Which of the following is a common cause of hard shifting in an automatic transmission?

Low transmission fluid levels are a common cause of hard shifting in an automatic transmission because the transmission relies on hydraulic fluid to operate the various components effectively. Insufficient fluid can lead to inadequate hydraulic pressure, which may result in harsh or erratic shifting as the hydraulic pressure cannot engage the clutches and bands smoothly.

When the fluid level drops too low, it can affect the transmission's ability to shift gears seamlessly, causing increased wear on internal components and possibly leading to further damage. Regular maintenance, including checking fluid levels and changing the fluid as recommended, is crucial in preventing this issue. Other factors, such as high engine temperature or ECU software problems, may also impact transmission performance, but low fluid levels are a direct, mechanical cause of hard shifting.