# Rough shifting at altitude

**URL:** <https://community.cartalk.com/t/rough-shifting-at-altitude/733>\
**Category:** Maintenance/Repairs\
**Created:** [June 19, 2007, 9:43pm UTC](https://community.cartalk.com/t/rough-shifting-at-altitude/733 "2007-06-19T21:43:18Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![EllenG](https://avatars.discourse-cdn.com/v4/letter/e/97f17d/32.png) [@EllenG](https://community.cartalk.com/u/EllenG)\
**Post date:** [June 19, 2007, 9:43pm UTC](https://community.cartalk.com/t/rough-shifting-at-altitude/733/1 "2007-06-19T21:43:18Z")

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My 2000 Buick Century has 60,000 miles. When driving long distances or at higher altitudes it shifts unexpectedly and with severe jerks - both down and up-shifting. Speed and incline often aren’t obviously enough to warrant the shifts. Extended warranty expires in ten days. Since I live at sea level, how do I replicate the problem for a local mechanic? And what might be causing this?

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**Author:** ![Roadrunner](https://avatars.discourse-cdn.com/v4/letter/r/d2c977/32.png) [@Roadrunner](https://community.cartalk.com/u/Roadrunner)\
**Post date:** [June 20, 2007, 1:17am UTC](https://community.cartalk.com/t/rough-shifting-at-altitude/733/2 "2007-06-20T01:17:12Z")

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The pressure control solenoid in the transmission may be worn.

This solenoid used to be a culprit of shifting difficulties in the 2000 Buick Century. (At least it was in two posts I read)

Another one to check out could be the VSS (Vehicle Speed Sensor).

Perhaps the computer needs to be reprogrammed. Just guesses mind you.

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**Author:** ![transman618](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/transman618/32/24_2.png) [@transman618](https://community.cartalk.com/u/transman618)\
**Post date:** [June 20, 2007, 3:38am UTC](https://community.cartalk.com/t/rough-shifting-at-altitude/733/3 "2007-06-20T03:38:42Z")

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Get it scanned… One of the inputs that the computer uses in the shift strategy comes from the MAP sensor. Let a trans shop or dealer have a look. It could very well be a driveability issue and not a transmission issue.

transman