Code P1870

Check Engine Soon light came on today, went to Autozone for them to read the code wich said: P1870 "Manu. Control Transmission, Transmission Mechanical Transfer Case 4x4 switch circuit failure"
Then when I got home I looked in the Haynes Manual where it said P1870 transmission slipping.
Anyone ever had this code ?
The 4x4 switch was replaced 4 months ago for the "service 4WD" message.

Bert