2008 Dodge Ram 1500 - How do I check the drive selector?

have a 2008 dodge ram, 4wd switch flashes all the time even when I have it set on 2wd. when set on 2wd front end is locked in but not transfer case. when I turn selector to 4wd transfer won’t lock in , seems to me the selector could be faulty. not sure how to test?

It’s electronic control, then a simple voltage test at the actuators will tell you if the mode is being properly commanded by the selector and it’s a bad actuator or something more involved…

I have run my truck for about two years without cv axles, now I have replaced front cv axles . truck won’t engage in 4 wheel . I have noticed front end is already locked in but the transfer case is not. Service 4wd light is on. I have read somewhere that the actuator and shift motor could be out of sync. How does one get them back in sync?