Can anyone help? H I am having trouble with my 2000 blazers engageing the front wheel drive. Took off the Vacum accentuator under the battery It seems to be in good conditon. I noticed that wheni manually depressionthe acentuator I heard a vacum leak somewhere at the top of the engine where the vacum hoses connect?
any sugestions?

 

Any easy way to check some of the vacuum lines is to see where your interior fan blows.If it only blows through the middle vent then the vacuum line from the cannister is likely disconnected. This was cause the front wheels not to engage in 4WD but will show on the 4wd light lit solid when selected.

 

without proper vacuum your vacuum actuator will not properly engage.

I would recomend you find the vacuum leak.
If this occurs frequently and your 4x4 is a regular critical function, you might want to look into a manual cable system.

 

easiest way to verify that all 3 lines for the 4WD system are connected & in good condition, is start with the vacuum switch on the t-case, and follow where all 3 of the lines run to, making sure nothing is apart or cut.

also make sure that the hose itself is in good condition, and not super soft or full of cracks.

 

Ok I checked the fan! Air is blowing through all vents. Also followed babum lines. They appear to be connected and in good condition. I then put the vehicle on jack stands. I went under the car while my wife engaged the push button switches. I could hear the system clunk when the button was pushed. However only the passenger wheel would turn in drive not any front wheel. I also noted that front drive shaft was not turning. Should that turn when the push button is pressed or does that turn in response to the front wheels engage? Thank you all for your responses they are extremely helpful.

 

If your front driveshaft didn't turn, then the transfer case is not properly engaging.

How many buttons are there on the 4wd switch?

 

Hello there are 4 buttons. A. AWD b. 2WD C. 4WHi, D. 4WLO

 

I had the same symptom, almost. My vacuum actuator was disconnected from the cable. When I pulled the cable out and held it with visegrips, it engaged the axel. The diaphragm seems to be a rinky dink method of transitioning axels. The previous post talks of manual cable system. Any further info on that system would be appreciated.

 

using the search function (found in the dark grey bar @ the top of the page) will give you all of the info you'll need on that much discussed topic.

in fact, a quick search turned up 20 threads that have cable posi-lock system mentioned in it, including a detailed how-to.