Diagnostics of automatic transmission faults
1. Inspection
* Visual inspection for leaks, cracks or damage.
* Checking the level and condition of transmission fluid (ATF).
2. Test drive
* Check gear shifting at different speeds and loads.
* Pay attention to sliding, vibration, jolting or other unusual sounds.
3. Reading fault codes
*Connect the OBD-II diagnostic scanner to the vehicle.
* Read and decipher trouble codes (DTCs).
4. Checking solenoids
* Using a diagnostic scanner, check the condition of the automatic transmission solenoids (valves).
* Faulty solenoids can cause shifting problems.
5. Checking the sensors
* Speed, gear position and pressure sensors transmit information to the automatic transmission controller.
* Faulty sensors may result in incorrect gear shifting.
6. Hydraulic test
* Check ATF pressure and flow rate in various automatic transmission modes.
*Low or high pressure may indicate problems with the pump, valves, or other hydraulic system components.
7. Mechanical inspection
* Remove the automatic transmission from the car and disassemble it.
* Check the condition of friction discs, steel discs, bearings and other mechanical components.
* Wear or damage may cause automatic transmission problems.
Common automatic transmission malfunctions and their possible causes:
* Slip – worn friction discs, faulty solenoids, low ATF pressure.
* Shocks – faulty solenoids, problems with hydraulic pressure, wear of friction discs.
* Vibration – faulty bearings, driveshaft imbalance, torque converter problems.
* Gear shift delay – faulty speed sensors, problems with solenoids, low ATF pressure.
* Lack of gear shifting – faulty automatic transmission controller, blown fuse, mechanical damage.
Note: Automatic transmission diagnosis and repair should be performed by a certified mechanic as it is a complex and technical procedure.