2004 Chevy Avalanche switching into 4 high

Upon switching into 4 high the light blinks and a message appears stating 4 wheel drive needs servicing.

i go into 4 wheel drive 6 times a year.

I put a code reader on the port and no errors were shown.i then tried to switch into 4 h with code reader pluged in.still no code.

im able to select 4 low and it goes in and light stays steady.but the 4 high still blinks.

note the lights are on the selector switch.a solid green mean its engaged into 4 wheel drive.

thanks for the time