I've already tried to search the forms for a solution, heres my problem: I got a 02 blazer 2 door 4x4 v6, When I try to put it in 4 hi all i get is the 4hi light flashing, when i try and put it in 4lo the light flashes and I hear something like it engaging from the floor board and when i give it gas it feels as if its shifted into 4 wheel but i get no spin from the front tires and the 4lo light just flashes. I checked the vacuum acctuator under the battery already and everything appered fine. Any help would be good, I'm not to familar with this vehicle its a friends.

 

I would start by going through THIS THREAD if you do not have the Auto4wd option.

 

I have auto 4 wheel, with the 4 button option. Also I have checked the front drive shaft and it is moving once i hit the 4lo button but the front tires are not spinning

 

If that is the case, then you have a vacuum supply problem to the front axle. I would start at the actuator (under the battery tray) and check for vacuum at the actuator. Then I believe there is a solenoid valve or sensor up on the firewall that should have some wires and two vacuum tubes running to it. You can check for vacuum there as well. The one vacuum line runs back down to the vacuum switch on the transfer case. The switch has been known to be an issue for quite a few people. But check for vacuum at each of these locations in that order.

 

So how am I gonna check for vaccum?

 

If you do not have a gauge, you can simply remove the hose and if you hear it sucking air in, you have vacuum. The engine will need to be running inorder to test. You will have to have the 4wd engaged as well.

 

Hey thanks man, it turns out there was a hose cut up by the firewall, replaced that and it works awesome now.