Service 4WD and 4WD INOP (already checked threads)

[WILBGLC]

I have a 2000 Chevy Taho 5.3 with Electronic 4WD.  The 4WD stopped working and the dash displays "Service 4WD".  The actuator on the front diff is engaged and I swapped it with another good one that is disengaged and it stays disengaged.(if I remove the fuse under the hood I can hear the actuator disengage but when I put fuse back in I hear the actuator engage again)  (The lights on the switch flash real quick too when I install the fuse and turn the key on.)  Here is what I have done so far.  Checked fuse on side of dash and under hood and both good.  Removed and cleaned grounds under drivers side door.(still nothing)  Replaced switch on dash, still nothing (no lights on switch either).  Replaced transfer case motor with a new one and still nothing.  Swapped 2 different(working) modules into truck and still nothing.  I have disconnected battery and held pos/neg terminals together for 1 minute and reconnected everything, still nothing.  I have poured through countless forums including this one and have tried everything suggested except electrical testing of components (ohms, etc).  The reason I chose not to test is because I am using(swapping in) known good components.  I suspect a bad ground somewhere even though I have cleaned and reinstalled the 2 known grounds.  How should I proceed with this?  I am very frustrated.  I also am tempted to manually switch transfer case into 4 high and install a manual switch to operate front diff actuator( I understand that using AUTO 4WD works the same way by keeping t-case in 4H and engaging-dis-engaging the front diff?).  PLEASE HELP  and THANK YOU!!!

[swathdiver]

You need a Tech-2 or equivalent to tell you the internal codes as to why it's not working.  Even if you swap a module out, you must perform a relearn or it likely won't work.