1999 GMC 4wd stuck?

[JRDNORTAX]

1999 GMC 2500 pickup w/ pushbutton 4wd. The transfer case seems to be stuck in 4wd(you can't turn the front driveshaft by hand when it is in 2wd, even with the CV shafts removed) It made some noise with the shafts installed when running, and we took out the cv shafts and it doesn't make any noise. We can hear the motor on the transfer case work, and the dash lights for the 4wd seem to work OK. The "Service 4wd light" comes on and goes out on it's own. Had it on a OBD tester and it didn't show any codes. Any suggestions on what's going on?

[kiyak]

Have same problem with 99 GMC can't find any info for correcting problem,did not have any warning codes on panel info center, only great reduction in gas mileage for many thousands of miles before finding problem. Appreciate any info for correcting malfunction,also will post anything I can find.([email protected])
2/4/06........GM serviceman informed me that 99 GMC 4x4 front drive shaft turns
continuosly.(electric shift model)