Impala won't shift after it gets warm

Here are three places to check. First, take a look at your Chevy’s transmission fluid level. It is quite possible that it is down slightly, not so much so that your transmission will fail, but just enough to cause seriously major slippage. We have covered how to check and change your transmission fluid at https://www.transmissionrepaircostguide.com/change-transmission-fluid/. Take a look at it for a thorough look at how to go about this step.

Second, it sounds as if it could be a problem with the torque converter control solenoid. Getting to this particular device requires a partial teardown of the transmission. By the time you get to it, you will likely find it more cost-effective to drop in a rebuilt transmission. It is not that this is an expensive part to replace, it is just that the cost of getting there — the teardown — is high. You are looking at a cost of about $1,800 for the teardown plus the cost of the kit and, possibly, the cost of a new torque converter and related hardware. If you have to add the these parts to the initial cost, you are looking at a total cost of about $2,500. It might make more sense to just drop in a rebuilt transmission and pay the extra $500 or so.

Thirdly, it might be a problem with the transmission control solenoid. Again, this is one of those parts that doesn’t cost that much. Getting to it, though, can be costly.

Here’s the thing about transmissions and error codes. It’s a hit-and-miss thing. If the error is strictly in the transmission and doesn’t impact the engine even indirectly then it is quite likely that no code was ever generated. And, the car’s computer control module (CCM) listens to only one or two of the transmission’s sensors so even if there is a problem, the CCM won’t log it. It thinks things are just fine, when they are not.

In my suggestions earlier, I mentioned two solenoids, the TCC and TCS. Over time, solenoids, since they are electronic, can become heat-sensitive. As the become more and more sensitive they tend to fail. Allowing them to cool down causes them to reset and work again. The result is that your transmission works as it should.

Note, that neither of these solenoids will likely generate an error code that is capturable by the CCM because they impact only the transmission and nowhere else. Since there is no error code generated, there is no error code to look up with and OBD-II scanning tool. That’s why the shop said there was no code.

You can have them fix the two solenoids but if you do remember it’s like the story of the 89-cent car part that only took $4,000 labor to install. The solenoids themselves aren’t that expensive. It is getting to them that requires lots of effort and time. The effort and time means you will be spending a lot on labor just to replace two solenoids. In reality, the shop is quite justified in suggesting that you should just replace your transmission for the reasons I just listed. You’ll likely spend the better part of $2,500 to replace either or both of the solenoids. Since that’s the case, it is better to just invest another $500 and drop in a rebuilt tranny.

The reason I suggest the rebuilt is the best way to go is this, as your mechanic goes through the various stages of the teardown and rebuilt, it is possible that various pieces can become distorted or damaged due to their manipulation. If parts are damaged, the transmission likely won’t work correctly when things are all closed up again. Given this possibility, it makes more sense to just swap out the transmission due to the location of the parts and their potential impact on performance.