The 4WD transfer case attaches to your trucks transmission and allows you to easily change between rear-wheel drive and four wheel drive, 4x4. The transfer case consists of a series of gears and chains and when switched over allows power to be transferred to the front wheels and rear wheels at the same time. In order for the transfer case to switch into four wheel drive, 4x4 mode a gear must be turned inside the transfer case.
The 4WD Transfer Case Shift Encoder motor is the part that turns the gear inside the transfer case, allowing your vehicle to be switched into 4x4 mode. The Shift Encoder Motor is located on the outside of the transfer case and is secured to the transfer case with 3 bolts. If your truck will not switch into 4x4 mode a faulty Shift Encoder motor maybe the cause.