So my Blazer won't go into Auto 4wd, 4wd Hi, or 4wd Lo. I'm assuming the front diff won't lock, because when I stopped, put in Neutral then tried 4wd LO, the light kept flashing (as it did with Auto and Hi) but it had that sound as if it were in LO, but it still drove as in 2wd. Any suggestions as to the problem or what to check?

 

No one?

 

Check your vacuum switch under the battery. Mine did the same and replaced that and work perfectly.

 

yep looked at mine, and it was the vacuum hose that ran by the side of the exhaust manifold. hope that helps

Matt

 

it could be the thing under your batt or the vacume accuater on the t case 20 dollor fix

 

While on the topic, My brother's 2000 ZR2 Sonoma has an issue where the hose that actuates the diaphragm under the battery draws no vacuum. Any idea what could cause this?

 

The line that goes to the accuator did you follow it back and see if it is all intact or if there are any breaks or cracks or holes in it?

Matt

 

It is fine on my brothers.

 

mine is doing the same thing now and i have to replace the transfer case

 

I doubt your transfer case needs to be replaced. But if you want to discuss this further, we can do so in a new thread.