96 K2500 4x4 not working

I have a 1996 K2500 suburban. when I got it the 4x4 was not working. the previous owner had it in the shop and they told him it was the motor on the transfer case (this is push button auto). when I got it the 4x4 fuse was blown. I put in a new fuse and it blows as soon as I press the 4 high button. I took the wires off the motor and the fuse wont blow.
I went and spent $160 and bought a new motor unit then laid out side in the snow to change it. but when I hooked it all up it still blows the 4x4 fuse as soon as I press the 4 high button. whats wrong. where should I be looking. I have the autopsy from the local dealer who diagnosed the problem for the previous owner.

Joe: Need to know if the fuse that's blowing is the "T Case" fuse or the "4wd" fuse? And do you have the "AUTO 4WD" function on your switch panel? Let me know and I'll try to help more. Keep in mind I'm looking at a '98 service manual.

its the transfer case fuse thats blowing .I dont have the auto function. my choices are 2wd 4 high 4 low. this suburban was factory made with a small block 400 and a heavy duity tow pack and stage 2 trans kit. a 24 volt alternator and twin batteries.

The T Case fuse feeds directly into the Transfer Case Control Module (TCCM). When you select 4wd that power goes out from the TCCM to the Encoder/Motor on the t-case. So, I'm thinking an internal failure to ground in the TCCM or a direct short to ground on one of the feed wires from the TCCM to the Encoder/Motor. My '98 K2500 7.4 was blowing the t-case fuse just driving around. Drove me nuts. Finally found a worn wire behind the right side of the engine block shorting out. By the way the T Case fuse is Hot at all times. Good luck.......Steve