My 2005 Blazer ZR2 wont engage into 4wheel

It will go into 2wd and 4lo. Common sign of encoder motor (shift motor) failure. It cant sense where it is in the shift so it can only do the extremes. For laughs listen for the shift into 4hi and pull the fuse. Plug it back in and see what light lights up on the switch.

Same happened to my step moms jimmy. Andrew is correct, and if you don't have much money, because its quite expensive, get a $20 repair manual and go to the vineyard and pick up a used one.

Thanks for you help, however, I took out the battery, had a look at the actuator(??) and pushed in the rubber a few times to make the cable work. I could hear it clicking down below. I tried looking for vacuums hoses, but couldn't find any. All that took me about 15min to take out and put back the battery, looking, etc... Once I had the battery back in place, I turned the vehicle on, and TaDaaaa, it worked!!! I read a few other remarks and some say to just disconnect battery for 10 min or so. It resets the computer. If anyone is having this problem, do that first. Always start with the simple tasks first. :)

Hate to burst your bubble but that is a quick fix. You will probably find in a week or so you will have the problem back again. Might want to just leave the TCCM fuse out until you need it, then it should give you a few proper engagements before it fails again. This is due to the way the TCCM works, it takes a few "failures" before it registers a problem. Then it will be back to it's old self. Wish you luck, maybe you'll get lucky.

Ding ding ding what do we have for him johnny?

How about this, I have a 2004 ZR2 blazer that may have a auto transfer case with no auto 4WD button inside and I think it may be in 4WD all the time, still figuring it out.