Rough shifting at altitude


#1

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?


#2

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.


#3

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