A hybrid powertrain has a transmission including a motor and a sensor for
sensing rotation of the transmission output member. Motor speed signals
are available from the motor controller. Speed signals representative of
output speed are calculated from both the speed sensor and the motor
speed in conjunction with known speed relationships between the motor and
the output. A variety of in-range and dropped signal diagnostics is
performed for the sensors and are used in the development of a set of
software switches for selecting which of the speed sources is used as the
output speed.