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2012 Lacrosse late shift 1st+2nd
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steveb
New User
Sep 3, 2012, 7:58 AM
Post #1 of 4
(1537 views)
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2012 Lacrosse late shift 1st+2nd
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I am a retired ASE Master Tech with 30 years exerience including Trans Overhauls. I just bought a new 2012 Buick Lacrosse 6cyl,6 speed automatic 100 miles on it. Under light acceleration it will not shift out of 1st or2nd until 4500-5500 RPM unless I have my foot almost completely off the throttle. With the same amount of throttle my GMC Sierra shifts at 2300 RPM. Buick says this is normal I say not even close and it is probably aprogramming error they don't want to change because it will mess up their EPA mileage and emissions certifications. I researched this on the internet and it seems to be a common complaint. Others have tried to get Buick to help with no success.Iwas wondering if anyone knows of any TSB's on this or if a Trans shop could reprogram my shift points. thanks for your help!
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Sep 3, 2012, 8:21 AM
Post #2 of 4
(1519 views)
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Re: 2012 Lacrosse late shift 1st+2nd
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100 miles on it NEW! Hey if you are into the biz you know you shouldn't mess with anything under 100% warranty. I see no harm in checking for plain old vacuum hose not hooked up or anything sensing actual intake manifold vacuum which by now is probably converted to an electric signal or any connections sensing throttle position, VSS (speed sensor on trans) or anything that is obvious and not hooked up.
This is bull. I can't believe it was intended out of six speeds to wait for such high RPM for the 3rd. What's worse is a run around already with any dealer that will not help you. Might be early for TSBs or a reason for this.
If you acquired this at an actual dealership I'd go back and test drive another exact drivetrain one just for a test. If you mess with it even if more qualified and they know it you may own the problem,
Tom
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Hammer Time
Ultimate Carjunky
/ Moderator
Sep 3, 2012, 8:53 AM
Post #3 of 4
(1511 views)
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Re: 2012 Lacrosse late shift 1st+2nd
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This is the only TSB I find close.
INFORMATION
Bulletin No.: 01-07-30-042G
Date: September 22, 2011
Subject: Information on 2-3 Upshift or 3-2 Downshift Clunk Noise Models:
2012 and Prior GM Passenger Cars and Light Duty Trucks
Equipped with 4L60-E, 4L65-E or 4L70-E Automatic Transmission (RPOs M30, M32, M70) Supercede:
This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 01-07-30-042F (Section 07 - Transmission/Transaxle). Important
For 2005 model year fullsize utilities and pickups, refer to Corporate Bulletin Number 05-07-30-012.
Some vehicles may exhibit a clunk noise that can be heard on a 2-3 upshift or a 3-2 downshift.
During a 2-3 upshift, the 2-4 band is released and the 3-4 clutch is applied. The timing of this shift can cause a momentary torque reversal of the output shaft that results in a clunk noise. This same torque reversal can also occur on a 3-2 downshift when the 3-4 clutch is released and the 2-4 band applied. This condition may be worse on a 4-wheel drive vehicle due to the additional tolerances in the transfer case.
This is a normal condition. No repairs should be attempted.
You can't change the way GM engineered that vehicle. This is why vehicles are road tested and ratings are published. I suggest you look for a different vehicle if you're not happy with this one.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Discretesignals
Ultimate Carjunky
/ Moderator
Sep 3, 2012, 5:48 PM
Post #4 of 4
(1487 views)
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Re: 2012 Lacrosse late shift 1st+2nd
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This a mystery to me why they haven't come out with an update for that mysterious shift schedule they designed. Obviously it isn't a mechanical or electrical problem because the PCM would be flagging some sort of shift timing, ss circuit, or gear ratio code. Has to be software. Techs probably have their hands tied because they really can't do anything on the software level besides updates they receive from GM.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Sep 3, 2012, 5:49 PM)
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