I just bought a new GMC 4x4 and have some questions about the shifting in and out 4 wheel drive. This is my first 4x4. Manual says i can shift "on the fly". (floor mounted transfer case). i can shift from 2 wheel to 4 wheel HI from a dead stop,but can't always shift while moving anywhere from 10 to 30 miles a hour till,what seems the truck warms up some. Temps. here in Massachusetts has been around 10-20 deg. range. After truck warms up some,shifting seems to be o.k. I guess i expected to be able to shift in and out of 4 wheel drive at any speed and temp. I think its my misunderstanding of the conditions for shifting,and not a problem with the truck. 4 wheel "low" works as advertized. Thanks

:( I have a 94 Sonoma SLE 4x4 with electronic 4x4 shift. Lately, and quite consistantly, when I take off in two wheel drive I can hear only what I can describe as a buzzing/light growling noise coming from the front end, seems to be more to the passenger side, and it builds up in pitch as I accelerate, which I am sure is gear train buildup of some sort. Then, as I slow to a stop, and am down around 3 or 4 mph, there is quite a pronounced bang/clunk like the pressure releasing, and it appears to clear up, but on reaccelerating again, the problem returns. Lately this is happening more often than not. I replaced the push button switch module, which wasn`t working properly, but this problem persists. Can someone please help me out with this, thanks. Frank.