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Chevy Silverado and GMC Sierra Transmission Problems



  • OK, I will do that.

    Thank You,

  • galvezfjgalvezfj Posts: 12
    Hello Sarah, I recently purchased a new 2012 1500 siverado Lt 4x4. The truck does the same thing as some of these other owners. I got the truck with 2 miles on it and the first time it jerked out of 1st gear i thought i did something wrong. the dealer said not to worry about it. I have had the truck for 10 days now with less then 400 miles on it and this issue is still there. Reading about the transmission issues these trucks are having do I need to take the truck back to the dealer.
  • jjacksjjacks Posts: 16
    edited March 2012
    Okay, so I decided I'd buy another GMC for a tax write off in December. Looking for a deal, I found a 2011, but my dealer didn't want to go get it since it was about 130 miles out. So I made a deal over the phone and went and got it, whilst trading in my 2008 that had the preverbial propeller shaft slip yoke clunk. That clunk, at least I knew what it was. SO, running a bit late, hustled out the door, cranked up, hit the highway.....hmmm...thinks to self....this thing must have some flat spots on the tires from sitting a long time. Dealer called and I wasn't 10 miles down the road and they forgot some paperwork, had to turn back, documented the vibration. Fast all the way back, still vibrating! Finally take into local dealer at 2500 miles. First chance I had, and this is the list I took them: (yes, i printed out a list)

    1. Constant vibration. Gets worse with heat. Had vibration since drove off the lot.
    2. Excessive ring/pinion lash. Rear-end whines on deceleration. Needs ring and pinion.
    3. Poor throttle response. Especially at low speeds under 10 mph. Likely related to excessive drive train slack. Check throttle position sensor.
    4. Torque converter feels like it stays locked up to long and at very slow speeds on deceleration, the transmission downshifts like it is being downshifted manually. Shift points do not match appropriate speeds to make the proper shift.
    5. Upon cranking, engine revs excessively to around 1,800-2,000 rpm. To high.
    6. Whenever you first crank it up, and put it in a forward gear and reach about 5 mph, there is some kind of movement in the pedals/column. It’s like the adjustable pedal motor gets a touch of voltage for a split second. Irritating as hell.
    7. Poor engine oil pressure. I assume this is for gas mileage purposes. It’s not helping.

    The drive-train slack is severely excessive for any kind of new vehicle. Full disclosure, I am knowledgeable with high and low performance engines, and have modified, built, and rebuilt gas and diesel engines. I have also been in my fair share of transmissions. And lastly, I’ve been in several GM rear ends, Ford third members, and heavy equipment planetaries and third members. Set up lash, etc.
    In summary, and as my service records show, I don’t bring anything in like ‘wind noise’ or anything like that. When I bring something in, it has a legitimate problem. This truck has problems.

    One thing you will notice is that I didn't bring up the AFM issue. I'd be happy if I could get the vibration at 20-30 fixed, as it is the same vibration at 55-75. AFM just makes it a bit worse. GM, in their infinite wisdom, came up with the AFM for better mileage. One thing they can never do is "make it seamless". They can make 'cushier' cab mounts and such to dampen the imbalance, but it is physically impossible to rebalance an out of balance engine without turning the other 4 cylinders back on. You will feel it more with lower ratio rears, like 3.73-4.10 -vs- 3.42 -3.08 because of the 'dampening effect' of the higher ratios. What GM needs to do if they want the AFM concept is to drop ONE cylinder and rotate across the firing order to lessen the imbalance. That would help. Now, on to the 6 speed tranny. No doubt a mileage idea also. You can thank your government and the 15% enthanol mandate for the reduction in mileage that GM would like to compensate back with the pathetic software programming for this transmission. In theory, it is programmed to achieve the federal mandates. In reality, the thing sucks. I was told by the mechanic at my local dealer who was riding along proclaiming my tires were bad that the transmission will only 'live' this way. Uh huh, a fool would think that. It won't live as long the way they are set up.

    SO, back to ol shakey. Been to dealer 8 times I think. 2 service tickets. 2 new tires. Road force completed. Hey, guess what, I said it wasn't the tires....AND IT'S NOT. Okay, since I am a 'mechanic', but it is not my paycheck trade, I said look at the differential. I mean, the damn thing is whining...especially on a slight decline coast 50-40 mph. When something's talking, maybe you should listen. SO, here's the joke of the day. My local dealer mechanic said he checked the ring/pinion backlash. I said "what was it?",,answer .0045. That would be fine and dandy, but I have yet to see a contraption that allows this measurement without the rear cover being taken off, and it wasn't. He did the ol 'feel job' on the yoke, and got .0045. HAHA.

    But here's the kicker. The service manager with the mechanic standing there said, and I quote "GM will not let us tear into anything until it has 5,000 miles on it". Now I have 5,200 miles of vibration behind me and we're about to either get past the bs or get with the certified mail. I could fix the thing myself, and I may have to, but if it comes to that, somebody at GM will get the problem parts sent to them, possibly along with something my great dane leaves behind in the yard.

    What I suspect it is, is a combination of excessive ring/pinion lash combined with a mis-machined carrier that is allowing the spider gears to 'climb' the axle gears. I don't dare take the cover off yet, or they'll say 'oops, out of warranty bud'.

    If anybody has a clue was to what causes #6 above, please reply. Of course they didn't do anything.

    Ok chuck, what say you?
  • gmcustsvcsarahgmcustsvcsarah Posts: 1,964
    Good morning galvezfj,

    Does your Silverado have a 6-speed transmission?

    GM Customer Service
  • gmcustsvcsarahgmcustsvcsarah Posts: 1,964

    I understand that you have quite a bit of mechanical expertise and are very comfortable with working with vehicles. I see that the main unresolved issue that you've been in repeatedly for and are not satisfied that your dealership did their best to diagnose is the vibration that you've been experiencing since purchasing the vehicle. If you would like to set up a Service Request with my department to have this documented further, as well as followed up on to the best of our abilities, please send us an email at (include your name/Edmunds username, phone and address, the last 8 of your VIN and current mileage, and the name of your involved dealership).

    All the best,
    GM Customer Service
  • chuck1919chuck1919 Posts: 176
    #4,5.6.and 7 listed in the points above are either your opinion or the way the truck is programmed per your point about EPA mandates and gas mpg.

    In my view you probably shouldn't bought the vehicle.

    Other than that, I sincerely hope you get the vehicle fixed where you can live with it.
  • galvezfjgalvezfj Posts: 12
    Yes it is a 5.3 lt. 6 speed automatic transmission. Z71 4x4.
  • gmcustsvcsarahgmcustsvcsarah Posts: 1,964
    Hello again galvezfj,

    The 6 speed transmission uses adaptive shift controls. Adaptive shift controls continually compare key shift parameters to pre-programmed ideal shifts stored in the transmissions computer. The transmission constantly makes adjustments to improve vehicle performance according to how the vehicle is being used, such as with a heavy load or when temperature changes.

    During this adaptive shift control process, shifting might feel different as the transmission determines the best settings. When temperatures are very cold, the Allison Transmission and Hydra-Matic 6-Speed transmission's gear shifting could be delayed providing more stable shifts until the engine warms up. Shifts could be more noticeable with a cold transmission. This difference in shifting is normal.

    The idea behind the design of the adaptive shift control process was to maximize fuel economy. You can certainly have your vehicle checked into by your dealership if you like, and please do keep us posted! I had just wanted to provide this information for you to know what may be going on if your dealership says that the vehicle is operating normally.

    GM Customer Service
  • galvezfjgalvezfj Posts: 12
    edited March 2012
    Thank you for this information Sarah,

    This is my first chevy all my other vehicles are toyotas. 2 tacomas and a sequoia. I really like this truck since it is fully loaded. I will take it in to make sure everything is functioning normal. Its just when you take off from a complete stop the truck shift hard and jerks your head back pretty hard. never had anything like this happen in any other vehicle i own. thank you
  • jjacksjjacks Posts: 16
    Hey chuck, your view of me not buying the 'problem' may be right. Problem is, I've always bought chevy or gmc, not one ford, dodge, nissan, nor toyota.

    4,5,6,7 are facts, bud. I'm a mechanic. #6 is something weird,,,gonna take a bit to nail it down, but it's inexcusable nontheless. #4 = when you're idling around the neighborhood about 10 mph and you slow to turn in your driveway and it feels like you just got rear-ended,,,,that ain't adaptive shifting. #5 = is going to cause premature crank damage, possibly. Just what is to high, chuck, a 3,000 rpm start, aw hell, how about 5,000? It has a throttle body, tps, drive-by- wire problem. When you have to wait for it to come back down so you can put it in gear, it's to damn high, got it? It's not constant either, just random. #7 20 psi may be enough now, but what you gonna have at 100,000 miles?

    I bought a '87 with tbi that had a burnt valve and almost 300,000 miles for a few hundred bucks. I pulled one head, lapped in one valve, put it back together and put another 200,000 miles on it. It got better mileage and ran smoother, cranked better, than this 2011 'gem'.
  • gmcustsvcsarahgmcustsvcsarah Posts: 1,964
    I'm glad to get information out when I can! Hope all goes well when you go in to get things checked out.

    GM Customer Service
  • Hey I'm back! Went to three different dealers, got the same runaround, "It's Normal" for that transmission. I was told it's a learning transmission, yeah right......I'm the one learning to put up with the horrible shifting problems. Received a call from district manager, he tried for 45 minutes to convince me that I should accept the poor performance of the truck. It's set up like that to improve gas mileage. I am test driving a 2012 this week to see if it shifts any different, if not, I guess I'll have to pursue the "Lemon Law" route!
  • jjacksjjacks Posts: 16

    I went by the dealer again today. The service manager told me that his GM rep was on vacation this week and would be back monday. I suspect you'll be getting an email next monday afternoon.

  • dave_g3dave_g3 Posts: 1
    Thank you jjacks for posting this. I have been having the same problems with #1, #4 & #6. I have the Chevrolet Silverado 1500 LT 5.3L 6 Speed automatic 4X4 Single Cab. I also took my vehicle to the dealer not long after buying it and got no resolution. I really dislike the hard downshifting, the unintended accelleration while stopping, and the constant shaking at idle. I also feel a sort of "clunk" after I put it in drive and start rolling. It only happens after the vehicle has been sitting for a while.

    What say you gmcustsvcsarah? What can I do to get this fixed?
  • chuck1chuck1 Posts: 1,405
    edited April 2012
    You may be a mechanic but these motors are not circa 1970. They don't need alot of oil pressure to operate properly. Again, most of these issues are your opinions. It seems foolish to think that GM would engineer these motors with an oil issue waiting to happen when they will be fixed (in an event of a failure) at GM's expense. The high RPM start is for a split second or two at startup.

    I am familiar with all the issues you mentioned, however I disagree with the "outcomes" (or even if they are actual problems) that you think they are. NONE will leave you stranded. And without going in to the ECM you will not be able to fix them, IMHO.

    Again-I am not a GM employee or paid by anyone.
  • jjacksjjacks Posts: 16
    Is that all you got Chuck? None will leave me stranded? Yeah, I know that, never said they would. Now, put down your pom poms for second. The oil pressure is marginal. After you have seen the internals of DOZENS of different types of engines, including 500+ci procharged engines, you come on back to me and school me about proper oiling and clearances. The way it is now, Im confident it will last past warranty expiry.

    Those same foolish GM engineers brought you the diesel engines (converted [non-permissible content removed] gas engines) in the early 80's, those fabled early 700r4's, and this piss-poor non learning crap shifting 6 speed auto. Contrary to popular belief, these transmissions don't 'learn'. Input is taken from the various relevant sensors and compared to a shifting map, which in turn picks the outcome. Computers don't learn, they follow programming. These transmissions follow a programmed map. It is the map that sucks. But, from the get go, I said I'd deal with the transmission last.

    Whining differentials and vibrations. No, they won't leave me stranded either. That's not the point. The point is that everyone buying a new GM product shouldn't have to put up with this junk you want to pawn off as acceptable. It's not.

    Opinions huh? I bet if you drove this vibrating whining 5,200 mile POS for a couple hundred miles, you'd change your tune. Furthermore, everyday from now on, I want you to push down your accelerator pedal about half way and then crank your vehicle. Only for a second or two. Remember, you may have to wait a bit before you slam it in gear. Or not. I'm sure you won't be stranded while still in warranty.

    My 2008 with the identical 5.3 didn't have this low of oil pressure. Maybe it's the gauge. Of course it had the 4 speed OD and shifted properly. And it didn't vibrate your teeth out either.

    I'm curious, exactly what do you drive?
  • chuck1chuck1 Posts: 1,405
    edited April 2012
    I have two cars. Both of which I bought new. The first one is a 2007 Honda Accord EX-L 4 cylinder. It's been pretty much flawless. The first "repair" was a bad central airbag controller. The repair was $600.00 and I called American Honda and they and the dealer knocked off about 35% off the repair. Talk about trying to build loyalty. This with a car that had 99,000 miles on it with no extended warranty.

    The second is a 2011 Chevrolet Silverado Crew Cab 1500 -5.3LT w/the tow and chrome pkg. It currently has 13,000 miles on it. It tows my 5,000 pound travel trailer satisfactory. Yes, it has the power train "clunks". Yes, it's 20 PSI oil pressure at idle. It also rides very smooth and I can CONSISTENTLY get 20mpg on the highway at speeds not exceeding 70ish with the AFM going to 4 cylinders.. It's been to Salt Lake City, UT twice and once to Sedona, AZ from Southern California.
  • jjacksjjacks Posts: 16
    Well that helps explain a lot. First off, you berate anyone who has a problem that 'you' haven't had for no apparent reason, but turnaround and play the hypocrite card for asking Honda to pony up a discount on something that was well out of warranty. Cheapskate, why didn't you just deal with it. That is what you've been telling everyone on this forum. Second, you're in Cali. 'Nuff said. Third, you're not a mechanic and you wouldn't know what a powdered metal rod was if it hit you in the face. Google it. Fourth, you don't know what the proper oiling requirements are. Fifth, your truck doesn't vibrate and whine, mine and others do. Sixth, apparently you have no clue that GM subs out the differentials to American Axle, so it's not a GM product. Seventh, my truck wouldn't get 20 mpg if I shoved it off a cliff, but yet I had an old gen LT1 in a corvette that would get 30 mpg running 70 all day long. 30. And lastly, you probably don't know that GM makes special packages for the Ark-La-Tex area because that's where they sell 3 out of 4 trucks domestically.

    I've always bought GM. I'm a GM man, but I will not sit here and make excuses for junk quality.
  • chuck1chuck1 Posts: 1,405
    Yea, I am in California and am quite aware that all cars/trucks are made of parts from various suppliers. Your the one saying it's not getting enough oil as designed by the manufacturer. So apparently, you know more because your a mechanic than the engineers that design them.

    I don't believe for a minute that LT1 motor got 30mpg in a corvette.

    I am quite aware that GM makes special packages. Those very packages. are available nation-wide but GM gives them different names in every region.
  • jjacksjjacks Posts: 16
    No Chuck, I didn't say it wasn't getting enough oil. I said the oil pressure is marginal. You see, if you were mechanically inclined you would know that pressure readings and volumes are not the same. It may be receiving ample volume without the pressure. It could be by design, or it could be machined surface clearance out of tolerance by a mere .001 of an inch, which would be .0005 inopposite. Who knows. The point is less drag. Less drag means more mpg, get it? Of course that's the cheapskate way to get mpg, those big brained engineers could improve the windage of the crankshaft, increase the oil psi and improve mpg and reliability. But that would be more expensive than a spring that regulates pressure.

    I don't want to mislead you Chuck, I bought the 'vette new in 1994. It got about 26 mpg from the factory. I increased the fuel pressure 3 psi and reprogrammed the computer. Then it got the 30 mpg. So much for the 'engineered designed fuel and timing maps'.

    I've got a '72 vette in my garage right now. It's getting a complete resto and a LS3 mated to a T56 6spd. It should get 27 mpg. If only some GM engineers could come over and tell me it won't
  • babbs3babbs3 Posts: 50
    Hey are right on with every point! When a person has a car that doesn't have tranny problems they think the rest of us are making it up. They also say "oh all mfg. have problems with transmissions.huh? Neither ford or GM will fess up to buying poorly built trans. The reason is...there percent of bad ones aren't high enough and no one has died (there have been accidents though). Chuck you know your cars and you certainly like GM but wrong is wrong. So it is refreshing to point out the obvious...quality is important.
  • chuck1chuck1 Posts: 1,405
    I don't think those with problems are making them up. These power trains ARE NOT the smoothest.

    However, my issue is because some are upset (as I would be too) is the half-truths or sometimes outright lies that get put on this forum.

    I guess it's their way of getting "revenge".

    I will continue to do the "half truth alerts".
  • jjacksjjacks Posts: 16
    Chuck boy, if you are saying people are lying, including myself, then maybe you should carry your little self on over here and I'll make a believer out of you. You're not a mechanic and just because you got lucky and got a decent one, that doesn't mean everybody else is out for revenge and spreading lies. Pathetic.
  • jjacksjjacks Posts: 16
    Babbs, I think you have me and chuck confused. I'm the chevy man without pom poms, Chuck is the honda guy with pom poms. Thanks
  • I have a 2009 with a 5.3l, 6speed, 4x4, 3.42 rear end. It came with the Z71 package and has the 18" wheels. I have been having problems with the transmission and I am wondering if anyone else has experience similar problems. 55k miles.
    Here is what happens.
    When I pull away from a stop, it shifts very, very quickly (under normal driving, when I hammer on it, this doesn't happen) down into 2nd and third goes to 2nd before I even make it through the light. So, when I want to then bring it up to speed, it is already locked down into usually 3rd and wants to stay there unless I go past probably 3/4 throttle, at which point it jumps down violently to what feels like 1st. Seems like it is tuned very, very aggressively for mileage. Very, very annoying as it does that all the neighborhood/slow speed city driving really stinks. Tranny is very confused. If I put it into tow/haul, it stays in gear much longer and there is no issue. Seems like it might be tuned for an engine with much more torque or a 3.73 or 4.10 rear end.

    2nd. When slightly rolling (1mph or less) and then trying to accelerate, there is a slight 1/2 second delay, then the power kicks in and everyone's head jerks back. I have to be very, very, very gently on the pedal and feather it through this until the engine/power engages. This seems like it might be a throttle issue or something to do with the fuel delivery. Does this truck have a throttle cable, or is it electronic?

    3rd. Problem. Towing. Under hard acceleration (not w.o.t., but well past 3/4 throttle) and towing 2k--4K trailer, there are multiple times where the tranny "jumps" or slips in between 2nd-3, 3-4, and 4-5. Engine revs slightly and it jerks into gear. Again...seems confused.

    I have had this truck to the dealer for warranty work on tranny. There are no codes. They could find nothing. I explained everything to my dealer as I have in this post. It is due to go in again. I checked tsb's and couldn't find any that seemed to be related to the issues I am having. HELP

    2 times ago at my dealership they gave me a 2012 as a loaner. Totally different truck even though it had the same engine and the same tranny and the same rearend (3.42). Clearly the 2009 needs an updated tune , but GM refuses to both acknowledge this and act on it. Help. Somebody. Please.
  • I have posted several times about my 2011 that has the same transmission problems. Returned to three different dealers and they all say the same thing "it's normal for the transmission to be erratic because it is tuned to save gas". Funny, I went from a Yukon with a 4 speed automatic to this 6 speed and it was never disclosed to me that I would hate driving this new truck! The gas mileage increase in minimal, maybe a half a mile to the gallon. GM, PLEASE FIX MY TRANSMISSION, for $50,000 the truck should be a dream to drive!
  • have the same issues with my 06 and i'm with the fire dept, they said the same thing to me. it's normal ...sorry to say good luck. i complained and it didn't get me any where
  • chuck1chuck1 Posts: 1,405
    edited April 2012
    "When I pull away from a stop, it shifts very, very quickly "

    The first gear in the 6 speed is a VERY SHORT gear. It will shift from 1st very quickly. That's what it is supposed to do.

    "3rd. Problem. Towing. Under hard acceleration (not w.o.t., but well past 3/4 throttle) and towing 2k--4K trailer, there are multiple times where the tranny "jumps" or slips in between 2nd-3, 3-4, and 4-5. Engine revs slightly and it jerks into gear. Again...seems confused."

    Use "tow-haul mode". It will hold on to gears longer. Under hard accelerating, more often than not it will downshift more than one gear.

    "Seems like it is tuned very, very aggressively for mileage."

    Yes, it is.

    It seems a longer test drive would have been in order for you. You shouldn't have bought the truck.

    Except for the "JERK" you are describing, the truck is acting exactly as it is designed.
  • jjacksjjacks Posts: 16
    Chuck, once again, you aren't a mechanic, are you? The short gear ratio has nothing to do with the shift points as he described. Most likely he is describing a downshift from 3rd to 2nd, as those ratios are very close to a 2nd to 1st in a turbo 350 transmission. Or in the alternative, an upshift from 2nd to 3rd. My transmission is in 3rd gear at 10 mph. The 'cant seem to figure out what gear to shift to' while towing is a flaw. My transmission has had some off the wall excessively high shift points under moderate acceleration.

    "You shouldn't have bought the truck". No, GM should fix their junk, period. If the same transmission acts right in a 2012 vs 2009, 10 etc, then there obviously is a software/hardware/hardparts issue. Deal with it.

    Sarah, if you are reading this, I've been back by the dealer twice, and supposedly the GM rep is due by the dealer next week. There has been no decision on the howling differential and vibrations so far. My patience is wearing thin, and if it comes to it, I will tear into it myself. If I do, it will be made public via website or youtube or wherever. i know ive been there at least 10 times so far. Ridiculous.
  • chuck1chuck1 Posts: 1,405
    edited April 2012
    What he is describing to me is normal operation, regardless of your interpretation, thoughts, occupation and opinions, etc.
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