I have a 99 Blazer, 4door, LT..

my son took his family to the lake today, down on to the beach, as he has done in the past.. when he goes to turn around, he goes into 4HI, to not get stuck... worked well in the past...

this time, all his 4WD lights went out (no button will light up), (the service 4wd came on, but went out again), and he also now has NO gears at all... shifting to any gear is like shifting to Neutral.. shifting BACK to park makes a short grinding sound...

Now, we did try some things.. disconnected the battery for 30 minutes to reset.. nothing.. I checked all the fuses, inside and under the hood, they're fine.. I also pulled out the kicker wall on the passenger side and checked the TCCM connection, they look ok also..

Any suggestions? NOTE: his transmission fluid DID need filling.. but, there are no check engine lights coming on, or anything of that nature

Is there anything I can check without major tools? I'm not a mechanic, and neither is he..

now, to add to this, the vehicle is currently being worked on for a heater/AC problem.. the heat is not hot, the AC is not cold. we're waiting for a temperature sensor (module) to be installed this week... since this also runs on the same vacuum system as the 4WD, is there a possible connection?

 

Sounds like the transfer case (NP236/NV236 from the 'service 4wd' note) is stuck in neutral. If you have no power getting to the TCCM, then you have to fix that issue...