I was just driving my 2010 Ford F-150 (automatic, 41k miles) on the highway with cruise control on. When the truck would come down one hill and begin going up the next (there are a lot of hills near me), the transmission would clunk badly enough for me to bounce out of my seat. These are pretty gentle hills, so I can't see why going uphill would be such an issue. What could cause this?
I did not have to look very far to find that this inconsistent shifting is a common issue across all models of the F-150 and transmissions used. Ford has several Technical Service Bulletins (TSB) that may cover your issue. The latest one I found is TSB 13-11-3 dated Nov. 1, 2013 and calls for your PowerTrain Control Module (PCM) and Transmission Control Module (TCM) to be reprogrammed with the latest calibrations. These updates are the result of engineers at Ford testing and adjusting their programs in response to customer complaints like yours. This should fix your problem, however, I would suggest you still have YourMechanic thoroughly test your vehicle and verify you do not have other problems and to verify your vehicle qualifies for the calibration update. After a calibration update the TSB calls for a through road test to ensure that the transmission shifting and engine work together smoothly.
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