K 3500 Truck 4WD V8-393 6.5L DSL Turbo VIN S (1995)
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.