Possible causes of vibration when turning on the automatic transmission speed:
Engine problems:
* Faulty spark plugs or ignition coils
*Dirty or clogged fuel injectors
* Cylinder compression problems
Transmission problems:
* Worn or faulty engine and transmission mounts
* Transmission fluid problems (low level, dirty or incorrect fluid)
* Faulty torque converter
* Worn or faulty gears or synchronizers
Problems with the driveshaft:
* Unbalanced or damaged driveshaft
* Faulty driveshaft outboard bearings
Other possible reasons:
* Faulty sensors or faulty wiring
* Faulty exhaust system (vibrations from the engine can be transmitted through the exhaust system)
* Problems with tires or wheels (imbalance, incorrect tire pressure)
Troubleshooting Suggestions:
* Check Engine: Inspect spark plugs, ignition coils and fuel injectors. Measure the cylinder compression.
* Check the transmission: Check the level and condition of the transmission fluid. Inspect the engine and transmission mounts for wear or damage. Diagnose problems with the torque converter, gears and synchronizers.
* Check driveshaft: Check driveshaft for imbalance or damage. Replace outboard bearings if necessary.
* Eliminate other possible causes: Check sensors and wiring for faults. Correct problems with the exhaust system. Balance the wheels and adjust the tire pressure.
Tip: If vibration occurs, you should immediately contact a car service to diagnose and repair the problem to prevent it from worsening and costly repairs in the future.