YotaTech Forums - Problem with 4wd in 98 non-multimode tc

Ok having an issue with my 4wd on my 98 SR5 4runner. Stats: 3.4, AT, standard transfer case (no push button multi mode). Noticed a month ago when I went into 4Hi the dash light did not come on; about a month prior went a 3 day offroad trip and the system worked flawlessly. Figured it was just a burned out bulb, since I was traveling around 50-60 on fireroads and truck seemed pretty stable. This weekend in a dirt parking lot I wanted to see if the 4wd was engaging, so I put the lever in 4hi, and broke the tires loose. The person outside the car said only the rear wheels spun. I’ve read a few threads about similar problems but they usually involve the push button transfer cases and involve blinking lights, versus no light. Checked & replaced, (even though it looked good) the 20 amp fuse in slot 22 under the dash, but no change. Looking underneath the car I see the one plug that goes into the diff with the wire harness, and the two vacuum lines. Is there a way to test the switch on diff w/o removing it? Looks pretty tight. Any good next steps?
If there is a good write up on this please send it my way.
thanks Josh