1992 S-10 Blazer 4x4's TCCM & Encoder motor issues.

As often happens, I have 2 customers with near Identical Vehicals with Simmular problems.
Truck #1: CPI (Vortech style) 4.3/Automatic.
No power at TCCM (Transfercase control module) Power Key ON at TCCM Fuse. Transfercase in High Range, Front axle unlocked.
Truck #2: TBI (Pre 1992 Style)4.3/Automatic No Power at TCCM Power Key On at TCCM Fuse Front axle locked in for 4WD/ Will not unlock unless Vaccume line is removed from Vaccume Servo (under battery tray). When left with Engine running, Transmission in Park, Vaccume line on Servo, can hear encoder motor trying to switch something.
    My time to diagnose both vehicles is limited at current. At current I don't have a decent manuial covering these transfer cases, controls and trouble shooting proceedures.
    Any one have any good advice? Charles
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