'99 4x4 Push Button - No 4WD

[cmb23]

Winter is coming so I went to make sure the 4WD was ready for snow. Pushed the button for 4HI and it just blinked...and blinked...and blinked. Never engaged. Pushed the 2WD button and it lit up as normal. What am I looking at here???

[4x4x4doors]

Probably a loose vacuum hose somewhere between the firewall and the front axle.

[JMacEwan]

I am now having the same problem. I will look for loose vacuum lines but is there anything else to look for? Is this a common problem? My Blazer is a 2002. I am currently having electrical problems and believe I need a new switch for the inside of one of the doors that lets the system know whether the doors are open or closed. Thanks in advance for any help.

[Jim]

Had a similiar situation with my 2000 2DR LS Blazer. After quotes approaching the $1K mark I took the matter into my own hands. Turned out that the vacuum line running from the dash to the transfer case had worn through from rubbing up behind the distributor. It cost me $0.88 for a plastic union to splice into the line. That was 2 winters ago. The union shows no signs of wear, but added about a 1/2" to the length of the line and probably helped to take it off of whatever it was interfering with originally.