What are the reasons for an automatic transmission not shifting gears?
3 Answers
Automatic transmission not shifting gears can be caused by: 1. Gear lock; 2. The car was not fully braked when parking, and the P gear was directly engaged, resulting in the gear brake being unable to shift. Automatic transmission vehicles can automatically select the appropriate gear for driving based on the speed and traffic conditions. There are 6 gear positions for automatic transmission cars, namely P gear, R gear, N gear, D gear, S gear, and L gear. Precautions for shifting gears in automatic transmission: 1. Do not step on the accelerator pedal when shifting gears; 2. Do not immediately press the accelerator pedal hard after engaging the gear; 3. The vehicle can only be started in P or N gear; 4. The gear lever must be removed from P gear by stepping on the brake; 5. Do not shift into N gear while driving; 6. Do not push into P gear while the car is moving; 7. When changing the direction of travel, switching between D gear and R gear must be done after the vehicle has come to a complete stop.
I've been driving automatic transmission cars for over twenty years and have encountered gear shifting issues quite a few times. The most common cause is internal transmission problems, such as stuck gears or insufficient fluid levels, leading to system failure. The electronic control components may also malfunction, like broken sensors or computer faults, making the gear lever difficult to move. Sometimes it's just a simple mistake, like not pressing the brake pedal firmly enough—modern cars all have this safety lock. I remember once on the highway when I couldn't shift gears, it was due to dirty transmission fluid causing the issue, and it had to be towed for repairs. Daily driving requires paying attention to unusual sounds, regular fluid checks, and system maintenance. If shifting feels rough, don't force it—take it to a professional shop promptly to avoid damaging the car or causing accidents.
I've been repairing automatic transmission vehicles for over a decade, and while gear engagement failure is common, it's diagnosable. First is the shift lock issue - if the brake pedal isn't fully depressed, the safety mechanism will lock the gear lever. Second is transmission component failure, where valve body blockage or clutch plate wear prevents gear engagement. Third involves electronic system malfunctions, like low battery voltage affecting the control unit or faulty sensor signals. Once a frantic customer reported gear engagement failure, and testing revealed deteriorated transmission fluid needing replacement. Routine maintenance suggests checking fluid levels every 30,000 km - using a diagnostic scanner to read trouble codes is most accurate when issues arise. Non-professionals should avoid disassembly and seek reputable repair services promptly.
