Circuit 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 Antilock Brake module. 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 de-energized 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.