Light just came on. 4wd works but the switch will not light up another selection when i go to it. If i turn the car off then back on, the light goes off and i can change it then. The light will come back on, but the 4wd works. Any ideas? Maybe change the fluid or its low?

When it changes from 2wd to 4hi and 4 lo, the motor (im assuming) is loud and you can feel it shift into 4wd.