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1999 E320 w/118K
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328 Posts
Discussion Starter #1
Cruise control works fine, but, had an unusual experience recently. Live in mountains. Reached top of mountain and as I began the descent, cruise control caused the transmission to downshift into 3rd to slow the car down. Once on level grade, the transmission was stuck in 3rd even after turning off the cruise control. I had to pull off the road, shut down the engine, restart and then all was well again.
Now afraid to use the cruise control for fear of a repeat performance. Bad cruise control?????
 

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2002 E55 AMG Sedan
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1,159 Posts
It's normal. Cruise control will downshift the transmission just to try and keep your set speed. Your transmission isn't stuck in third gear either. If you slowed down on your own and sped up again it would have shifted normal.

This happens on my car too but since I have the +/- shifter all I have to do is click the shifter over to + and it will upshift. You have the older shifter so that method doesn't work for you.
 

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1999 E320 w/118K
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328 Posts
Discussion Starter #3
Thanks for the info!! Relieved that I do not have a problem with the CC or the transmission!!
 

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E320/E250 Bluetec Ford F350 6.7l
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36,318 Posts
You have
"hill descent" working with CC and
"transmission adaptation" or learning who remembers your driving style and adapts gear changes.
When I used to live in CA, we often would drive up to Berkeley hills for dog walking and on my way down I was manually downshifting to 2nd for less stress with braking.
The 3 miles drive was enough for the transmission to reset adaptations and keep low gears for long for next 10 miles.
What made it changing the program faster was "spirited takeoff" at next green lights.
 
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