1994 Chevy S10 will not shift into overdrive

1994 Chevy S10 will not shift into overdrive at all. It did this a couple times in the past but would eventually shift. The truck sat for a couple months while working on the brakes and suspension and now will not go into overdrive at all now. Took the rpms up over 4000 and speed over 40 and still no go.

First make sure the transmission fluid is at the correct level. If it is low, add fluid. Make sure you add the right fluid! Check your owners manual. While you are checking the fluid level, smell and visually inspect the fluid. If it has a burnt odor, you have a problem with the transmission fluid that may already have caused damage to the transmission. If this is the case, or if it is discolored, have the fluid replaced immediately and the screen replaced. The best method to replace the fluid is via the cooling system, especially if it has a burnt smell. If the pan is dropped and the fluid drained, the fluid in the torque converter remains. By the way, if there is in addition to a burnt smell you find small metal flakes or chunks in the fluid, don’t bother replacing the fluid, because you need a new transmission.
Even if the fluid is clean looking and has a neutral odor, try changing the fluid and replacing the screen.
Finally, at 40 mph the rpm’s should not be anywhere near 4000. It sounds as if you are not shifting into say, third gear.

As kizwiki noted you might be stuck in 2nd gear. That is the ‘limp home’ gear of a GM automatic transmission. Is the transmission making a 1-2 shift or just starting out in 2nd and staying there? Is the Check Engine Light ‘on’ or the overdrive light constantly ‘on’ or flashing? If so you might run this by an qualified transmission technician to have the PCM scanned for transmission codes and pull freeze frame data. Maybe the solution will be obvious once the codes are known.

Keep us in the loop regarding the solution to this problem.

These are additional comments:

The check engine/OD light is not on and has not come on in any manner. The fuild level is fine and was recently changed. Reading some other forums, it seems like this is not an uncommon issue. They suggested being in drive and manually shifting in to OD over 30. That is currently working. But none of thosesuggested a cause, other then replacing a couple of sensors. Likely going to have to try that.

Thanks for the ideas. I am hoping that the senor are not buried and can be replaced easily. I really not interested in tearing the front end apart of hitting the junkyard for a tranny.

First of all before you do anything. Will the transmission, when placed in “D” start out in 1st then shift up through any gears?? If it doesnt then you are most likely in limp mode which means the computer fixes the transmission in 3rd gear. In this case, I would first check power to the transmission. At the connector on the passenger side of the transmission, check the pink wire. You should have 12vdc with the ignition in the “ON” position. If the transmission is starting out in first and is upshifting at least once I would connect a scanner to it and see whether the computer is commanding the shifting. Let me know what you find out.


Hi Guys,
I also have a 99 S-10 4cyl with 164K on the clock. In the past several months the vehicle will shift out of 1st, 2nd, and into 3rd. It will lag and hang on until I push it over 70mph. Then it might shift into 4th.
Later driving at 65~70 it will down shift and up shift…
I had (last year the fluild changed. (frankly I wonder if they screwed it up somehow because it was fine prior to the trans place flushing and refilling…)
Now I’m worried that someone is diagnosing it: replace it!
Please adivse. I also placed some (expensive) trans fluid additive in and it started a minor leak! ( I think it is now stopped).
Please advise.

i have a 93 s 10 i changed the transmission fluid an filter now it wont go into overdrive any ideas ???