Review on Enhance Your Vehicle's Performance with GM Genuine Parts 89059275 Transfer Case Four Wheel Drive Actuator and Encoder Motor by Mark Bishop

This is an OEM part for the transfer case. In this app it was for a 2006 GMC Envoy AWD and fitted just right. If you have one of these vehicles, this part can fix the 4WD not working issue. I say "maybe" because this system also uses an axle position switch on the front axle, which also needs to work properly for it to shift properly. In my case, the 4x4 clicked and creaked from not fully engaging the front driveshaft. These motors have a position switch that can sometimes be replaced if the motor is still good, but my motor was pretty rusty so I replaced the whole unit. I have had no luck with aftermarket equipment for this particular part and would suggest you purchase an OEM part to fix this problem. Works great and now the 4x4 works great with no noise and fast power on. Another indicator that your 4x4 is booting up is a flashing light on the switch that doesn't change or goes out completely when you shift gears. Also check the base of the car, especially just under the driver's door on the frame, which often rusts and loses connection. There are two reasons for this place: if you live in a salt belt, cut the frame down, sand it and reinstall it with new ends and thermal tape - it could solve a lot of your problems!