Welcome to 2CarPros,
From your description I would start by checking the fluid level. Low fluid could cause this. If the fluid is clean and red with no grit and the level is okay then the next step would be to scan the transmission control module to see if there are any codes stored that could provide a direction of repair. If there are no codes then do a pressure test on the transmission to see if the internal pump is good. If the fluid and pressures check okay the transmission will likely need to be removed and checked for internal parts failure.
Tuesday, January 8th, 2019 AT 8:14 AM