A four-wheel drive actuator is a component of your 4WD system that automatically locks hubs.When you engage your 4WD, transfer case shifts to also drive the front wheels.Once installed, this device allows you to engage or disengage 4wd feature of your vehicle. This is made possible once the central disconnect feature found in the front differential is engaged. Thanks to this feature, you'll be able to shift from two-wheel drive to four-wheel drive even while your vehicle is running.
A faulty front axle actuator will prohibit your truck from going into 4WD. One of the symptoms would be that the four wheel drive switch just flashes when trying to engage. There also may be codes stored in the transfer case control module.To test yours, simply disconnect the wiring to it and remove it from the front axle by unscrewing it. Reconnect the wiring and engage the four wheel drive, the actuator should extend. If it does not and the wiring is ok, the likely fault is the actuator.