new everything still no 4x4 consistent operation

[rural701]

2001 ranger 4x4 4.0 live axle auto. When I unhook battery and then reconnect,4x4 works and will work consistently until I turn the truck off and let it set(overnight). Then no 4x4. When it works the instrument cluster 4x4 lights come on at startup as normal. They work when 4x4 switch is moved to 4x4. When let set over night the 4x4 cluster lights do not come on at startup.4x4 does not work. History: replaced GEM-behind radio, new 4x4 control module in right kick panel, and new transfer motor. No change. It is snowing and this is my mail route truck. HELP