K 1500 Suburban 4WD V8-5.7L VIN R (1997)
Four Wheel Drive Indicator Lamp: Description and Operation
When the Ignition Switch is in "RUN" and the Four-Wheel Drive Control Lever is engaged, the Transfer Case Switch closes and Battery Voltage is
supplied across the Front Axle actuator. The Front Axle actuator energizes and the Four-Wheel Drive gears are meshed. This meshing action of the
Four-Wheel Drive gears closes the Front Axle Switch, and Battery Voltage is supplied through CKT 1695 across the Four-Wheel Drive indicator,
lighting the bulb.
Battery Voltage is also supplied through the Front Axle Switch contacts and CKT 1695 to the Rear-Wheel or Four-Wheel Electronic Brake Control
Module (EBCM). This will modify the Antilock Braking System operation in 4WD mode.
A Transfer Case Relay is used on one-ton vehicles with Four-Wheel Drive. This relay is deenergized when the vehicle is in 4WD mode. From the
Transfer Case relay, Voltage is supplied to the Transfer Case synchronizer until 4WD mode is selected.
