I have a 2002 chevy s-10 crew cab 4 wheel drive. The transmission will not shift from 2nd to 3rd. I have replaced the PCM, both shift solenoids, put in a transformer valve body kit that came with all solenoids and all valves. After doing so it shifted fine through all gears for about a 10 min drive. Then went right back to not shifting past second gear. When I pull fuse an take power from solenoids it gos into 3rd gear limp mode. So I don’t think it’s the 3/4 clutch. But I read on another forum that when u put it in limo mode that once you get over 25mph u should be able to accelerate pretty good. An if it dose then the 3/4 clutch is not bad. So gonna try that tomorrow. But if it’s not the 3/4 clutch then what else could be the issue? By the way I am not a mechanic. I’ve learned to do things on my own watching videos. So please try to keep that in mind when responding. I’ve read some other forums and I have no idea of some of the things they are talking about. So please try to break it down some where I can understand it. Any an all info will be greatly appreciated as I’m a poor farmer with two toddlers and a wife that has recently been disabled due to a car accident. So times are tight an I really can not afford to have transmission rebuild if it’s not absolutely needed. Thanks in advance

 

You have thrown a lot of parts at this thing by now it would have to cheaper to have just taken it to a reputable repair shop, but too late for that. Do you have access to a scanner, so that you can view what the pressure manifold switch and other sensors and solenoids are doing? If you want to just guess at parts, I would change the pressure manifold switch next.

 

Yea I have access to a scanner but have not been able to get my cousin to come over and hook it up yet. I said that “i” installed all those parts but I bought it from a friend that did. An he was guided by a transmission shop that obviously didn’t know what the heck was causing the issue so they had him just trying stuff. Then when all that didn’t work they wanted to rebuild it for him but he was ready to wash his hand of it so i bought it for very little. I have another one just like it I bought for scrap price. But not sure what condition the transmission is in bc I can’t get the thing to start. Pretty sure it needs a motor. But that is a whole nother project. What gets me is the fact that once he replaced all that it shifted fine for about a ten minute drive. Then went right back to not shifting past second. I read on another forum that I can pull fuse to shift solenoids an it will put it in third gear. Limp mode. Then said to drive it easy until I get it up to 25-30 an see if at that point it will accelerate as it should. Said if it dose then 3/4 clutch is good.

 

Ok, just talked to guy I got it from an he said he did put it in limp mode an drive it up to 50mph an 3rd gear worked. Said he had it on a scanner and it was commanding 3rd gear but not shifting. Said he checked map sensor and mag sensor an did not see a problem but that don’t mean one of them is not the problem. He just didn’t see a problem with them. Not sure how he went about checking those sensors but either way that’s what he just told me.

 

I was also told to try flushing trans oil cooler an cleaning new valve body. They said that maybe trans oil cooler had some trash in it an got caught in new valve body when running it the ten minutes that it shifted fine after replacing all those parts. But I can’t see how the trans oil cooler could have trash in it in the first place. But once again I’m not a mechanic so idk. Hoping somebody on here can help me.
I’m leaning more towards a wiring issue. Thinking maybe he wiggled some wires just right when working on it causing it to shift like it was supposed to for those ten minutes. But I really don’t know. In desperate need of some guidance from somebody who really knows these transmissions.

 

I would suggest starting over and unplug the big electrical connector on the passenger side of the transmission. This should cause the trans to default to 3rd gear. Drive the truck and see if there is any slipping, don't give it a lot of throttle until you get it rolling. If there is no slipping everything that is needed mechanically for 3rd gear is working. Once you have done this we can go from there.

 

10-4… I will do my best to try that tomorrow or as soon as possible and then update you with the results. I appreciate the info an guidance. More then words can describe. I’m a poor farmer with a lot going on right now an just can not seem to catch a break. My wife was in a really bad car accident an is now disabled. So not only did our income take a big hit but now I have two toddlers plus her that 100% depend on me for everything. On top of trying to run a farm which requires me to be available 7 days a week due to **** poor help. So believe me when I say that your help is GREATLY appreciated.

 

Ok so I put truck in limp mode an didn’t feel no slippage at all. Also, when it shifts into second it will continue to gain speed and rmp, just never shifts. The guy I got it from said he put a scanner on it and it is getting the command to shift but is not shifting. Said he checked map sensor and maf sensor an didn’t see a problem but that don’t mean one or the other isn’t the problem. I’m assuming he just physically looked at them an didn’t see anything wrong. I put a Bluetooth OBD2 scanner on it today an didn’t get any permanent codes at all. Got a pending 0301 which is cylinder one misfire but it is pending so the way I understand it is that it’s not misfiring yet but could be a issue in near future. Then I got a power train code of p0300 which is random/multiple cylinders misfiring. But look under hood an truck looks to have all brand new plug wires an distributor. I guess it’s a distributor. The thing that all the plug wires plugs into looks brand spanking new. An I would assume they changed plugs too when changed wires an all that so idk. Still confused about the transmission not shifting. Anybody got any ideas about what else it could be? Pretty sure it’s not 3/4 clutch being there is no slippage at all when in limp mode. Get it up to about 20-25 an give it gas an it accelerated fine with no slippage

 

When the trans is commanded to shift into 3rd gear both shift solenoids are turned off by the PCM turning off the ground to the solenoid. It could be that there is a short to ground it the circuit.

 

Yes that’s what I’m thinking. Figured that was most likely the cause being the fact that when the guy I got it from first replaced all those parts inside transmission an replaced PCM, he said that it shifted fine for about a 10 min drive. So figured he must of wiggled some wires just right causing it to work for those 10 mins. Also my thoughts was that if it was a bad sensor or something of that nature then it would not have worked for that ten min drive bc once they quit they quit.

 

So I’m trying to find the wiring harness that plugs into transmission an gos to the pcm. Can someone please help. Called the auto parts stores an they all keep trying to give me the internal harness. Any way somebody can send me a link to the one I need or the exact name of the harness I need. Or a picture of the one I need. It would be very much appreciated

 

This is not always the case. I have had shift solenoids work fine, then about 20 min into a drive they would stop working.

This is a gray connector from Rock Auto. part # ACDELCOPT1541
You will need to check the color of the connector on your truck. Have you checked the condition of the internal harness?

I would find which wires are the control wires for the two shift solenoids and check with an Ohm meter to ground. If you find that one is shorted to ground then I would unplug the PCM and recheck.
This website may have some wiring diagrams to help find your problem.
LT1 Swap

 

Keep in mind that disconnecting the wiring harness also causes the trans to run at max line pressure. So maybe, just maybe the 3/4 clutch is slipping with partial line pressure but can still hold with max line pressure.
With a good scanner connected, ignition on, engine off in a very quiet garage, you should be able to command the different gears and hear the solenoids clicking. If you hear nothing when commanding from 2nd to 3rd gear, you might have a stuck or shorted solenoid B. But if you can hear a click, then is likely solenoid B turning off and you don't have a short in the trans harness. Just pointing out other possibilities.

 

10-4… I really appreciate all the advice. I don’t have a scanner capable of doing all that but I’m hoping a family member’s scanner will do it. If not then I may take it up the road to a mechanic and see if he has one good enough to do this. An no I have not inspected the internal harness yet. But I’m sure the guy I bought it from did. He is pretty sharp.

 

I looked on rock auto website for acdelcopt1541. Could not find anything that looked like a grey connector. I tried putting part number in several different ways and just could never come up with a grey connector

 

Sorry, it is an ACDelco part, part # PT1008.
PACT also has one. I would post a link, but it is against forum rules.

 

So took it to shop an he is saying that everything electronically is working correctly and that there is something blocking the flow of fluid when it gos to shift into 3rd. He pulled valve body an checked it out an it looked good. So idk. He wants another 1400-1700$ to pull transmission and rebuild it. Idk what to do. I see online that I can get used ones for 500-1000$. I also have another one in a truck that won’t run but i don’t know if it works. Thinking I may just try putting other one I got in and hoping it works then if not then maybe try to find used one with low miles. But if I put a different one in dose it have to be programmed or anything like that or can I just hook it up an it be good to go?

 

So, after watching many many videos on how these transmissions work, I am really questioning my mechanic. I have questions I need answered asap. One being, is it possible for a shift solenoid to be working properly electronically but not having any fluid flowing through it when it is commanded to shift due to the screen on tip being clogged up? If so then that means his scanner could be telling him that everything is working electronically and that solenoid B is getting command to shift and he could even hear it click but it would not be allowing the shift to happen due to fluid not passing through as it should due to clogged tip. Am I correct? My thing is, he is saying that valve body looks good and is working properly. An that everything electronically is working properly. But still not shifting to third. So he says it has to have something blocking the flow of fluid an not allowing it to shift an that he would have to rebuild it to fix it. Now from my understanding, the blockage would almost have to be in the solenoid bc we know the valve body is getting fluid from pump bc it shifts from 1st to 2nd and everything else is working as it should. An he says that valve body looks good an is working properly. So that only leaves the solenoid. If I’m not mistaken, the fluid has to flow from pump, through the valve body, into the solenoid an out the solenoid in order to apply pressure to clutch’s an make the shift happen. So the blockage would almost have to be in the B solenoid. Correct? Or am I missing something. Y’all please don’t be mad at me. I’m just a poor farm boy trying to learn how this mess works an keep from getting screwed over. I appreciate y’all’s feed back an help a lot more then words can explain.

 

Yes, I think you are on the right track. But haven't you already replaced the solenoids? Did your mechanic remove the valve body and all of its valves to verify that none of the valves are sticking?

 

Yes I replaced them. But afterwards it shifted like it should for about a ten minute drive then went back to not shifting into 3rd. An yes he said he pulled valve body an everything looked good. Although he did say when he pulled the pan there was a little bit of metal in there. So I’m thinking that maybe the little screen on the tip of the B shift solenoid got clogged up. But he prolly hasn’t checked that bc his scanner said that the shift solenoids where working properly. Which they probably are electronically. But if tip is stopped up by a small piece of metal or something then the fluid would not flow through solenoid which would cause it not to shift. My question is, am I correct when I say that the blockage can’t be in the pump if the fluid is making it from pump to the A shift solenoid an allowing it to shift to 2nd? Or dose the fluid flow through two different paths from the pump to the valve body. My thoughts were that the fluid was getting through pump to valve body bc it shifts fine to second. So if none of the little passages are clogged that fluid flows through in valve body to get to B solenoid then that would me the blockage has to be at the tip of B solenoid right? Better yet, dose anybody know where dose the fluid travel when it passes through the B solenoid?