The vacuum to the actuator under the battery is constantly drawing. What controls the shut off on this so that the only time it runs is when I activate it with the 4x4 switch on the dash?

I was told there is a fuse under the hood. Does this control it? I can't find one under the hood. Where is it located?

Thanks in advance for the help.

 

You might want to provide some information about your truck... Year is required... If it is an electronically shifted transfer case, do you have the 3-button switch or 4-button (if 2nd gen)?

 

It's a 1996 chevy blazer.

It has the three way switch on the dash.

It has an electric control switch on the transfer case.

I have changed the switch on the transfer case and put in a new actuator but the vacuum won't quit drawing. I checked the tccm behind the kick plate and it clicks as does the transfer case.

Thanks again.

 

Did you verify the routing of the vacuum lines? If someone has rerouted the vacuum supply line directly to the actuator, putting in a new switch won't do a thing to change that. The other line at the vacuum switch on the transfer case is a vent line. When the transfer case is in 2wd, the actuator line is connected to the vent line. When in 4wd, the actuator line is connected to the vacuum source line from the engine.

If the vacuum to the actuator goes away when in 4wd, then you may have the 3-line vacuum connector onto the switch incorrectly or someone may have changed the order of the lines.

 

I'm actually having the same problem. I have a 99 blazer with the 4 button switch. I am able to shift into 2hi, but the front axle does not disengage.

I just replaced the vacuum valve (mounted on the firewall above the distributor) and this didn't help. The only way I am able to disengage the front axle, after being in 4hi or 4low and going back to 2hi, is to disconnect the vacuum line (that runs to the actuator under the battery) at the valve to relieve the pressure then reattach it.

The vacuum lines appear to be run correctly, however I don't have a diagram to confirm this. It runs from a T (providing vacuum from the manifold), to the vacuum valve, to the actuator under the battery.

Any thoughts???

 

Well, after MORE searching, I found the problem. Whoever worked on the solenoid (I called it vacuum valve above), or at least had the hoses disconnected, hooked them back up wrong. The one from the engine goes to the bottom and the one to the axle actuator goes on top. I never thought to try and reverse them.

No, it wasn't me when I replaced it earlier. I was VERY careful to hook it back up the same as I disconnected it.

I'm still keeping the new valve. I hear it is common for these to go bad and I do seem to be getting better vacuum to the actuator. Anyway, here is a link to a pic that solved my problem.

http://img.photobucket.com/albums/v9...2/0919-114.jpg

 

That was going to be my first question to you. The valve only seals one way as you have found out. Vacuum in reverse of the intended direction will cause continuous vacuum leakage through the valve. Glad you got it figured out!

 

What size socket will I need to remove the rotors from a 1996 S-10 Blazer LS 4WD.
Also. Recently noticed that when accelerating truck hesitates while emitting a High pitched whistling sound. Could that to be trnfr. switch line related as well . Almost as if the truck cant get out of it's own way... Any help Greatly appreciated....!

 

so my 4wd worked a couple weeks ago and now it dont work at all its a 95 with floor shifter the transfer case works but no front wheel power. it this vac or cable acutator in the front axle any input would help new to blazers was always a jeep guy.

 

I got a question for you guys, I have a 98 blazer 4wd with the 3 button switch on it and I can't shift into 4hi at all. My lights will blink on the switch then sometimes either go out all together or will keep the 4hi and 4lo lights on. is this just a problem with the vacuum line and I need to change it or what? any help would be great.