5 Common Causes of Hard Shifting in Automatic Transmissions

Does your vehicle jerk when shifting between gears? Known as hard shifting, it's a common problem in automatic transmissions. Automatic transmissions, of course, change their gears automatically. Sensors will tell your vehicle's transmission when to shift to a higher gear. At it performs this gear change, though, it may jerk. Some of the most common causes of hard shifting in automatic transmissions include the following.

#1) Faulty Sensors

Faulty sensors can cause hard shifting in automatic transmissions. As previously mentioned, automatic transmissions leverage sensors to shift their gears. Sensors work in conjunction with the engine control module (ECM). They send signals to the ECM telling the automatic transmission when to shift its gears. If your vehicle has one or more faulty sensors, it may suffer from hard shifting.

#2) Solenoid Failure

Solenoid failure can lead to hard shifting. Solenoids are devices that control the flow of transmission fluid. While manual transmissions typically don't have them, automatic transmissions have several solenoids. Solenoid failure can manifest in different ways, one of which is hard shifting. If a solenoid has failed in your vehicle, the transmission may jerk as it shifts gears.

#3) Cold Temperatures

You might be surprised to learn that cold temperatures can cause hard shifting in automatic transmissions. Automatic transmissions require fluid to function properly, specifically Automatic Transmission Fluid (ATF). The viscosity of ATF is influenced by the ambient temperature. In cold temperatures, ATF becomes thicker and less viscous. If you believe cold weather is to blame for your vehicle's hard shifting, you may want to switch to a synthetic ATF formula.

#4) Fluid Contamination

Another common cause of hard shifting in automatic transmissions is fluid contamination. Like most automotive fluids, ATF operates in a closed environment. Your vehicle should have an ATF reservoir. When you crank it up, ATF will flow from the reservoir to the automatic transmission. But contaminants can make their way inside of this reservoir. As these contaminants build up, they can interfere with your automatic transmission's operations. You may feel it slip or shift hard due to ATF contamination.

#5) Loss of Vacuum

A loss of vacuum may cause your vehicle to experience hard shifting. Automatic transmissions have vacuum lines. Vacuum lines create pressure that allows ATF to circulate through them. If a vacuum line is punctured, your automatic transmission will lose this vacuum. Regardless, a loss of vacuum can cause hard shifting in automatic transmissions.