the transfer case motor has to be replaced
4 wheel drive module located in the passenger side kick panel. Most likely condensation got in the plug. About 450.00 to replace it at a dealer! Checked on 7/27/07.
It could be the shift motor on the T Case. Or it could be the automatic shift button switch on the dash.
If the button is not working, might be a vacuum line problem. Vacuum lines engage the 4x4, might need to check the lines to the 4x4 transfer case.
The 4wd in the 1999 Chevy blazer is electronic, you just have to push the button. If you have pushed the button and it doesn't engage, it might be a vacuum line. The lines are made of rubber and over time they melt. It costs about $25 for a new metal line. Also, the 4wd is under the battery. If you take the battery out, you might notice that a line got disconnected accidentally.
The starter drive, also sometimes called the bendix, needs to be replaced.
Probably low on freon.
check the vacume lines that go to the front dif
This has a vaccum operated servo; you probably have a vaccum line that has come off to the transfer case.
transmission won't engage when you push the button on john deer 155c automatic
sounds to me like your front end is not disengaging, bad actuator under battery.
check vaccuum lines on cruise control and other things that use vac
To engage the 4x4 manually (VTM-4), you would need to be in 1st, 2nd, or reverse gear. In those gears and while stopped, you can then press the VTM-4 button, and will engage 4x4. It will only be engaged when around 18mph or lower. Above that, and it will disengage. It will re-engage when it dips down to that speed again. To turn it off, you can just press the button, or shift to a higher gear Keep in mind that even with the button off, VTM-4 will engage occasionally when there's slippage.