2011 gmc sierra trans issues?

84plowtruck

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I have a 11 gmc sierra w the 5.3, and 6 sp trans. Having driveline noise and clunking in rear. I also have this problem while slowing to a stop as the transmission downshifts it surges the vehicle forward causing a dangerous situation. I was also stopped at a light last week and let off the brake to go, usually starts to move on its own but didn't. It was almost like it was in park, then when i pressed the gas nothing, then a little more gas and loud clank from rear and it took off. Very disapponted with this truck sorry to say. Always been a gm person but never any of these issues. Any help would be appreciated. Thanks in advance,
Travis
 
I have had the same problem with my truck. I bought it a couple months ago and I am taking it in on Thursday to see if they can figure it out. I thought it was because the truck came with a Rocky Ridge package (6in lift with 35's) and it had somehting to do with the lift. I will let you know what they say.
 
That would be great thank you. As you well know this is very frustrating, i want to love this truck but its making it very difficult.
 
I have a 2009 Sierra and have had the same problems. To me it feels like the Engine computer software is out of whack. (We have this issue on nearly every new model Toyota that comes out. I would in Engineering for Toyota and DENSO) However, when I took mine in they said there was a service bulletin and that the rear end required some "additive". They put it in and the issue went away. However, this was not a permanent fix and the issue is going on again.

This problem has been my biggest disappointment with my truck. It is a design problem that never should have been released into Mass Production. I have owned several GM's 1 Ford and a couple Toyota's. I can not believe this issue has not been fixed.
 
Well when I took my truck in to have it looked at for this problem OF COURSE they could not find anything. They hooked it the trans up to a cpu and looked for any codes and nothing showed up. As soon as I left it happened to me and they had it on 2 test drives and it never happpened to them. I told them how many people had the same problem on the forum and they said they will look into it further. I am going to write the company also and find out what the problem is. I wont hold my breath for a speedy reply.
 
I can make mine do this at anytime. My garage first did not find anything. It was a later visit that they found the service bulletin.
 
I bet you never drove a 6 sp trans before? Let alone a vehicle with drive-by-wire (no mechanical connection with the engine and gas pedal). They do take some getting used to over a typical 4-sp because its shifting more often and to improve fuel economy its in 6th gear early. The drive-by-wire has a delay if when you step on the gas and when it gets the signal. That's to prevent abuse of the transmission by delaying torque application.

I admit I had trouble getting used to the 6 sp also as well as the drive-by-wire. You have to change you driving style.
 
i will agree with 84plowtruck that SOME times when slowing down around 20 mph with my foot on the brake the trans surges the vehicle forward when down shifting. This makes me have to step on the brake harder. Also not a fan of this trans in tow mode becaues the trans will down shift while coasting down a hill sometimes bringing my rpms up to 5 k.

And ya i will get a clunk every once in a while but if you drive GM tks then you know there will ALWAYS be a clunk and nothing will ever come of it.
 
I worked for a large state agency as a Survey tech for over 30 yrs and drove every major brand vehicle (our dept bought 90% of the vehicles solely on cost) and the trucks all clunked to some extent and more noticeable were the 4x4's. We had 6 vehicles on our GPS Survey Team when I retired, 1 GM (K2500 'burban my vehicle), 2 Fords and 3 Dodges so I got to drive them all over the years. I been driving 4x4's ever since I started working in 1972 as a surveyor on highway construction, 40 yrs I have driven 4wd vehicles (GM, Ford & Dodge) and bought my 1st new 4wd, a 1975 Chevy Blazer and have owned a GM 4wd ever since.

What I am saying is this. What one person perceives as a problem might just be the operating characteristic of the vehicle in the conditions they are operating it. Sooner or later they will become accustomed to the idiosyncrasies of the vehicle and adjust their driving style to fit it. And the fact that the dealers found nothing wrong leads me to this conclusion. Different drivers and different driving styles, seen it all the time with our work trucks. What one person complained about, others did not agree.

Mike
2010 GMC Sierra SBEB SLT Z71 All Terrain
2009 Cadillac CTS4 AWD Performance Sedan
 
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I bet you never drove a 6 sp trans before? Let alone a vehicle with drive-by-wire (no mechanical connection with the engine and gas pedal). They do take some getting used to over a typical 4-sp because its shifting more often and to improve fuel economy its in 6th gear early. The drive-by-wire has a delay if when you step on the gas and when it gets the signal. That's to prevent abuse of the transmission by delaying torque application.

I admit I had trouble getting used to the 6 sp also as well as the drive-by-wire. You have to change you driving style.

+1 I think this is what people are referring to or feeling. My Mercedes did it worse than my new 2011 GMC, which was a 7 speed. If I came to a stop quick and tried to take off right away if would have a delay and then catch and have a little jerk. I didn't really like it, but I adjusted around it.

The shifting down hills is so you don't have to ride the brake. The Allisons have a similar thing and I actually like it. Put it on cruise in tow mod and it keeps the speed down a hill. Mine does the little surge coming to a stop too if I stop rather quick. To me it feels like a quick down shift through 2-3 gears. It's minor. At least on mine.
 
Tranny probs

I agree that this issue may be a characteristic of this transmission I'

I a gm tech and I've seen these issues come up and never find any dtc codes even though u think it would store them in the PCM . How ever if u r unsatisfied with the diag please request a ride along with the tech to duplicate the issues just to make sure the tech understands what your concern is with the tranny . And also take a ride in a similar vehicle and see if it's different .
 
Thanks for all the insight I really do appreciate it. Lots of good knowledge, it may be something I have to get used to I guess.
 


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