I need to know what to do to get the 4x4 to work.

yes you can what year is your truck? you will need around the same year truck to make it easier ... you need the front axle drive shaft and suspension components, as well as to be a decent welder. you need a 4x4 transfer case drive shaft and the output shaft from a truck with 4 wheel drive. other than that all you need is $$..best way to go is find a cheap 4x4 with a blown engine and swap, or trade yours for a 4x4... its a lot of work

The Selectable Four Wheel Drive (S4WD) Front Axle consist of the following components:
• Differential Carrier Housing
• Differential Case Assembly
• Inner Axle Shaft
• Intermediate Shaft Bearing Assembly (located on the right side of the oil pan)
• Electric Motor Actuator
The front axle on Selectable Four Wheel Drive (S4WD) model vehicles uses a disconnect feature mounted on the right side of the oil pan in order to engage and disengage the front axle. When the driver engages the 4WD system, the Transfer Case Control Module sends a signal to the electric motor actuator to energize and extend the plunger inside. The extended plunger moves the clutch fork and clutch fork sleeve across from the clutch fork outer gear that is splined to the right side wheel drive shaft to the clutch fork inner gear that is splined to the inner axle shaft. The locking of the two gears allows the axle to operate in the same manner as a semi-floating rear axle. A propeller shaft connects the transfer case to the front axle. The differential carrier assembly uses a conventional ring and pinion gear set to transmit the driving force of the engine to the wheels. The open differential allows the wheels to turn at different rates of speed while the axle continues to transmit the driving force. This prevents tire scuffing when going around corners and premature wear on internal axle parts. The ring and pinion set and the differential are contained within the carrier. The axle identification number is located on top of the differential carrier assembly or on a label on the bottom of the right half of differential carrier assembly. The wheel drive shafts are completely flexible assemblies consisting of inner and outer constant velocity CV joints protected by thermoplastic boots and connected by a wheel drive shaft.

How To Install Repair Replace 4x4 Front Axle Actuator Chevy Trailblazer...

If I read this correctly ( which I might not have, bit early for me ), the front drive shaft will engage ( from the transfer case ) but the front wheels are not engaged ?

If so, sounds like either the vacuum from the IWE ( Integrated Wheel End ) is not being released, or the IWEs have had an issue with part vacuum ( damage vacuum lines ) and the IWE gear is rounded off.

If you pull the vacuum lines at the IWEs ( there are 2 lines, 1 is the vacuum line, the other is the vent tube that routes up into the engine compartment and is not attached to anything ), the front wheel should engage ( might need a 5 * turn to mesh the gears ). With the vacuum lines off, jack up the front axle ( take precautions, chock the rear wheels, parking brake, jack stands, etc ) see if the front wheels are engaged ( turning one wheel should turn the other ). The option is to do this after the truck has sat over night, and the vacuum has been released out of the vacuum reservoir.

If the wheels turn correctly ( engaged ) I would think the contact plates in the transfer case are not making contact. Good starting point for this is the connector on the side of the transfer case, some times this gets gummed up, and the pins do not make good contact. The contact plates in the transfer case are used for a few things, one of them is to signal the IWE solenoids to release vacuum to the IWEs.

Operationally vacuum holds the IWE ( Integrated Wheel Ends ) out, and once vacuum is removed the spring engages the IWE.

Here is a black diagram of the IWE vacuum system

Check the transfer case. Put a jack under the rear axle and jack up the rear wheels. Have a helper put in 4 wheel and the trans in drive. Have him/her ease off the brake and see if the rear wheels spin. If they spin, 4x4 isn't working. If the truck tries to pull forward with the rear wheels up then it works. Now, if the rear wheels are spinning carefully look under the truck and see if the front driveshaft is spinning along with the rear driveshaft. If the front shaft is spinning then it is an axle problem. If the front shaft is not spinning then it is a transfer case problem. GM has a problem with the NP263 case.

Sounds like the chain in the transfer case has broke or the linkage is out of adjustment

you need to take it to a garage ,put it on a hoist , start it up ,put it in drive ,put it in 4x4 and see if front drive shaft spins,if it is and the front wheels are not it is most likely the plastic thing on the passenger side of the front axle. This is what locks in the front axle to the drive shaft. If the drive shaft isnt spinning then it is a problem with the transfer case.

your drive shaft thats turning is mabe broke or your automatic 4x4 lockers could be bad

There is a vacuum actuator mounted on the front differential that locks the shafts to engage four wheel drive.

The only Solution to this is 1 of 2 Things ! The Shifter Linkage is Off of the Transfer Case 2 The Transfer Case is Shelled out and needs to be Rebuilt. Check underneath on the Transfer case for any Noises when in 4X4 and Check the Linkages. Please Rate my Response, I need all the Help That I can Get! Thanks!

You would have to remove the vacuum lines off the motor and see if you got vacuum.