All lights on my 4wd selector switch stay on on 1999 Chevrolet Blazer

All lights on my 4wd selector switch stay on. Last week I heard a bunch of clicking coming from the passenger side lower dash area. Since then the clicking has stopped. All the lights remain on and don't appear to do anything when I hit them. However I got in the truck this morning and when I took of as I went from first to second gear it felt like I was going over a rumble strip and the tach dropped down to 1000 rpm. I gave it some more gas and it accelerated normally above that gear. Any ideas. Fluid level is good and Trans fluid is clean and smells as it should.

Asked by for the 1999 Chevrolet Blazer
Have the transfer case module scan tested, should have trouble codes!
Ok, I will try and get that done today.
1 more answer
My car is doing the same thing what was the issue to fix it please