A transmission diagnostic system includes a pivotable member and an actuator. The actuator has a notch with a first side, a second side, and an opening between the two sides. The width of the opening is greater than a width of the pivotable member. The pivotable member is retained within the notch, and the actuator is configured to selectively pivot the pivotable member between an engaged position, corresponding to a PARK gear, and a disengaged position, corresponding to a gear other than PARK. The transmission diagnostic system also includes a biasing spring configured to exert a biasing torque on the pivotable member to bias the pivotable member toward the first side of the notch. The transmission diagnostic system further includes a controller configured to generate at least one diagnostic signal in response to the pivotable member not being in contact with the first side of the notch.