2000LiftedZ71

Hey guys I am in desperate need of help! Ok, so my truck is a 2000 silverado z71 4x4 with the push button switch on the dash. A few months ago, my transfer case went out and I got a replacement from a junkyard. They said that they checked the inside of it and that it was mechanically sound ( I believe they actually do check it because they warranty it for 6 months ). After installing the new transfer case, if I select any of the 4wd options, I can hear the front actuator engage loud and clear (its brand new). But only the rear wheels get power. So, I jacked the truck up and put on jackstands to try the 4wd out, and all tires spin!!! But any resistance/load at all and they lose power, which explains why they don’t get power on the ground. If I put my ear really close to the encoder motor, I can hear it click and engage. Is it supposed to be louder than that? If not, any input is greatly appreciated!!!!!

tech2

disconnect the encoder motor electrical connector, then remove it from the tcase. put a wrench on the stub that the encoder turns....turn it manually into 4high...test drive to see if it operates in 4wd...if it works by manually shifting...the encoder motor is weak. if you have your old encoder motor..install it.