Vacuum Systems

When the Four-Wheel Drive shifter is moved to a four-wheel range, a shift mechanism in the transfer case closes the Transfer Case Vacuum Switch. Closing this switch applies vacuum to the vacuum actuator. The vacuum actuator pulls a cable, which pulls the shift fork in the front axle. This connects the axle output shaft to the front axle differential to apply torque at the front wheels.

Moving the shifter to the two-wheel range causes the vacuum switch to open to the vent position and the actuator releases the cable to the shift fork in the front axle. This returns the operation to the two-wheel drive position.