Have a 98 Blazer,love it, but the four wheel drive stopped operating and now I have a 2 wheel drive station wagon....I have been a reader of your forum for a while, so I had a couple of clues as to where I should start looking.
I have a 3 button electric switch for the 4 wheel drive. Once the 4WD is engaged my front drive shaft does lock up. I hear all the normal clicks etc, Today I took my battery tray out and watched as my vaccum switch did what it is suppose to do. So now what...
I guess there is something in the front axle that is not working properly.
Could my wheel hub have something to do with it? It is starting to hum a little and I know I need to replace it soon..

Any help would be greatly appreciated.

 

*Moving to 2nd Gen Tech* - Technical questions belong in the technical areas of the forum. Gen Chat is for new member introductions only.

How much does the actuator move when the transfer case is shifted into 4HI or 4LO? It should move at least an half inch.

 

It looks like it moves at least a half inch.
It sounds like something is moving in the axle, but maybe
not enough? I'm not real sure what goes on inside there.

 

The cable pulls on the shift fork which pulls the engagement collar over the splines on the passenger side extension axle. If it doesn't pull far enough, it will not engage the splines into the collar.

There is a lot of information available via the search feature on how the front axle works. I have posted pictures of the components and there are exploded views in various threads. Maybe start by reading through the 4wd related threads in the Tech Article (DIY) section.

 

OK, well my estimation skills are not as good as I thought. I measured the movement of the cable. It looks to a bit shy of 1/2 inch. The actuator is almost flush with the metal housing of the actuator when it is engaged. Does this mean my actuator is not 'pulling' enough or do I not have enough vacum. Any help will be appreciated.

 

You can test by pulling it manually and locking it in place with a vice-grip or other suitable locking device. Just do not squash the cable too much.

 

When I had the actuator exposed, I did disconnet the cable from the actuator. It seemed to have about the same movement range as when it was connected. It looks as if the cable is not kinked in any way going to the axle. I did not see any type of adjustment either. I will try to manually pull it. Will it hurt anything to leave the axle engaged all the time? Thanks again..

 

Having it engaged all of the time will hurt your mileage, but that's about it.

 

OK, after trying the vice grip fix. I had someone else push the buttons on the switch for me. I hear the transfer case engage in 4-lo but not in 4-hi. I also hear it disengage when put back in 2-hi. After reading some posts, am I to assume that the transfer case motor is not working properly? How do I check to make sure?

Thanks again for your time....

 

Have you tried pulling codes yet?
OBD2 NV233 Diagnostics

If it doesn't go into 4HI, check out this thread:
NV233 No Mode Switch (ie. 2HI to 4HI)