Met up today with ...Retired BLM Rig. Big thanks go out as he spent an hour+ with scanner and looking at other things.
He has a SnapOn scanner that can read serv4wd codes. Scanner was able to detect a bunch of past codes relating to anything but the serv system. Was only able to establish "no communication" with my issue. Scanner mentioned TCCM (transfer case control module) and CTM (central timer module) no comms. Several attempts were made but just couldn't get in.
Also checked fuses, under dash connector and smart bar connector.
My issues are intermittent ....I tested f+r lockers and both worked 30 minutes before he arrived. Serv light was off. Next try, rear worked and not front...and then neither worked (serv light on).
Next up I will check all grounds. Under hood has about 5-6 scattered around , and find out more about TCCM and CTM.
My opinion: There is WAY too much electronics involved in getting these lockers to lock.

A couple of switches with some warning lights would have done the same thing.
