1994 sonoma 4x4 exd cab

this may assist you engage in 4x4 and reverse for a few meters, normally this does the trick on the transfer case if not then either the electrics/switch to the transfer case is not not functioning or the transfer case itself.

small trucks like that are considered 1/4 ton. silverado 1500 1/2 ton an silverado 2500 3/4 and up. same goes for gmc

Go under the truck and inspect all wiring to the Transfer case actuator motor.

These 3 things are common on S 10 and S15 GM 4x4 trucks and SUV's!

1.Switch in dash.
2. Actuator motor on transfer case.
3.Vacuum leaks between Engine,Transfer Case and Front axle actuator.

I'm betting they are different lengths and different size u-joints,

Well this could be numerous things..

Does the vehicle make any kind of noise when you try to shift it into 4x4? Do the dash lights on the push button shifter light up?

It is very common for the transfer case shift motor to go bad on these. They are located on the side of the transfer case by 3 or 4 10mm bolts. Another possibility would be the plunger on the front differential is bad. This is located on your front carrier assembly. It screws right into the side of the housing.

If you aren't sure I would take it to a good shop and mention these 2 things and they will take care of you.

Good Luck!

Check the fuse to the 4x4, if the fuse is good then check the 4x4 electric motor actuator on the transfer case. You should hear it work from 2wd, 4hi to 4low and back to 2wd with the push of the switch. if you don't hear it working then check the wire harness at the actuator motor, look for any damages like corrosion or cracked wire connector clips. If the 4x4 actuator is working on the transfer case, then the front hub 4x4 actuator may have gone bad and that's located on the front differential. It's common for the clip there to corrode and break and is an easy fix with a new collar pin, at worst it's the diaphragm on the vacuum actuator that is located under the battery tray. There is a vacuum switch on the top of the transfer case, driver side but when that fails, your front hub stay's locked in the on position. Good luck and keep me posted and hope it's a simple fuse that has gone bad. You can pick up all these parts at Auto Zone or Parts Source and they will have the step by step instructions for you to get the job done with common tools.

03 sonoma will not go in 4hi but will go in 4lo

no you should not have to drop it. there should be a slip yoke with the shaft leading from the transmission to the transfer case. when you remove that and support the transfer case there will be plenty of room to move the transmssion back away from the engine to remove it

yea its not shifting again like before ? sounds like your transfer case solonoid has possably gone bad again .. these are a sometimes dont work item .. It is what shifts the transfer case into gear and it might be a little worn or weathered and not letting the switch kick it in gear all the way from the N position. thanks Jerry holler if you need more.