I have a 2000 4X4 with a little over 130,000 miles. A day or two ago the check engine light came on but I had no issues and it was driving fine. This morning heading to work it was still running good until I came off the freeway and had to stop at a light. As I started moving when the light changed I noticed that my engine RPM's were getting high and my Transmission wasn't shifting. Once I got to about 3200rpm it would shift into what I believe was 3rd gear. Fortunately I was close to the jobsite and didn't have to travel too far past that spot. I figured it was an anomaly. Once I was leaving work and got on the road it started doing it again. Once it shifted into what I believe was 3rd gear I was fine and it ran smoothly. Fortunately most of my drive home was freeway all the way and I only had a few stops on the way home in which it did the same thing.

There is no sounds or vibrations or anything out of the ordinary besides the check engine light and the weird shifting.

A little history because some items or past symptoms may be a sign of what the problem is for you Blazer gurus.

1) The transmission was replaced about 6 years ago.

2) This summer I made a few trips to a friends house to do some fishing, about 100 miles one way so it was a rare occasion for me to use the cruise control. When I got off of the freeway exit and was slowing down I could hear a loud sound coming from what I thought was the front end. It sounded as if a stick had got caught somewhere and was rubbing on a tire or something. A hard noise to explain but that is what it sounded like to me. I limped it over to my friends and it quit making the noise before I got there. On the way home it made the same noise as I was leaving his house. Not sure what to do I checked all under the truck but couldn't find anything wrong. I did eventually try hitting the 4X4 button and engaging it for a few seconds and then clicked it back to 2 wheel drive. Problem solved for the time being. The next trip it did the same thing and the same 4X4 trick worked again. Since then I have not used the cruise control and have never had the problem again.

3) About 2 months ago the radiator sprang a leak and had a crack in it so I replaced it with a new one.

I only list those items as I am not sure if any of it is connected. I have replaced several wheel bearings and done usual repair stuff that I am learning is common with Blazers but this one has me stumped. I am currently attempting to check the fluids but the vehicle was wrecked about 7 years ago and the hood is always difficult to get to pop because of that and right now is really being a bear to deal with. So while I take a break from fighting with the hood latch I found this forum and thought I would float my problem out there and see what thoughts you folks had. I plan on checking the transmission fluid once I get the hood popped and do some nosing around from there.

Any thoughts/help is appreciated. Thanks!

 

you got to scan it first, from what u say the trans is junk or if your lucky the 1-2 shift solenoid is pooped. if code is ratio error probalby junk, if a shift solenoid malfunction the change the solenoid. gota scan first

 

Well, I have to revisit this issue now. I work construction and have been on the road working up until the holidays and it is time to fix this problem. I did get the code and it is the 1-2 shift solenoid according to the code.

I am preparing to replace it and have read procedures here and elsewhere about it. I know the solenoid is up in the pan along with all the other solenoids. My question is before I attempt the repair, does anyone know the exact location in the pan? I know there are more than a couple solenoids up in there and according to parts listing the one I am replacing has a twin brother solenoid in there too. I am afraid I will get it torn apart and not know which is the one I need to replace.

Before I get the "You should change them all" answer. Money IS an issue and I am trying to get this done on a budget.

I drove it today, checked the fluid and added some. It still has the problem though. It occasionally will shift correctly but not often. Outside of not wanting to shift to 2nd gear the transmission runs very smoothly.

 

Diagram

I think after a bunch of web surfing I found what I needed on my own. Posting it to help anyone else who might need it. I found several other pics & diagrams if people need them let me know.

 

I finished the repair this morning and it is shifting smoothly and running great. The "diagram" I posted in my last post was very helpful in making sure I replaced the correct solenoid. There are two and they are identical, one shifts from 1-2 and the other from 2-3. It would probably behoove people to replace both while you are in there but I am laid off right now and need to pinch my pennies so i didn't. The solenoid for 1-2 was on the front of the pan on the drivers side, verify on diagram to make sure you understand.

Some things that may be helpful to those who are attempting this repair.

1) There are two different size pans on the transmission, one being shallower than the other which calls for two different thicknesses of a filter. No way to tell without measuring the pan or pulling out the filter and comparing it to the replacement to ensure you have the right one. If you use the wrong size filter it can result to more troubles once you put it together. I read some horror stories online that the transmission would not shift into ANY gear when the wrong filter was used. I purchased both sizes beforehand to make sure I was OK. They only cost $10-$15 each with gasket so no big deal and you can return the one you don't use.

2) There is no drain plug in the Trans pan(unless someone has put one in on their own) so you are going to spill fluid everywhere when you try to maneuver it out from between the cross member and exhaust. You could remove the cross member but it is a lot of work for not much reward. The pan WILL COME OUT without removing the cross piece, it just takes some maneuvering to slide it out. Be prepared for the spillage of fluid though.

3) You will need a ratchet and a 10mm and 13mm socket along with a universal joint(knuckle) and extensions. You can use 3/8" drive on most but 1/4" is a lifesaver on a couple. A screwdriver to pull the clip on the solenoid and a putty knife to clean off the old gasket. A huge drip pan is good also as there are about 4 to 5 quarts of trans fluid that is going to spill everywhere if you don't have a drain plug.

4) While you have the pan out you might as well help yourself out in the future and take this opportunity to install your own drain plug. I wish I had but it was an afterthought as I was putting everything back together. A drill and tap and a universal drain plug will only take a few minutes to install. There is a round spot on the pan where it looks like GM wanted to put a plug but decided against it as it would make our lives too easy apparently. Had I not been stranded with no ride to get what I needed while I repaired it I would have done so. Make for an easier, less messier job next time.

I believe that covers it. If anyone has any questions feel free to hit me up. I am no mechanic, just another regular guy who fixes his own cars when he can.