had this problem on my 2000 silverado.

put 2 encoder motors in, a dash switch, and a transfer case ecm in, and

i found out that the ground's under the driver floor pan, on the outside of the frame, that ground the transfer case encoder motor, and the abs unit, were corroded.
this is what kept blowing fuses and eventually destroying the encoder motors.

this is a simple fix, remove grounds, clean frame down to bare metal in that spot, then re-attach ground's.
wola!!!! no more service 4wd, (provided you have a good encoder motor still)

hope this help's other people who have the same problem, i know i spent 3 hours reading post's on this issue.

enjoy!!

sy0569

 

I had this same fix poster a while ago but it was under "ABS and Parking brake light problem", I had the same problem for about a week, but my abs, 4wd, parkig brake, airbags, seat belt, every light you can imagine saying something was wrong was on, I even took it to get scanned at the dealer and they couldnt tell me what was wrong, I was actually getting ready to sell it for a ridiculous price because I cant afford to spend alot of money fixing, so one day I was like Im going to start looking for broken wires, first thing I check was the the ground wires under the drivers side cab, they were corroded to hell clean them all up and BAM no more trouble lights