93 s10 blazer/4x4 troubles

[BlazinUP]

hello........
i have a 93 4.3 cpi s10.
the 4wd works well for a while ...then after some time
when i try it again..nothin but the initial lights when i start it up....
i push the buttons and nothing....
to get it to work i disconect the battery for a few mins...works fine...
then it happons all over again.......
can anyone help...im stummped

thanks in advance

[BlazinUP]

i see alot of peps looked at this...but no responce:/
am i explaining this problem badly?
or does no one know what is is or could be.
i could use some kind of input...someone has to have some kind of idea......:/

[BlazerLT]

Vacuum transfer case actuator.

Check for bad vacuum line.

[BlazinUP]

first off...thanks LT....
i see you have helped alot of peps here.

i was wondering....if theres a bad vacuum line...
wouldnt it not work at all or eventually go out of 4x4?
cause when its in 4x4 it works great 4h/4l/ shifiting etc.
its just that the working only lasts about a week ..then i have to do the battery trick again.
and so on and so on :/

or do you mean that theres a thing called a:
vac trans acuator that may need to be replaced?
if thats the case ill tell my mechanic to replace....
cause he couldnt find the answer.
again ...thanks for your help

[BlazerLT]

No problem with the help, I love to aid people in their diagnosis.

Yes, I am talking about the vac tranferfer case actuator.

Prone to failure in that year.

[BlazinUP]

thanks for your help LT.
ill get that checked out.

[alleng]

When the 4wd computer encounters a "problem" it goes into a default mode.(2wd). When you disconnect the battery it does a relearn and works until it encounters the problem again and shuts itself down again. First, check the ground wires on the back of both cyl heads to be sure they are tight. If that is not the problem, you probably have a bad encoder motor.(shift motor assy ) They are not cheap so if you know someone who will let you try one, new or used, for a few days that may be your best bet. They are not hard to change.

[BlazerLT]

Originally Posted by BlazinUP

thanks for your help LT.
ill get that checked out.

no problem, more often than not on a electronic 4x4 system, that will be the problem.

And with the Blazers it is almost definite.

[BLZNFUN]

I had the same problem. My 93 would go into low range most of the time but not into high range 4x4. When it would attempt to go into 4 high, both low and high range lights would flash and then it would stop... My mechanic had to replace the electronic shift module on the transfer case, the vacuum acctuator on the front differential, the safety neutral switch, and adjust the shift lever. After all that it works fine. Cost me about $489...

[vtmecheng]

Hey BlazinUP, don't just start to replace things. Here is a checklist for you to follow:
1. When the 4X4 does work, listen for the motor attached to the transfer case to work. If you need to, get under the truck and have someone else push the button so you can really hear it. Then, when the 4X4 doesn't work check the motor again. If you don't hear anything then you know your front diff. vacuum actuator is fine and you have another problem.
2. If the motor continued to shift in the transfer case then find out where the vacuum actuator is on your truck, probably under the battery. Put the truck in 4X4 and feel if it moves, if not then pull the hose off and check for vacuum. If there is vacuum then your actuator is bad and replace it. If there isn't then either your hose is bad or the switch on the transfer case is bad.
3. If the motor didn't shift the transfer case then check all the connections and ground wires like "alleng" said. If they are good then its a good bet your motor is bad.
I hope this helps and feel free to ask any questions along the way.