i have a 2000 blazer, it has the 4 buttons on the dash with one being auto. i read another post in here that said to start the car and push the 4hi button, so i did and it just flashed ..it said when you have done that get under the drivers side and try to turn the front drive shaft, i could not turn it so i pushed the 2 hi button and tried it again and still could not turn the front drive shaft. so with the front drive shaft locked in i assume that it is a t-case problem but i dont know what to check now.. i dont have alot of money to spend on this thing so any help would be greatly appriciated..i have already fixed the oil leak and heater core problem from info from other posts, thank you for those it was a big help..

Rusty

 

The NV236 transfer case has a preloaded clutch so even in 2HI, you will not be able to turn the front driveshaft by hand.

So what seems to be your problem? What is it doing?

 

it will not go into 4wd, when i select 4hi the light just blinks, never goes solid..when i was flushing the radiator i took the battery out and checked the vacuum actuator, i pulled off the vac hose and pushed the diaphram in and held it while i placed my finger over the vac hole and the diaphram stayed put..i have not tried the vise grip thing on the cable because i wasnt able to turn the front drive shaft , so i thought i had a t-case problem..not for sure what to check next..

Rusty

 

In my 99 Blazer LS I have the same 4 button option aswell, the flashing light means the switch is engaging. If you are in park when you switch over to 4HI you might find that it will flash until you put it in Drive, if you want you can try gears 1,2,3 and see if that affects it in anyway. I found that my switch light would flash until the vehicle was in motion. If you're light is flashing 4HI and you are driving with only RWD, i would think that you're transfer case isn't engaging.

 

I recently had to work on my 1996 Blazer 4WD. I found that putting it up on 4 jack stands makes diagnosis much easier. I'm sure some would advise against this, but if you are careful and usejackstands ($20/pair at walmart)in appropriate places its really not a big deal. Put the truck up on all four jacks. Have a helper get in the vehicle, start it, put it in 4WD (not AUTO) and then shift into 1st gear (they should gently ride the brakes to prevent the tires from spinning too fast since there will be no resistance). As they do this, you get on the ground in a location where you can see the front driveshaft (coming from the transfer case to the front differential) but certainly NOT under or in front of the vehicle. If the front drive shaft turns as the rear one does, then the transfer case is fine. In this case there is likely a vacuum leak in the line going to the diaphragm (as was the case for my truck). If the front driveshaft does not turn with the regular drive shaft, then your problem is with the transfer case or its associated switches.