Toyota Repair: Blinking 4WD Light on my 2001 Tacoma, sandy road, wiring harnes

Question
I purchased a used 2001 Tacoma 4WD 4Door with an automatic transmission with 71K miles and at least 1 previous accident before I owned the truck.  Recently I had the opportunity to 'excercise' my 4WD on a sandy road and in the mud.  I pressed the 4WD button and the truck immediately engaged the 4WD.  On my way back I pressed the button to disengage the 4WD and heard the click of the front transfer case disengage but the green 4WD idiot light is now flashing.  It won't go into 4WD or come out.  I am pretty mechanically savvy and can fix almost anything.  I checked the wiring harnes to what I believe is the ADD and all seems well.  I checked the vaccum line which runs to a one way vent with no clogs and still nothing.  Please help and give me some ideas for diagnosis or fix.

Answer
Well its either in  or its out.
Try putting it in reverse and goose the gas.
Sometimes the ADD stays engaged,
There is a switch on the transfer that lights the light that may stick.
You can watch the tranfer operation in PARK while someone hits the button to see if its moving the acuator.
You can get the whole repair manual at www.techinfo.toyota.com