Possible causes of vibration when turning on the automatic transmission in a Subaru:
1. Torque converter malfunction:
* Worn friction linings
*Transmission fluid level too low
* Clogged automatic transmission filter
2. Worn spline joints:
* In the shaft connecting the engine to the automatic transmission
* In the cardan shaft
3. Malfunctions of engine or automatic transmission mounts:
* Worn or torn supports
* Incorrect installation of supports
4. Problems with electronics:
*Speed sensor malfunction
* Malfunction of the electronic control unit (ECU) of the automatic transmission
5. Mechanical damage:
* Damaged gears or bearings in the automatic transmission
* Deformed automatic transmission oil pan
Diagnostics and repair:
To diagnose the exact cause of vibration, you must perform the following steps:
* Check the transmission fluid level and filter condition.
* Inspect the shaft splines for wear or damage.
* Check the condition of the engine and automatic transmission mounts.
* Connect a diagnostic scanner to identify faults in the electronics.
* In some cases, it may be necessary to remove and disassemble the automatic transmission for further diagnosis.
Depending on the cause of the vibration, repairs may include replacing faulty components, installing new mounts, or repairing the electronic system.