Possible causes of vibration when engaging a gear in a Toyota Corolla automatic transmission:
1. Problems with the torque converter:
* Worn torque converter lockup
*Low or contaminated transmission fluid
2. Transmission problems:
* Worn gears, bearings or synchronizers
* Faulty gearbox housing
3. Problems with the driveshaft:
* Unbalanced or damaged driveshaft
* Faulty driveshaft bearings
4. Problems with differential:
* Wear of differential gears
* Faulty differential bearings
5. Clutch problems (on some Corolla models):
* Worn friction linings
*Dirty or old clutch fluid
6. Other possible reasons:
* Worn engine or transmission mounts
* Faulty transmission position sensor
* Incorrect transmission alignment
Diagnostics and repair:
To diagnose the exact cause of vibration, you must perform the following steps:
* Visual inspection of the transmission and driveshaft
* Checking the level and condition of the transmission fluid
* Scan diagnostic error code (if available)
* Checking the operation of automatic transmission solenoids
* Testing the car on the go
Repairs depend on the cause of the vibration and may include:
* Replacing the torque converter
* Gearbox repair or replacement
* Balancing or replacing the driveshaft
* Differential replacement
* Replacing the clutch
* Installation of new engine or transmission mounts