Chevylover2

My son drives an 01 Chevy Silverado 4x4 5.3 v8. He is currently having problems replacing the transfer case electric motor aka the encoder motor. The truck has been 2 wheel drive for 2weeks until he got the part today. How does one tell which position is which, like which is 4x4 hi, 4x4 low etc.? He already ruined the new encoder motor by turning it and he put it in anyways so now the service 4x4 light is on. Will this hurt the truck if he continues to drive it this way? He still needs to drive to college (104 miles round trip) and to work( 35 miles round trip). Any help or info is greatly appreciated.