Can the four wheel drive actuator freeze up and cause the four wheel drive to not engage ?

Remove the actuator motor assembly from the transfer case and try to manually engage the transfer case, if it is easy to engage then the actuator is the problem.

Four wheel drive actuator may me at fault, try park the truck on a slick surface like wet grass, set it in neutral and activate 4hi and 4lo back to 2wd a few times, if doesn't help try tapping on motor actuator located on transfer case while someone activates selector, park surface must be as level as possible, a good tip is to activate your four wheel drive once every few months to avoid it freezing up.If nothing helps then it needs to be diagnos by a tech. good luck

There are 2 models here the push button will flash if the system is not engaging or disengaging properly . If front drive shaft is turning. That is with car raised and supported . if front drive axles do not turn then the axle actuator is not engaging axle shaft passenger side. Remove actuator and manually engage shifting collar with a screwdriver still does not turn then inner axle is twisted.

you probably need to put a new actuator in it

This could be defective 4X4 actuator motor or jammed transfer case. Has the fluid ever been changed in the transfer case? if not that can cause the case to jam and not engage.

It's most likely the "four wheel drive actuator" This is located on the front differential housing. It's cylindrical shaped and has a large hex (about
1-1/4") and two wires coming out of it. Usually they short out and blow the fuse but, I've also seen where they just quit working and sometimes they just get slow to work. The "actuator" has a heating element in it and it warms up, some sort gas, causing it to expand thus engaging the front wheels. In cold weather it may take a minute or so for it to engage, so put in four wheel drive and wait for a bit and see what happens.

You probably have a bad encoder motor.It is located on the side of the transfer case on the drivers side.It is black.The other problem they had with these was the switch but you have already replaced this so your next thing is the encoder motor.Hope this helps.Good luck.

There is a solenoid (popper thingy) that engages your four wheel drive. It is bad, it costs around eighty bucks, but is easy to fix. Go underneath your truck and look at your transfer case, it should have a wire or two going to it, that wire connects to the solenoid. Remove the solenoid, put the new one in and your light, and your four wheel drive will work again. This is a common problem with that type of four wheel drive system in the year ranges of 88-97.

If you have push button 4-Wheel Drive, it is recommended that you use it every once in a while, in order to keep gunk, rust, and corrosion to build up on moving parts. The mostly likeley (though not definite) reason would be that you let the 4-wheel drive unused for so long that corrosion has built up on the parts and the actuator that engages the 4-Wheel Drive doesn't have the power to engage it past the corrosion. You'll need to take it in to be cleaned, or to have parts replaced. In the future, every month or so, engage 4-Wheel Drive and drive around in some mud, grass, sand, or any other loose ground for a bit, just to keep the parts moving and clean.

The service Four wheel drive light is to alert the operator the system is not being read properly by the ECU.

If the ECU loses contact with or position of the Transfer case actuator motor the service light will come on. Same thing goes for the front diff actuator.

So it may be a bad switch, sensor, or an actual problem in the 4WD linkage. This is not a Oil Change light that you can ignore a few extra weeks - it indicates a problem that should be taken care of ASAP to avoid costlier problems down the road.
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w9fro..In1995, and other model years, the actuator used to engage the transfer case into four wheel drive is oil filled with a heating element.
When you select four wheel drive the element heats up, the oil expands and engages the transfer case. Unfortunately if the actuator fails, the truck remains in four wheel drive. GM has an improved actuator so the problem does not repeat.
As always, check the basics, power, grounds and switch at floor select before replacing the actuator.
Also, if the truck is truly stuck in four wheel drive, you can tell by turning the truck in a tight circle. If the front end wants to "bunny hop" it is definitely engaged.
Best of luck, let me know.
Regards,