Possible reasons:
* Low or contaminated transmission fluid (ATF): Transmission fluid lubricates and cools automatic transmission components. Low or contaminated fluid levels can result in insufficient oil pressure, causing slipping and jerking when shifting.
* Sensor or wiring problems: Sensors such as the speed sensor or throttle position sensor provide vital information for the automatic transmission to operate properly. A faulty sensor or wiring problem may cause the transmission to shift incorrectly.
* Faulty solenoids: Solenoids regulate the flow of ATF into the automatic transmission. Faulty solenoids can direct the wrong amount of fluid to a particular clutch pack, resulting in jerking or slipping.
* Worn or damaged clutches: Clutches provide the clutch to change gears. Worn or damaged clutches can cause gears to slip or engage harshly.
* Faulty torque converter: The torque converter connects the engine to the automatic transmission. A faulty torque converter can cause torque fluctuations that appear as jerks.
* Problems with mechanical components: Less commonly, problems may be related to mechanical components such as gears, shafts, or bearings. Wear or damage to these components may cause noise, vibration, or slippage.
Diagnostics and repair:
* Check the ATF level and condition and replace it if necessary.
* Run computer diagnostics to identify trouble codes related to the automatic transmission.
* Check sensors and wiring for functionality.
* Inspect the solenoids and clutches during a major overhaul of the automatic transmission.
* Repair or replace the faulty torque converter.
* If necessary, repair any problems with mechanical components.
Important: At the first sign of shifting shock, take your vehicle to a qualified mechanic for diagnosis and repair. Correcting the problem in a timely manner will help prevent further damage to the automatic transmission and costly repairs.