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Chevy Silverado and GMC Sierra Transmission Problems



  • bigman55434bigman55434 Posts: 22
    Nothing wrong with the 6L80/90 transmissions? Really? That's a BOLD statement to make when you have nothing to refute what everyone is observing. If there was nothing wrong with my 2008 Sierra's transmission, why did GM give me $3k in buyback money (aka Purchase Assistance) towards my next truck? Why is it that my 2011 Sierra completely failed to upshift from 1st to 2nd, on a level road, 70 degree day, and light throttle input? It revved past 4000 RPM's before it SLAMMED into 3rd or 4th gear. It did that twice in a row before it started sorting itself out. As for learning mode, my transmissions have all shifted better when they were new. They seem to get worse as time goes on. It does not take 20k miles for learning mode to work. Its a few hundred at most. The problem with these transmissions, for the most part, is the horrible TCU and ECU programming. In an attempt to manage torque and get these tranny's to last 100k miles (for the warranty), they have ruined driveability.
  • The problem you had with your 2008 Sierra is irrelevant to the discussion of the current transmissions. The transmission in your 2008 was a 4L60e and has absolutely nothing in common with the 6L80e that was first installed in the Sierra/Silverado in 2009.

    A little "googling" turns up few complaints with the reliability and durability of the 6L80e/90e transmissions, in fact, most, who are knowledgeable about transmissions, think they are excellent.

    As long as the transmission and computer in your 2011 Sierra are stock and unmodified, I am sure that GM will take care of you.
  • chuck1chuck1 Posts: 1,405
    The Amsoil transmission fluid is actually better than the GM new Dexron 6 because it is A FULL SYNTHETIC. GM has never claimed the new Dexron 6 is a full synthetic. In addition, the Range Technology product is a box that plugs in to the OBD port and sends a MESSAGE THROUGH THE ECM but DOESN'T OVER WRITE IT.

    The range technology product turns off the AFM and all reports states it takes the clunkiness out of the powertrain.

    Let's face it-the torque mgmt, the AFM, and the poorly designed 6 speed transmission takes a lot of pleasure OUT of owning this vehicle.

    I know, I own one.
  • I'm sure Amsoil transmission fluid is a fine product, but until it is Dexron VI certified, I won't use it.

    Thanks for enlightening me about the Range Technology product. I thought it was a tuner, but I see now that it just fools the computer and locks out AFM via the OBD port. I can do the same thing by putting the transmission in M5.

    I must not be as demanding as you are... I like driving my Silverado.
  • hblackhblack Posts: 1
    I have a 95 1500 silverado. When I first drive it the transmisson shifts just fine. After about 10 miles if I ever stop and go again it will not shift out of 2nd gear. From that point forward it remains in 2nd gear even when taking off. Once it cools down it will shift through all the gears again. I've replaced the computer box behind the glove box and also changed the ignition switch. I was advised that sometimes a worn ignition switch will not power up the part of the computer that tells the trans to change. Any ideas??
  • chuck1chuck1 Posts: 1,405
    You can do the same thing by putting it in "M5". But with the Range product you get the sixth gear back.

    I am sure you are aware that "certification" means paying a fee to GM to become certified and then a Royalty for each quart sold. In addition to the standard tests.

    I am not an engineer, but I would venture to say the Amsoil meets or exceeds GMs requirement as the product is already formulated. If you browse other forums online-many Silverado owners are reporting good results and improved powertrain smoothness with the two products I mentioned above.
  • My point is that every 6 speed truck transmission GM has made since 2006 has exhibited the same poor driveability, clunky shifts, and missed shifts. They need to fix it.
  • chuck1chuck1 Posts: 1,405
    They are using the same transmission in the 2014s. I am hearing the shift to 4cylinder mode is smoother as is the transmission.
  • tooheeldrivetooheeldrive Posts: 17
    edited June 2013
    That is just an absurd statement. You need to get (your transmission) checked out.
  • 2001 Silverado: Transmission all of a sudden will not shift from 2nd to 3rd gear. Oil is new last summer, level is ok?

    I blew a line at night last summer and smoked the 3rd gear clutches. Transmission was rebuilt and new filter and oil switched out. Electrical?

    I also hit a deer a few months ago and had to replace front differential. Don't know if this had anything to do with it.
  • chuck1chuck1 Posts: 1,405
    Do you own a truck with the six speed transmission ? These transmissions are not smooth shifting. Let's just say they are less than refined.
  • donl1donl1 Posts: 109
    I must have got a bad one...mine has always shifted fine. ;)
  • ceb66ceb66 Posts: 70
    edited July 2013
    Since this is a site dedicated to car purchases, I'm certain Edmunds would want their readers to know what other new owners are saying:

    If you're considering a new 2013 GMC Sierra or 2013 Chevrolet Silverado make sure you take it on a long test drive at 45 mph on level ground. Turn the Driver Display to Instant Economy. Ask the salesman if the Active Fuel Management AFM is seamless from four cylinders to eight. Sure GM says its seamless from eight to four. You're essentially coasting. During the test drive, determine if the transmission is growling as the AFM activates all eight cylinders. Make sure you grill the salesman with questions such as "has General Motors received overwhelming complaints about this transmission"? "Have they received complaints about clunking"? "Are there General Motors maintenance directives referencing all of the complaints"? "Do the directives instruct the dealer to avoid the issue and tell the owner "it's operating as designed"?


    In their latest seasonal publication, GMC The Magazine, on page 5, they state the "engines seamlessly switch to four cylinders." Hey GMC Magazine, why not describe the opposite, the switch back up to eight cylinders? Oh, that's right, I'm sure omission of that little tidbit was an oversight! The switch up to eight IS FAR FROM SEAMLESS. It's actually incredibly annoying and no, you never get used to it. A friend put dual pipes and glass packs on his. That makes the growling and lagging even more noticeable.

    New General Motors GMC Chevrolet Truck buyer beware and drive these trucks extensively before purchase of these new GMC Chevrolet trucks.
  • obyoneobyone Posts: 8,065
    edited July 2013
    So to summarize what you're saying is that the GM trucks are a pile of junk?

    Just trying to clarify.
  • chuck1chuck1 Posts: 1,405
    edited July 2013
    Actually, those who have driven the 2014s have said that the AFM switch is now "seamless".

    The problems you describe are isolated to some trucks between model year 2009 and 2012.

    Not all clunk. However, I am not sure if all trucks have sloppy transmissions, or some owners standards for quality are not the same. In my truck (2011) the transmission is "sloppy" and the AFM isn't a smooth transition either. Five different dealers have stated "You have the latest software".

    Your post was a "copy and paste" from a poster who used to post called "string" who should have never purchsed his truck in the first place. FYI-he got rid of the truck and went to a Honda Accord "Crosstour". Think about it.....
  • keithringkeithring Posts: 1
    I have a babied, garage kept 2002 Silverado 1500 4.8 Auto with 78k miles, never towed or plowed with it. Noticed it shifting a bit hard yesterday for the first time, this morning it really slammed and now I have no reverse and it is obviously messed up. Common for this year model? Ideas on cause?
  • obyoneobyone Posts: 8,065
    When was the last time you serviced the transmission?
  • rhlippincottrhlippincott Posts: 1
    edited August 2013
    i recently found a vacuum line coming off the top of my transmission with about 2 feet of vacuum hose but it isn't connected to anything don't see where it could possibly connect to does anyone have any idea,hesitates when shifting then jerks into gear.
  • aygee99aygee99 Posts: 1
    I have a 99 GMC Sierra.. when I stand outside the truck and turn the key to start it, it feels like the truck jumps forward. It doesn't move because it's in park but i am curious if this would be a transmission issue or something else??? Thanks in advance for any help with this...
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