Hi, This is my first post so hello to all and please be kind. I have a 96 s-10 blazer auto 4x4 4.3 I need to replace this part but I do not know what it is called. Tough to tell auto zone that thingy on the side of the trans. It is on the driver side just above the vss and has three vac lines going to it. I think it may be a vac modulator or switch? Any help on what it is would be great. I have looked every where and went through chilton's but no mention of it.

 

If I understand your description correctly, it would be the vacuum switch. It controls the front axle vacuum actuator when the transfer case goes into 4HI or 4LO.

 

Thanks, My description was a little off but that is what it is. Did not fix my problem but the 4x4 works now.

 

Well, what is your problem?

 

Trans shifts 1 to 2 and I think 2-3 then starts winding out like it is in neutral if you let of the gas for a second it will shift. Reverse works perfect. I have changed the filter and fluid that did no good. So I pumped about 4 gal out through the dip stick tube and replaced it. Now the fluid looks red like it should but. The fluid I pulled out was very black but no burn smell and there was nothing in the pan as far as solid metal or what not. I am kinda at a loss as what to do next. From what I have read there a ton of things that can cause the trouble. It does seem to idle a little eratic when it is put in gear. It jumps up for a couple of seconds then calms back down.
Thats what I thought the other thing might fix. Just one more tid bit is that the pcv valve rattles back and forth so loud that you can hear it inside the cab going down the road or any time it is put in gear. I put a new one in and that little ball inside it is just going nuts any time you put it in gear. That sound goes away in park or neutral. Sorry to get long winded but figure I will tell you everything at once.

 

See if the throttle cable is resting on the PCV vacuum hose to the intake manifold. If it is, reposition it so it is not. That has been a known way for the noise to be transmitted into the passenger compartment.

As far as your transmission problem, it sounds as though you have lost 3rd gear or that 3rd gear is slipping. If you push the truck hard (WOT from a stop, do you notice any slipping in any other gears or is it only after it shifts into 3rd? Dark fluid is not a good thing as it means that it got quite hot even if it does not smell burnt. You may have a valve hung up that is not allowing the transmission to complete the 2-3 shift or is not applying the proper line pressure to the clutches after the 2-3 shift.

 

It only seems to be after it shifts into third. hit the throttle hard and back off for a second at will go ahead and shift. It has to be at a very high rpm for that to work most of the time. But some times a small rev and let go will make it grab the next gear and then all is well.
I am honestly just wanting to make sure that I am not missing something simple that might save me from A rebuild or at least get me by till I can afford it. I am afraid that a tran shop will just say rebuild from the word go. If they say that then I am looking at a couple of months before I could do it.

 

See the image below for a No 2-3 Shift or 2-3 Shift Slips, Rough, or Hunting:

It shows the possible causes for the above mentioned symptoms.

 

Thanks for the quick reply. Wow that seems foreign to me. I am fairly good with a wrench. But is there like a good "hillbilly" way to narrow that down or am I just going to have start at the top and work my way down the list?

 

If you really want to dig into it, I suggest you get yourself the ATSG manual for the 4L60E. It will tell you where the components are. Much of it deals with the components in the valve body.