1994 S-10 Blazer 4.3L Transmission shifting problem

[crazed2881]

My transmission won't shift any higher than 2nd gear. It down shifts ok. Overdrive works. 95% of the time drive doesn't work. 1st and 2nd obviously work. When it comes time to shift from 2nd to 3rd, it slips. If I back off the throttle slightly it seems like maybe it catches 3rd sometimes but mostly not. Seems like it's still in 2nd gear. Does anyone have any suggestions on maybe what needs to be replaced. Only thing I can think of is a shift solenoid or maybe, well I don't know, that's why I'm here to see if anyone can HELP! PLEASE... Let me know what you guys think. Thanks

[MT-2500]

How is the fluid and fluid level and filter?
What is the mileage and service history?
Any codes or check engine/transmission lights?
Is the engine running good and spedo working good?

You need to get it on a transmission/engine capable scanner and read out data and check for codes.
Post back codes and other info.

[crazed2881]

I have a 1994 chevy s10 blazer 4.3 L. Vortec Engine w/ 4L60-E electronically controlled automatic transmission. 160k miles.
The engine runs great. The spedo works fine. The tranny fluid is new. I just changed the fluid and filter. The old fluid was not burnt. This problem occured after I put the truck back on the road after parking it inside my garage for 1 year. When I parked the truck everything ran fine. It seems to be in what is called Limp Mode. The check engine light is not on. I can hook up an engine scanner to see if any codes come up but I'm not so sure. I don't know what a transmission capable scanner is??? It is totally different scanner that hooks up to my transmission or is it a special type of engine scanner that reads transmission codes?????? I believe the solution to my problem is behind whatever this scanner will tell me. First I need to know what kind of scanner this is.

[MT-2500]

Originally Posted by calvin22

I have a 1994 chevy s10 blazer 4.3 L. Vortec Engine w/ 4L60-E electronically controlled automatic transmission. 160k miles.
The engine runs great. The spedo works fine. The tranny fluid is new. I just changed the fluid and filter. The old fluid was not burnt. This problem occured after I put the truck back on the road after parking it inside my garage for 1 year. When I parked the truck everything ran fine. It seems to be in what is called Limp Mode. The check engine light is not on. I can hook up an engine scanner to see if any codes come up but I'm not so sure. I don't know what a transmission capable scanner is??? It is totally different scanner that hooks up to my transmission or is it a special type of engine scanner that reads transmission codes?????? I believe the solution to my problem is behind whatever this scanner will tell me. First I need to know what kind of scanner this is.

You need a 1994 year engine/transmission capable scanner.
A high end high dollar scanner that will read out transmissiuon data on that year.

Best to find a good repair shop that has one and pay them to check it out for you.

Post back what codes and data they get.

[MT-2500]

A lot of 1994-95 gm were a change over years from obd-1 to obd-11.
They require special eng/trans spefic scanners and adapter ables to read out the engine or transmission data and codes.

If you have pin A and B on diagonestic connector you could try jumping them and see if you get any codes.

Snap on and the GM tech scanners are two scanners that will read out data and codes on them.
But run up to 5 grand in dollars.

[crazed2881]

I had my transmission read with a snap-on transmission capable scanner and found out that my problem is an internal mechanical problem. Not an electrical problem. The scan basically told the mechanic nothing which led him to this conclusion. Does anyone know where inside my transmission my mechanical problem may be????????????? Can anyone tell me if my transmission is w/CTF or w/o CTF????????????Thanks for your help. I plan to rebuild this transmission myself. Any suggestions on exactly what all I should replace??? Just don't want to do the job just to find out I left something out after I've reinstalled...

[Blue Bowtie]

Take a close look at the 3-4 clutch pack (a known weak point) and the actuation system (a.k.a., piston and mainshaft seals) for the 3-4 clutch pack.

The V-6 variety of 4L60 has fewer friction plates than other versions, so they tend to go more miles before the piston can overtravel and stick. Still, with that kind of mileage, wear is to be expected.

[MT-2500]

Originally Posted by calvin22

I had my transmission read with a snap-on transmission capable scanner and found out that my problem is an internal mechanical problem. Not an electrical problem. The scan basically told the mechanic nothing which led him to this conclusion. Does anyone know where inside my transmission my mechanical problem may be????????????? Can anyone tell me if my transmission is w/CTF or w/o CTF????????????Thanks for your help. I plan to rebuild this transmission myself. Any suggestions on exactly what all I should replace??? Just don't want to do the job just to find out I left something out after I've reinstalled...

A good scanner should show what gear the slippage in if it has slippage.

If the problem is internal and a lot of miles on transmission.
Days of just throwing a kit in one or a one spot repair is over.
Best to take it down to bare metal and clean it up good enough to eat off of.
Inspect all parts with a good eye ball.
Replace all seals and clutches and sealing rings and thrust washers and check all plastic hard parts for wear.
Some sealing rings and clutch packs will require special tools to install.
A transmission hand book will show you what you need and what updates may need done.
If not already replaced done replace the sun shell gear and shell with the updated heavy duty one.
If rebuilding always replace the converter with a good quality rebuilt.
Be sure to flush oil cooler/coolers and lines.
Get a good transmission hand book to help on repair.
Also.


http://72.19.213.157/files/4L60ERepairs.html
http://72.19.213.157/files/4L60ERemoval.html

Good Luck

[lynndiwagon]

Calvin, good luck with the re-build. It is certainly possible for a shade tree mechanic to overhaul one of these.....I did. But, you need a lot of time for this. Now that I've done it, I could do it easily, no more mystery. You need a good workbench that you can drill holes in, and some special tools. The only one I couldn't fabricate myself was the teflon seal installer and re-sizer. you will need two different sizes for this. They can be purchased but pretty expensive. I did buy one for the smaller input shaft teflons.....$25.00. I did not replace the two larger ones for lack of a resizer. Other tools are easy if you have some mechanical sense. I purchased the ASG book and the DVD. You will need both. They're about $25.00 apiece and worth every penny. I used brake cleaner for the clean up and cooler line flush. Also, better have a good compressor for cleaning and checking pistons and clutch packs. I air tested every clutch pack before completing job. All of my stuff will soon be on ebay. Good luck to you...and listen to MT2500.

Lynn Wagoner

[crazed2881]

Thank you guys for all of your help and advice. But don't quit on me now. I'm sure there is much more I need to hear. I am ready for the challenge and ready to face the mystery of the Automatic Electronically Controlled Transmission. This will be my very first transmission rebuild. So keep that much appreciated advice coming. I will be posting much more as I dig in and get my hands dirty. Thanks Again !! Oh hey does anyone have a recommended rebuild kit that I should buy? There are so many out there. I want to make sure I get the one that has it all.

[Blue Bowtie]

I've had good luck with Makco (www.bulkparts.com), but there are many reputable sellers of transmission parts out there. Most local parts houses are not likely to stock trans parts or kits, so they would be ordering them just like you. The other thing to bear in mind is that you will not know what hard parts you might need until you disassemble the trans, so it may take a little longer than you anticipate while you acquire parts.

MT linked in my rebuild overview article, and that should give you a basic idea of what you are undertaking. Make sure you get a repair manual specific to your transmission before starting, as you will need the specifications and details they provide.

[lynndiwagon]

Be sure and get that DVD. It gives you step by step teardown and rebuild. I would call it "invaluable", plus it's fun to watch if you like mechanical things. These transmissions are ingenious. You might get it first and watch it through before attempting rebuild.

[crazed2881]

Hey guys, thanks again for all of the helpful feedback. I have undergone the removal of my transmission. I would however like to aquire a used transmission from a salvage yard to keep my truck going while i do this rebuild. One question I have that keeps coming up is: is my transmission w/opt ctf or without opt. ctf. WHAT does this mean and how do I find out or know if my transmission has this or not. I want to make sure I'm getting something that will work in my truck. I have a 4x4 with a W vin if that helps? Can anyone tell me ???

[lynndiwagon]

I don't know what that option is but one piece of advice is to replace that seal on the front of the transfer case while you have it out....Chevy for about 12.00.

[jynx715]

Originally Posted by calvin22

Hey guys, thanks again for all of the helpful feedback. I have undergone the removal of my transmission. I would however like to aquire a used transmission from a salvage yard to keep my truck going while i do this rebuild. One question I have that keeps coming up is: is my transmission w/opt ctf or without opt. ctf. WHAT does this mean and how do I find out or know if my transmission has this or not. I want to make sure I'm getting something that will work in my truck. I have a 4x4 with a W vin if that helps? Can anyone tell me ???

I have the same problem as you had discribed your trans shifts 1&2 then slips what did you do to resolve the problem. you said you were going to rebuild the trans. could you tell me what you found the problem to exactly to be. thank you any help from anyone would be helpful