Affordable transfer case encoder motors can be found here: https://amzn.to/2Bsk0Wo
Repair your malfunctioning four wheel drive by replacing your encoder motor. If your vehicle won’t switch in or our of 4WD, but you can hear the transfer case trying to switch, you may have a bad (or weak) transfer case encoder motor. The vehicle in this video is a 2000 Chevy Blazer, but the encoder motor replacement procedure will be the same, or similar on many other vehicles. GMC, Chevy, Oldsmobile Bravada S10 Jimmy and many other GMC trucks and SUVs
Affordable transfer case encoder motors can be found here: https://amzn.to/2Bsk0Wo