99 Blazer s10 4x4 help

I have a 99 s10 blazer v6 ..4 button 4x4 automatic My problem is I'm stuck in 4 wheel drive, cannot get it back to 2wd.. the service 4x4 light is on . I removed the battery and observed the acuator while pushing the 2wd button the acuator would rease the front axle then engage ,then release, then engage it . I hear a clicking from the TCCM , the encoder motor starts to engage ,then it clicks to the 4hi button and it stays lit. Cannot get it in 4 lo either.....Any Ideas on what could be wrong

Thanks

Sounds like the encoder shifter motor. Check for troble codes..