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 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.