2wd light blinks then defaults back to 4wd

[Zach Craw]

Truck is stuck in 4wd if you press the 2hi button it will flash then default itself back to 4hi no service messages and no codes in the system there was a history code for u1026 but battery died while diagnosing and now I have no codes I tried a new atc module and scan tool says no communication if you put the old module back in it has communication again so I tried another module thinking I had a bad one and sure enough no communication again I tested wiring back from front axle everything was good I tested wiring back from transfer case actuator and that was good as well don’t know my next move also truck is 2005 1500 

Edited October 12, 2021 by Zach Craw