I have a 1998 GMC Sierra 4x4 with a 350 and electronic shift-on-the-fly 4x4. The vehicle is currently in 2HI, but ALL of the lights for the 4x4 (2HI, 4HI, 4LO) blink very slowly and I am unable to shit out of 2HI. I can't hear the actuator, or anything for that matter, doing anything when I hit the button to shift into 4HI. I had broken the mount to the actuator and had it replaced a year or two back, but when the transfer case was nonresponsive then I had was a quickly blinking 4HI light and I could hear something happening. Any Ideas?

You need to take the box with the control buttons out of the dash...open it up and resolder the small solder joints. Or, the dealer sells them for like $65.00. Mine did the same thing and that's how I fixed it. The joints are small and crack over time. I used one of the new battery operated Coleman ColdHeat soldering guns because it has a small tip but any good low wattage gun like from RadioShack will work fine. The hard part is getting the box open, I did it and I'm all thumbs.