service 4wd message

Hello Tahoe family, Please help. I have a 2004 Tahoe, the "Service 4WD" light came on. I checked the oil on the transfer case and it's good. Few months ago, I had the transfer case replaced due to the typical hole caused by the pump. I replaced the 4WD transfer switch and still have the warning...

Short story we needed a new encoder motor based on the fact that my Tahoe went into neutral at 65 mph's on the highway and left me with NO gears at all, not even park. This is a 2004 Tahoe Z-71 with 4wd. When hubby took the encoder motor off, for whatever reason the vehicle was not in...