Hey guys I have a 2000 2dr 4x4.It wont go in 4wd.If I put it in 4hi&then in park&try to turn my drive shaft it wont turn so I know the t case is working.I'm guessing it has to do with the vacuum I'm wondering anyone has any troubleshooting tips?I'm not sure if I should start by replacing the vacuum actuator & vacuun switch.Also I dont know if this would have anything to do with it but if my heat or air is in the off position it will still lightly come out of the vents.Well thanks in advance!

 

I had the same prob in my 98 with 3 button switch. Turned out someone had the axle tube apart and put it back together wrong, after we fixed that i replaced my vacuum switch and still nothing....after many scratches of the head i figured out that the switch i bought was leaking. You could hear it with the vehicle running if you crawl under the transfer case. I had to order my switch from the dealer but it turned out to be cheaper there anyway. My heat/air sometimes blows a little even in the off position and my mechanic said it was the control head itself not shutting off the blower. I have computer controlled climate and the control heads are ridiculous hard to find and expensive.

 

Thanks for the reply I'm gonna check the switch.

 

Here is a simple test for the axle engagment;
Remove battery and pan, lift right front wheel off ground, connect Ohm-meter to axle switch.

Note switch should be "Open" or very high Ohms. Turn wheel and notice feel and observe front drive shaft. Wheel should turn free and drive shaft not turn.

Now pull 10 in of vac on front engage diaphragm with hand vac pump. Notice if vac holds or bleeds quickly.

Switch should now be closed or very low Ohms.
Turn wheel and notice feel and observe front drive shaft. Wheel should show more drag* and front drive shaft should now rotate with wheel.

Now, release vac below 2in. All conditions should revert to original.

*Note; If TC is in 4W position, then engaging the front axle will stop the front wheel completely.

 

your on the right track. i know just about everything with my 4x4 after taking my transfer case out and blowing out most of the lines.

one of the problems it could be is the actuator under the battery tray could be ripped. even the smallest hole can cause a failure. then check the lines. there should be a vacuum line going up over the left hand side valve cover or right next to it. it Ts off into a switch of some sort and then it goes to the switch. if you dont have vacuum there the switch isnt going to work. i put one of those new transfer case vacuum switches on my car and it didnt work so i just put the old one back on and it works right away again. must be some new redesign of some sort. either way. check your actuator first. then check the transfer case switch. if you can get it off a good check to see if it works is to put a straw in the end across from the shaft that the lines feed into. when you blow it should only come out the right side and once you push the switch in it should switch to the left hand side.

 

OK the actuaror seems fine,the cable seems fine,all of the lines seem fine....I pulled thw vacuum switch&the ball on the end was pushed in.The new one they sold me wasn't so I was hoping that would fix the issue...but nope!Stilno 4x4

 

do you know where the main vacuum line comes from the engine? if you look at the ball, follow the lines back. one goes into the dash for the HVAC, one goes into the engine and one goes down to the transfer case. if you pull the one connected to the engine there should be vacuum. i would start taking lines apart and seeing where you have some blockage.

 

Ok so this is gonna make me sound pretty stupie I'm sure but...one of the hose to the switch which I thought went to the actuator broke when I tugged on it so did the one on the actuator.Now I'm not sure if these are the same ones are not.Also on the passenger side right before&above the cat there's aY Shaped fitting for the vac lines&one of them only have a small part of hose left on so I'm not sure of It coulda been a part that broke off,or where it goes.I also noticed the other day there is a piece of hose coming off the top of tue tranny close to the tcase?????thought maybe a vent but there's no filter.

 

Something else to consider is the condition of the vacuum lines. I had the same problem but my lines were dry rotted. Pulling vacuum caused my lines to collapse and boom no 4x4. Just a thought good luck.

 

http://dl.dropbox.com/u/837001/Blaze...e%20Vacuum.JPG

This diagram shows all the vacu lines in the system. Notice there are "3 Vacuum Ts" under the hood and one "check valve". These are all on the driver's side close to the power brake booster. Three T's, a check valve and a resevour ball or tank. All pushed in a small area. If your Cruise does not use vacuum, then there will be only two T's there, but still a check valve. Inspect this area closely.

http://dl.dropbox.com/u/837001/Blaze...D%20Vacuum.JPG

This drawing gives a little better view of the Transfer Case, Vacuum Switch and how it's hooks to the front axle.

If you get tranny fluid into the vac lines, don't worry. Fix the source, but a little oil or tranny fluid will not stop any vac system from working. Eventually the fluid should work it's way into the intake and simply be burned by the motor. No biggie once the source is corrected.

The Vac switch on the transfer case is a simple plunger, spring, steel ball, two o-rings sliding in a plastic cylinder. Will work forever unless dirt gets in the system. If the ball hangs in, try flushing the valve with WD-40 and B-12 or other light solvant and oil. Mine came back to life in a few seconds once the crud was washed out.