4wd / Locker question

I have an 05 access cab 4x4, TRD off road. I have noticed lately I cannot get the locker to work. The light keeps blinking. I have tried turning it off, driving a little while in a circle, turning it back on, and all the light does is blink. When I turn it on, I put the truck in neutral, and let the clutch out in gear to try to engage it. Today, I noticed 4Lo is doing the same thing. I put it in 4 low when stopped, and the 4 lo just blinked, and beeped at me. 4 High is working fine, but for some reason 4 lo and my locker are not engaging. I dont know if somehow cold and or snow could be causing the problem or not, but it has been cold and snowy here lately. Any help would be greatly appreciated.