First hello. Im Mike. I have a 99 CCSB k2500 with a 5.7 4l80e w/276k miles and the three button 4x4 (2hi 4hi 4lo). Im in the middle of rehabbing my poor beast. Its been worked hard and neglected for awhile and Im bringing it back slowly. The front end was just completely rebuilt with all new steering bits, gearbox, shocks, and BJs. Need a new rag joint and the steering will be slop free. New stainless exhaust, and new bumpers. Theyre stock but the rear was being held together by the chrome. Complete brake job, lines, calipers, rotors, cylinders, drums. New front and rear bearings. I need to do a little body work on the driver cab corner and Im gonna put a new box on the back. It was a northern truck for the first 6 years of its life so it has a little rust issue. Eventually it will get a 4 to 6" lift 35s and a new gunmetal grey paint job. So anyway the 4x system is next. Ive been reading through the forum trying to fix my problem and have seen mention of a troubleshooting .pdf for the three button 4x. I have been trying to find the .pdf for the electronic shift 4x but none of the links here seem to work. So I figured I would just ask. So heres the deal. My 4x system isnt working quite right. I can shift from 2hi into 4lo and back by putting the trans in neutral like youre supposed to. When I do both the 4hi and 4lo lights come on. When I shift back to 2 hi the lights stay on. 4lo works fine as does 2hi. The problem is that the truck will not shift into 4hi. Ive tried from 2hi both sitting still and moving and from 4lo stopped neither will work. Ive pulled the tccm and switch and cleaned the contacts and coated them with dielectric. Obviously the diff actuator works or 4lo wouldnt. Im not sure about the tcase in this setup. Does the front drive shaft in these systems always get power from the tcase and the diff actuator just engages the diff? Or does the tcase disengage the front shaft as well? I know in older trucks the tcase would disengage the front shaft but Ive never had to tear into a newer one. Thanks in advance and Im really looking forward to getting this fixed. Once everythings done Ill throw up some pics in the 8 lug thread.