever there is 3 settings. H4 = 4 wheel drive high range, L4 = 4 wheel drive low range, h2 = 2 wheel drive high range. as soon as jou engage to 4 wheel drive a green light on the dash board will appear to indicate that the car is in 4 wheel drive. if not check fuse - check air pipes at front wheels. Enjoy Willem Sa

if it is electronic there is probably something wrong with the wiring..

but if it is manual...it might be the actuator........