01 - 2hi and 4lo on 4x4 buttons are both on
 

I for sure incorrectly attempted to engage my 4x4 and now have no idea how to get my truck back to 2hi. I rarely use my 4x4, but was stuck in some deep ice/snow and went for it anyway. I had it in 2hi, and did get it into 4hi, but in trying to disengage and return to 2hi, I stuck it into 4lo. I again attempted to return to 2hi, but the 2hi buttons light just kept blinking . I was driving at the time and in hitting the buttons for them to switch, I honestly can't say what/when/how, but now both 2hi and 4lo buttons lights are on. It feels like it is still in 4lo by the way it's driving, but with both these showing as on, I can only imagine this is sending all the wrong info to the computer making my options to get into the correct gear a lot more complicated than the standard gear change steps. this just happened today during my work day, and it's about 18 degrees out and 1:01AM pac time, so I haven't done much of my own troubleshooting yet, so only the current issue is what I'm going on. only other variables are its been cold 15-20 degrees F, and before even changing my 4x4 from 2hi my service 4x4 light would periodically come on - it is for sure on now and a reminder that I told myself to not use it, and didn't take my own warning.....now I'm paying the price. any suggestions are great - and thanks for any helpful been there here's what i did's, step by step fix-it instructions or prayers / good lucks!!

We're you trying to shift while driving? I know to shift into/out of low range you need to be stopped, truck in neutral

And to go from 2hi too 4hi you can't be going very fast, like 30mph or less if I am not mistaken...

I think so, too. I always have it in neutral to shift into 4hi, as well. Just seems like it would relieve any binding in the drivetrain, if there was any

Very good point being in neutral, I forgot about that :) Shows how often I use the 4 wheel drive lol!

Here's what the 2001 Blazer Owner's Manual has to say on the subject:
Attachment 37699
Attachment 37700
There are more pages on the 4-button system after those shown above, but I didn't have time to screenshot them and get them uploaded somewhere.

Shifting the transmission into neutral can definitely help get things engaged/disengaged on an aging vehicle. Speed shouldn't matter for mode shifts (2HI to 4HI or 4HI to 2HI). Speed does matter for range shifts (LO to HI or HI to LO) as there is a gear ratio change that has to take place and the greater the speed difference between the gear sets, the greater the chance of missing the shift and potentially damaging internal components in the transfer case.

Thanks for clearing that up :) I never dreamed you could go from 2hi too 4hi at any speed... Your the man!!!

Man, even though it says that, I would be kinda leery lol. I guess as long as all four wheels were going the same speed it would be fine. Wouldn't want to engage it during "spin out"

I always do the 4lo in neutral. anytime shifting to 4hi, I usually make sure I'm not faster then 10, if not in neutral...

better safe then sorry lol

I was just pointing out the way the system was designed to function. I will say this though, if you wait to engage 4wd until you are already slipping/spinning, you've waited far too long. For me, if the roads are mostly coated in snow, I'm in 4wd. Would rather have it when I needed it than to find out I needed it and didn't have it.