i took my battery tray out and noticed my actuator is staying sucked in and not releasing to dis eng front diff. and the line has continious vacuum? help please bad actuator or somthing else?

 

If there is constant vacuum at the actuator under the battery, then you likely have a bad vacuum switch at the transfer case. Or someone has hooked the vacuum line to the actuator up to constant engine vacuum.

What are you working on? Year and transfer case modes (2 button, 3 button, or 4 button w/ auto4wd)?

 

98 s-10 blazer, 3 switch and yes its constant vacuum pressure.

 

Makes it easier.

I would start by following the vacuum line from the actuator. It should go to the transfer case switch. If it does not, there is your problem. If it does, then the switch must be bad.

 

I followed them down pulled em off of the switch and it is on it and fully lined up on the pin, would you say the switch is bad causing it to have constiant vacuum or is that a guess

 

That is the only thing between it and the engine manifold vacuum. So unless there is something internally wrong with your transfer case, the switch is bad. Even if it were to turn out to be something internal to the transfer case, you would still start with replacing the cheap vacuum switch.

 

i replaced the vacuum switch and it works great now the pressure ball was stuck all the way in it, thanks for your fast help!

 

I have the same problem mine just goes a little deeper. May be more than one problem actually. My vaccuum actuator stays engaged as well, Even after sitting overnight and leaking off some it will within about a mile of travel re-engage. I pulled the lines loose at the transfer case and bled the system off and I got a little tranny fluid out of the lines. I am also having problems with fluid bilching out the tranny vent. These two problems started and the same time. I changed the filter in the tranny thinking that the filter could be causing a little back pressure. I checked my cooler and the flow there is great! Also something of note....when the fluid bilches out of the vent tube on the tranny it is COLD! Even after about twenty miles of driving it comes out COLD! Go figure? Are any of the 4L60E tranny's vaccuum modulated? Or are there any vaccuum control pots in the tranny that could have a busted diaphram that is pulling tranny fluid into the system? Please help.....this is my only driver!

 

Oldbowtie,
Is fluid coming out of the transmission vent (just behind the bellhousing on the top of the transmission) or the transfer case vent (on top of the transfer case)?

Your problem sounds like a bad vacuum switch coupled with a bad input seal to the transfer case. You can verify by removing the fill plug (upper plug on the back of the transfer case). If fluid pours out, the input seal on the transfer case is bad, allowing transmission fluid in.

You will need to do a good job of flushing the vacuum lines of all of the transmission fluid. Hopefully it did not make its way into the HVAC system as that can be a royal pain to clean out.

The 4L60E is an electronically controlled transmission. There is no vacuum controls on it.

 

Thanks for the reply! I actually did mistake the tranny vent for the transfer case vent. Turns out the vacuum switch is the culprit....it is my understanding that this transfer case runs in dexron......is that right? I did a complete vacuum system clean out with my vacuum pump. Took all the lines loose from their various locations and blew them out with air and I think I caught it before it got too far out of hand. My 4wd functions very well now and things are coming together! Thanks for the help guys!