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Discussion Starter #1
Hi, I am Rob Penn,
I have a 2007 Solstice. I have been having a problem with the transmission. For no reason on level roads without any extra pressure it will downshift. The transmission shifts very smooth and has plenty of power with no slipping. I can shift into neutral, let it coast for a short distance, shift back into drive and most of the time it will shift up. It will not last very long until it downshifts again. Usually this will happen after I have been driving for 30 minutes to 1 hour. There is no faults showing when the dealer runs a computer check.
Has anyone else experienced this problem.
 

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Hi Rob,

Welcome to the forum. I hope you can find a solution to your problem.

I have not heard of that particular problem. There is a similar problem with hard downshifts that is usually triggered by failed camshaft timing avtuator solenoids, but your specific issue does not, on the surface, seem to actually be related to that.

Does this happen every time you drive the car for that long? Does it always reoccur during that drive? How long does the car have to cool down before it doesn't happen immediately?
 

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Hi Rob,

Welcome to the forum. I hope you can find a solution to your problem.

I have not heard of that particular problem. There is a similar problem with hard downshifts that is usually triggered by failed camshaft timing avtuator solenoids, but your specific issue does not, on the surface, seem to actually be related to that.

Does this happen every time you drive the car for that long? Does it always reoccur during that drive? How long does the car have to cool down before it doesn't happen immediately?
H I John.
Thanks for your reply. It does not always happen every time I drive the car. It does not happen as often when the weather is cooler. I live in Kentucky, therefore we have temperature changes. How long does it have to cool down I do not know because I usually return home, park the car and maybe the next day drive it again. The downshifts is not hard and aggressive, it is a smooth shift. Once it downshifts it will continue to do so until I get home. Sometimes it will get to 4th gear and stay there, not shifting into 5th. 3rd gear is about al low as it downshifts until I stop. On take off it will start in 1st and shift up to 3rd or 4th and stay there.
 

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H I John.
Thanks for your reply. It does not always happen every time I drive the car. It does not happen as often when the weather is cooler. I live in Kentucky, therefore we have temperature changes. How long does it have to cool down I do not know because I usually return home, park the car and maybe the next day drive it again. The downshifts is not hard and aggressive, it is a smooth shift. Once it downshifts it will continue to do so until I get home. Sometimes it will get to 4th gear and stay there, not shifting into 5th. 3rd gear is about al low as it downshifts until I stop. On take off it will start in 1st and shift up to 3rd or 4th and stay there.
Good information. I will do some browsing through the service manuals tonight and let you know what I find.
 

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The most likely problem I can see this being is a problem in the shifter. As far as I have been able to determine, any other fault would trigger a code and you would get a MIL.

Have you tried shifting into either 4 or I instead of N when this happens?

The shifter is really just an electrical switch or, technicaly, four switches. Those switches are switched on and off in a pattern that tells the TCM what you want the transmission to do based on the position of the shifter. Looking at the pattern of the switches there is one that, if switched on when it shouldn't, could keep the transmission in the lower gears.

I asked about 4 and I because there could be a problem with actuating the various switches, and that problem may be limited to the D position. Its kind of a long shot, but is possible.

To definitively troubleshoot this problem you may need a scanner (Tech2 or equivalent) that can read the actual systems. A code scanner won't do it, although it would be worth having the ECM read to see if there is a pending code of some kind that just hasn't lit the MIL.

You could also disassemble the shifter assembly to see if you can find something, but that is really speculative. Another possibility is a flaky connector, so just for fun you could unplug and re-plug the TCM. Doing the same with the connector on the shifter would also be worthwhile but some disassembly will be needed to get to it.

A further possibility is a heat-related problem with the TCM. I don't know what to do about that one beyond replacing it.
 

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Discussion Starter #8
Thanks, this is some ideas that I had not thought of. I was thinking electronic because the transmission shifts very smooth and is strong with no slipping. I have very limited electronics knowledge so thanks for the ideas. I will keep you informed if any thing works or not works.
 
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