2009 Sonata & Cruise Control Auto Trans Problem

2009 Sonata w/i4 Engine & Automatic Transmission problem when using Cruise:
Problem: The car will not stay in 5th gear with the torque converter
locked up when encountering the slightest incline while the cruise control is activated. Instead, the car will 5-4 shift, unlock the converter, go awhile, do a 4-5 shift, then do a 5-4 shift, so on and so forth. This is an undesired operation of the engine/transmission ONLY while the cruise control is activated. This has happen on eight of the 2009 Sonata's I have experimented with.
If the cruise control is OFF and you are just using the gas pedal, the trans will stay in 5th gear, and the torque converter will stay locked, on even bigger hills, and you can even accellerate gently without the transmission doing a downshift. This is the desired operation of the engine/trans that should also happen when the cruise control is enabled.
I have asked the dealer to fix this problem so the the cruise control operation of the transmission/engine will more closely pattern itself to non-cruise control operation. They say that they cannot because Hyundai USA has not released a software upgrade to fix the problem even though the vehicle is a one model year old and the 2010's are programed the same.
If this is happening to you, find it irritating and fuel inefficient, and you would like it fixed, I encourage you to inform your dealer and to call Hyundai USA customer service at 800-633-5151 and make your wishes known. (Their phone number & address are at http://www.hyundaiusa.com located under the "about Hyundai Tab" - "Contact us"). I have already made their engineering dept well aware of this problem.
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My 2008 Elantra does the same thing. I assume that it is the cruise control's effort to maintain the set speed.
---MIKE---

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Sjtcar wrote:

was an early production model. Had dealer do a TCM Calibration Update (TSB 09-AT-005) and that improved the situation. Have dealer check to see if you need to have that update.
Larry
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Larry W wrote:

Just checked the TSB. It was for the V6 only. Sorry for the misinformation.
Larry
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On Fri, 11 Sep 2009 11:42:08 -0700 (PDT), Sjtcar
I found the solution was to move the auto shifter to the right when you were at the correct speed and gear. This way the trans will not shift up/down until the shifter is returned to the left (or you manually shift down/up by using the shift-o-matic (don't have my manual in front of me so I think it is called this).

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This is not so much a solution as an intermediate workaround. The torque converter will still unlock using the "Sportmatic" method of locking into 5th gear. Also, by defination, the cruise control is not working correctly according to page 94 of the owners manual. This is why I would like Hyundai to issue a software upgrade that would make the cruise control operation mirror the non- cruise control operation of the engine/transmission shifting pattern.
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Indeed, the way you describe the issue makes it seem like the cruise control is operating as programmed. Without any programming changes being released by Hyundai, there's little any dealer can do to change this. In that sense, you're on the right track to achieving a resolution to the issue. Whether Hyundai issues a change depends on whether the engineers believe that making the change will adversely affect the cruise operation and whether Hyundai believes the benefits of the change outweigh the consequences.
I don't recall any cruise complaints on this model, so I haven't been experimenting with it's operation. At what speed(s) does this issue occur?
On the other hand, I just read the cruise control portion of section one owner's manual and fail to see what part of the description is in disagreement with the manner of operation you describe. Can you point me more specifically to which portion of the description you feel the operation fails to satisfy?
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On Fri, 11 Sep 2009 11:42:08 -0700 (PDT), Sjtcar
I found this irritating also. It was suggested (and it works rather well) to move the auto stick to the right. When in this position the trans will not shift up or down until the shifter is moved back to the left.
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Kent Jones wrote:

"move the auto stick to the right"
Do you mean shift into a lower gear?
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I don't know about the 4, but on the 6 the transmission goes into manual mode by pushing the stick to the right. It will only up or down shift if the speed is far out of tolerance, like first gear at 5000 RPM
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Ed Pawlowski wrote:

Oh yeah that's right, I recall that now. Well the Mrs drives the thing 99.9% of the time - it's hers. I'm happy driving my GMC Sierra.
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No. Moving the stick to the right puts the auto trans into the manual gate mode (see page 9 of the manual - Sports Mode) where you can manually shift up or down (with some limits).
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