93 Blazer 4 wheel drive problem

Ok.. Went to use my 4x4 the other day when we got a little snow and the light comes on on the switch when in 4 high and I can hear it engage at the transfer case. Well the truck felt a little squirrely so I knew something wasn't right. First thing that I checked was vacuum lines because I know that is a big problem on these things. Everything looked fine so next I pulled the vacuum line that goes to the transfer case and put in to the PCV valve with the engine running and the front differential engaged. Well since it engaged I said to myself, replace the transfer case vacuum switch. I replaced the switch and still no 4x4. Any help or suggestions would be greatly appreciated. I would like to fix it before the snow that is supposed to be arriving.
Thanks
Mike

Ok.. Went to use my 4x4 the other day when we got a little snow and the light comes on on the switch when in 4 high and I can hear it engage at the transfer case. Well the truck felt a little squirrely so I knew something wasn't right. First thing that I checked was vacuum lines because I know that is a big problem on these things. Everything looked fine so next I pulled the vacuum line that goes to the transfer case and put in to the PCV valve with the engine running and the front differential engaged. Well since it engaged I said to myself, replace the transfer case vacuum switch. I replaced the switch and still no 4x4. Any help or suggestions would be greatly appreciated. I would like to fix it before the snow that is supposed to be arriving.
Thanks
Mike


If it will shift when you tap it onto the pcv valve line it sounds like it is not getting good engine vacuum where the transfer case line hooks to engine vacuum.
Get a vacuum gauge and check it for good vacuum there.

Ok.. Here is what I just did. I went under the truck and checked to see if it is getting vacuum at the switch on the transfer case. One of the ports I can feel a sucking and the other two I don't feel it. It will shift into 4 low if that makes a difference. I will check back later tonight for any replies. Thank you in advance- Mike

Ok.. Here is what I just did. I went under the truck and checked to see if it is getting vacuum at the switch on the transfer case. One of the ports I can feel a sucking and the other two I don't feel it. It will shift into 4 low if that makes a difference. I will check back later tonight for any replies. Thank you in advance- Mike

If you have vacuum at the switch see if it is going threw the switch.

If you have vacume with one line, then thats good, one line supplies vacume one is a vent and the 3rd is the line to the front actuator under the battery. Check vac to the actuator and besure the unit it self is in good shape and that the cable is not broke/binding anywhere.

Good News! It's all fixed. Looked around some more and found a vacuum line with a big hole in it. Tee'd in some new hose and 4x4 works better than ever. Just in time too; as the nasty wintry mix attacked tonight and I was able to make it home from work safe and sound. Thanks for the help. Mike

Thanks for posting the fix and letting us all know how it went.
Glad all is well and just in time to.:grinyes:
MT