bump/thump when downshifting
#1
bump/thump when downshifting
2001 Grand caravan 39k has a bump when downshifting at about 35 mph. At times this bump is loud and will wake you up if you are trying to drive and sleep, this bump only occurs when the Od in engaged, and does not occur when I select the #3 position. The fluid is red the level is good. Any ideas, thanks.
#2
RE: bump/thump when downshifting
You will probably have to go to the dealer. There is a TSB for that concern, involves replacing the transmission front pump and reprogramming the trans module due to a machining defect in the pump that allows the torque converter to drainback overnight. When the vehicle is restarted, the TCM detects a loss of prime because the pressure switches haven't closed when expected due to the refilling of the torque converter and is steps up the underdrive clutch value and you get the bump when it downshifts.
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