Isuzu 2000 Trooper Workshop Manual page 357

Normal Operation
The motor actuator mounted on transfer rear case is
driven by signal from 4WD switch on instrument panel.
After complete the connecting transfer front output gear
to, or disconnecting it from, front propeller shaft, condition
Time Chart of Shifting Under Normal Condition
DRIVE LINE CONTROL SYSTEM (SHIFT ON THE FLY)
of the transfer position switch changes. The vacuum
solenoid valve (VSV) is driven by the signal from transfer
position switch and the vacuum actuator connects front
wheels to, or disconnect them from, front axles.
4B1–3
F04RW002