Theory Of Operation

Front Axle Disconnect (FAD) Actuator 

When the vehicle is in 2WD, the FAD system prevents the front axle ring gear, pinion gear, front drive shaft, and the front drive components in the transfer case from spinning. This allows for better fuel economy and reduced wear of the Front Axle and Transfer Case components. There are four circuits between the FAD Actuator and the Drivetrain Control Module (DTCM):

• Fused Ignition
• Front Axle Lock control
• Front Axle Lock Signal
• Ground

When 4WD is requested, the DTCM grounds the Front Axle Lock control circuit. This causes the actuator to move a fork that slides a sleeve over the right axle shaft and a stub axle shaft linking them together. The FAD Actuator sends a signal back to the DTCM to indicate the fork position.