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"Hard Shifts" in Impala Recent Transmissions

I have an '06 Impala SS with automatic… transaxial failed at 47,000 miles and was

replaced. Mr GoodWrench says that “hard shifting” is a common problem in Chev. The replacement has been “hard shifting” from the start and expect another fail… 25,000 miles, so far. Anything to adjust “hard shifts” possible?

I have a 2006 Impala SS also, with about 46,000 mi. I have been having an issue with either the transmission, or maybe the torque converter, not sure which. My only issue is that sometimes while I am stopped at a light,when turns green to go, there is a 1 second hesitation, then kicks in and goes, with a little thud. Don’t know what is causing this, is it the hard shift issue or not.

The car may go a couple weeks without happening again, then could happen a couple ties a week.

It only happens in first gear, when starting from a complete stop. Shifts at any other time are smooth, no matter whether it’s a gradual acceleration or a hard one.

I used to think my problem was caused when, about a year and a half ago, traveling from NJ to NY, while cruising about 80 thru PA, coming up on a roadside trooper and not wanting to light up my brake lights, I let up on the gas and also attempted to downshift (have auto. transmission) to 2nd gear, so I’d be doing 65-70 going by the trooper. I moved the lever the wrong way and got reverse instead of 2nd.

With an older car, I’d be picking up my tranny off the thruway, but the Impala just stalled, cut off the engine, rolled to a stop. Afterwards, I cleaned out my pants, I was able to restart the car and continue on.

Unfortunately, I repeated this goof a few months later. At least this time I knew what to expect, knew what to do, and pants were’nt affected.

But after these 2 incidents, I noticed this occasional issue with the transmission or torque converter. Question is, did I cause it, or is it a transmission issue with Impalas?

Thanks Jim,
This is exactly how my Impala behaved before (and after) the transaxal failure. It is a very intermittent behavior just as you describe. I do not think that anything you did or will do, will change the out-come… mine began its long decline at 47,000 miles. GM has issued service bulletins on this issue, your dealer can access them. No real adjustment possible, just replace after fail happens in another few 1000 of miles.
Good to know you can stop by going out of gear, a Toyota runaway could not stop out here last year… caused all the “gas pedal” recalls you are reading about. Only issue I have now with GM is that the replacement transaxal is again having the “hard shifts” after 25,000 miles, which I believe will lead to another fail, sooner or later … all gears out, except reverse. Something for you to look forward to…sorry. Thanks, ImpalaDriver

Has the dealer checked this transmission yet?? GM had several software updates for this. You might want to have them check to see if your PCM has been flashed for this. The hesitation before the trans engages at stop lights could be a faulty PCS (Pressure Control Solenoid) which is not uncommon.


Hi Transman
Yes the dealer checked codes and diagnostics several times on the first transaxal over the course of the 4 months from when it first started “hard shifting” to when all forward gears failed. And the dealer has also checked codes and diagnostics several times over the course of the replacement transaxal’s “hard shifting”… never any codes or anything the dealer could find as a possible issue. Also have been in touch with factory techs from GM.
What they do note is that this type of system has been shown to be prone to “overheating issues” in their experience. Whatever that may mean… the tech who took apart the first failed tranaxal did find extensive discoloration and heat effects, in his words. Near the end of its life, the first tranaxal did some very odd things, lots of noises, heavy slipping, etc… I do not drive in any aggressive manner, very safe and sane older driver.
Software/firmware mods have been kept current over the 4 years since purchase…
Thanks for your inputs, ImpalaDriver

No activity since 2010 - maybe you found the solution? I am reading through existing posts before posting a new item, and this one seems to be similar to mine. Couple of exceptions: (1) The problem has been present since I bought the car used, in 2005, and (2) with about 36k miles so earlier than your starting point. Mine is 2004 model. I have been to 3 dealerships and 3 transmission shops over the years and no one can find anything wrong. Here I am 12 years later and after adding 130k miles, with no solution still. My details, in which you will see similarities:

  • At random, when traffic light turns green start pressing gas and hear the engine race with no movement, then it SLAMS into gear - I mean neck-snapping slam - and with a loud slamming sound
  • Even if I take my foot off the gas the instant I detect the revving and before it slams into gear, the slam still happens
  • Never happens when shifting from park to drive
  • Never happens when going in reverse
  • Has apparently never done damage to the transmission - still have the original, never rebuilt
  • There is no predictability - hot whether or cold, hot engine or cold
  • Bought the car in Denver and have lived in Colorado, Utah, Arizona since, as well as spending some time Wyoming and California (LA area) so issue seems altitude-independent
  • Can happen several lights in a row or once and then not again for months
  • The only thing close to a cause/effect relationship is that it seems to be more likely to occur when I use cruise control more often - which I do even in city driving when in a place where lights are well timed and keeping a constant speed reduces stops

So while this is obviously not costing me anything but aggravation and occasional discomfort to my passengers, I would like to know if this in detail is what you saw and if you found a solution… Thanks for anything you can offer.

How about going from neutral to drive?

Cannot say I can remember specifically shifting neutral to drive - have little reason to, with automatic transmission, and never thought to try doing it often enough to call it a “test”. But never happens shifting reverse to drive, as well as what I reported before.

Well, then test it. You probably have a sticky transmission valve body.

Throwing it into neutral at every stop might be a “work-around.”

Will give it a go. But since I can sometimes go a couple of months without a hard shift, will be difficult to really know anything for a good long time. And of course I have to remember to run this test faithfully. So it may be a while before you see any news on this. Thanks for your help.

Shifting to neutral does not seem to make a difference - still get some slams.

How many times has the transmission been serviced (fluid changed) in your 130K miles?

I’m currently working on a truck with about 115K and the automatic transmission fluid and filter have never been serviced

Obviously, I performed a fluid and filter service

I’m not sure how the truck made it this far, and I’m also not sure how much longer the transmission will last. I did my part. This was the first time I’ve ever worked on this particular truck, otherwise I would have serviced it earlier.

It’s just amazing it’s slipped through the cracks all these years . . . I believe it’s a 2001 model year