Will not shift past second and will only go into second manually. Happened after a long drive. Also stuck in 4-lo. It drove decently for about 60 miles after sitting a while and once it got to temp, the transmission started acting up. After letting it cool down over night, I drove about 25 more miles before the same symptoms occurred again. Any insight would be helpful. Worried its a shift solenoid or torque converter.

 

Did you drive it in 4-lo for 60 miles? At what speeds?

As for the trans not shifting into third, that could be due to a damaged 3/4 clutch pack. This will occur when the transmission gets overheated. I damaged mine by towing my boat over long distances while in overdrive.

Loom up "common failures or issues with 4L60E" online to learn more.

Have you gotten the transfer case out of 4-lo?

Do you have the 3-button or 4-button transfer case? The 4-button one has the Auto-4wd option.

 

You may get lucky with tranny and its only the trany solinoid pack. However christine_208 is probably correct and needs trany rebuilt. If you get transmission rebuilt, you will be a another member of the transmission worth more than vehicle club.
Factory 4L60's are a compromised unit, if U get 100,000 miles your on borrowed time... If you decide to go rebuild route have conversation with shop as there are a bunch of hardware updates that make transmission bulletproof. Probably about $300 to $500 bucks for all the updated parts.
Automatic transmission and transfer case have separate controls.
Transfer case stuck in low range is not related to transmission.
Check dash buttons for function and transfer case controller relay located forward of passenger door behind kick panel.

 

I was well aware of that when I had mine rebuilt!

Then again, I'd argue that even with the price of a rebuilt transmission, a Blazer still can be less expensive than replacement truck you can trust.