My 4 wheel drive indicator lights just flash when trying to shift out of 2HI

My 4 wheel drive indicator lights just flash when trying to shift out of 2HI into 4LO, 2LO or Auto 4 wheel Drive. The lights will continue to flash until I push the 2HI button, then the flashing lights stop and the 2HI light is on. I usually can hear a noise at the rear of the car and I notice the RPM gauge reads higher at the same speed while the lights are flashing. I do know the front tires are not engaged, because I viewed them while I was stuck and the 4 wheel light was flashing. I know I must have the transmission in neutral to shift to 4LO. The blazer was not used for about 2 weeks just before this problem started, also the check engine light came on after the idle period for about 2 weeks and then one day when I stated it and it was off. I have checked the transfer case and the panel light fuses.