K 1500 Truck 4WD V6-4.3L VIN W (1997)
Transfer Case Actuator: Description and Operation
Motor/Encoder Layout
OPERATION
The Transfer Case Control Module (TCCM) operates the motor/encoder in one direction by energizing one relay while the second relay is de-energized.
The TCCM operates the motor in the reverse direction by energizing the second relay while the first relay is de-energized. The encoder part of the
motor/encoder sends shift positioning signals to the TCCM.
The motor/encoder converts a shaft position, representing a mode of range selection, into electrical signals for use by the TCCM. By interpreting the four
channels (A, B, C, D) of the encoder, the transfer case control module can detect what position the transfer case is in 2HI, 4HI, 4LO, or in transition
between any of the two.
Four hall effect sensors of the motor/encoder are used for channels (A, B, C, and D). These sensors provide a path to ground when a magnet passes over
them. A rotating magnetic ring causes the hall effect sensors voltage to drop from 5 to 0 volts. The TCCM detects the voltage of all the channels and
interprets the current transfer case shift position.
