Systems and methods for operating a transmission of a hybrid powertrain that includes a motor/generator are described. The systems and methods may classify transmission degradation in response to an estimated transmission input shaft speed that is determined from transmission output shaft speed. In one example, transmission degradation may be correctable transmission degradation, partial transmission degradation, and continuous transmission degradation.

The invention relates to a method for changing gear stages in a transmission having a hydrostatic transmission and a downstream manual transmission, and a corresponding transmission arrangement. First, a desire to shift is detected within the manual transmission to change the gear stages. The hydrostatic transmission and the downstream manual transmission are activated to change the gear stage of the downstream transmission. Whether the gear stage to be engaged through a gear stage change was successfully engaged is detected by a detection device, which is connected to an electronic control unit of the transmission arrangement. If the engagement of the gear stage to be engaged is not successful, the original gear stage is reengaged. After the engagement of the original gear stage, the downstream transmission is again activated such that the gear stage to be engaged is engaged.

A hybrid electric vehicle (HEV) includes an internal combustion engine, an electric traction motor, a motor/generator configured to start the internal combustion engine, a transmission, and a powertrain control system including a controller having one or more processors. The controller is programmed to monitor the transmission for a gear shift while the HEV operates in an EV mode where the electric traction motor provides propulsion for the HEV, detect a driver torque request during the gear shift, and turn the internal combustion engine on to provide torque to the HEV during the gear shift.