Hey there I am new to the site, I just bought my self a 2000 Blazer Zr2 with 232000 kms on it and my 4x4 is not working I here the electric motor in my transfer-case working but my front diff is not kicking in and turning the front wheels, I am not sure what is wrong I was told it could be an assortment of things from my 4x4 switch, modulator, wiring, electric motor, can anyone give my any advice on what to look into to first? because when the truck is in 2hi the light on the switch is not on, and when I go to put it into 4hi I here the little motor engage but the light in the switch flashes and the front wheels do not turn, It does the same thing for 4Lo as well. Has anyone else had this problem? If you know what it is can you let me know it would greatly be appreciated. Thanks

 

Check out the DIY section, there's a great write up on 4x4 diagnosis.

 

Does the 4 button switch on the dash successfully stay lit in 4 HI, or just blinks, then goes back to 2 HI?

If it blinks, then goes back to 2HI, then it never really went into 4WD, I just wanted to clarify that. In either case I would check the vacuum hoses first because they are the easiest to check. The vacuum hoses are about 1/4 inch in diameter and run mainly from the center of the firewall up near the dash inside the engine compartment to an area underneath the battery. You may have a crack somewhere along the line. If there are any leaks it will not go into 4WD.

There are also some lines that run along the fuse box (driver's side) that you may want to check too. If you do replace some make sure you get enough to replace anything over there too.

Once you check all the lines and replace whatever is needed I would even remove the battery and the battery tray and check out the diaphram under there, make sure that the hose is secured to it and didn't slip off or get cracked. While you have the battery tray off check to make sure that the diaphram isn't cracked itself and make sure the cable and diaphram have some movement.

 

It stays in 4hi and just flashes I here the electric motor on the side of the transfer case kick in but front wheels don't turn, Thanks a bunch for the information I will most definitely take a look at all of those lines.