Hey guys, I found out during a snow storm that my 4WD doesn't work anymore... of course it worked whenever I hit the switch accidentaly, and when I tested it a few weeks ago.. but now that theres snow on the ground and I live on a hill it decides its no good.

Anyway, would the OBS2 system work for the transfer case if I got the scanning software for my computer? Would it have stored a code? The lights flash a few times and it goes back in to 2WD.

Last year the vacuum hose fell off under the battery, but it still insisted it could engage 4WD, meaning I don't think that's the problem this time.

 

Try bypassing your vacuum solenoid actuator on your firewall! This happened to me and I did this and had 4 wheel drive until I could get the part replaced! Hope this helps!

 

I had something like this happen. Snow on the ground and no 4x4. My issue was a combination of the vacuum "switch" on the transfer case and the gearing itself for the 4x4. I had to replace the switch.... Pain in the butt if you need to lay on the ground and do it. The gearing in the front axle is not to hard and I fixed mine without replacing the gears. This video is real helpful if this is the route you need to go. Hope this helps. This also shows the vacuum "switch"

 

Thanks for the replies, I appreciate it... I tried it this morning and it didn't work so I pulled fuses 3, 5, and 19 (i think) and let it sit for 5 min, cycled the ignition 5 times (didn't start the engine, just 5 quick on and off) and now 4WD works again... of course the snows gone now.

 

I am also having a problem with my 2000 Chevy Blazer ZR2. When I press the 4 Hi button, I can hear the transfer case engage, it locks the axle for about 2 seconds, then disengages and goes back to 2 WD. I was having problems last year with it not going into 4wd and I ended up replacing the vacuum switch under the battery tray and then the switch that sits on top of the transfer case (like the picture above). 4 wd worked fine after that. Now its acting up again. I had a friend go under the truck as I press the 4 Hi, and he heard the gears engage and felt the axle lock up, but then after a couple seconds, the axle was free and the indicator switch had 2 Wd lit again. When I turn the truck on, all the lite on the switch come on (its a 3 button switch) and then just 2 wd stays lit.

 

did you pull the fuses then cycle or replaced the fuses then cycle?

 

I'm have a pain trying to get to the vacuum but on the t case cause my fuel lines are in the way. I replaced the actuator under the battery tray and the cable. Still no 4wd. 1995 Chevy blazer 2door

 

Sounds like the selector switch on the dash maybe defective.Or the vacuum switch`s on the front and rear differentials could be defective.

 

Please start a new thread and add more details on your issue.

Such as, do any of the 4wd lights on the dash light up, have you had it scanned for codes ect ect.

 

3 Button or 4, whatever your pleasure takes you there. Contact cleaner on these switches will allot of times clean up any problems the others will not fix.


Transfer Case Vacuum Switch , Diaphragm not working or cable stuck { under battery tray ) or switch on the dash.



Vacuum, Fuses may also cause this problem but will show up in the three main causes.


Good Luck