Correct diagnosis of automatic transmission
1. Checking the level and condition of the transmission fluid (ATF)
* Check the ATF level with the engine running in park or neutral.
* Look for signs of burns, darkening or a burning smell, which may indicate transmission problems.
2. Scan Trouble Codes (DTC)
*Connect the OBD-II scanner to the vehicle.
* Read and record any automatic transmission related DTCs.
*Refer to technical manual for interpretation of codes.
3. Checking the pressure in the automatic transmission
* Use a pressure gauge to measure pressure at various points in the automatic transmission.
*Compare results with factory specifications.
*Low or high pressure may indicate problems with the pump, valves or solenoids.
4. Test for the presence of a slip
* Place the car in park and start the engine.
* Apply the handbrake and shift into gear (D or R).
*Press the gas pedal and see if the car moves.
* Clumping (delay in transmission actuation) may indicate problems with clutches, clutches or solenoids.
5. Load shift test
* Accelerate the car to a speed of about 50 km/h on a flat road.
*Press the gas pedal half to three-quarters of the way and watch the transmission react.
*Rough shifting or slipping may indicate problems with the shift valves or control module.
6. Noise and vibration test
* Listen carefully for any unusual noises or vibrations from the automatic transmission, especially when changing gears or accelerating.
* Noises may indicate worn bearings, damaged gears, or torque converter problems.
7. Checking the condition of connectors and wiring harnesses
* Visually inspect the connectors and wiring harnesses associated with the automatic transmission.
* Look for signs of corrosion, damage or loose connections.
* Electrical problems can cause the automatic transmission to malfunction.
8. Leak test
* Inspect the transmission housing and adjacent components for ATF leaks.
*Leaks may indicate worn seals, cracks, or holes in the housing.
After diagnosis:
* Interpret results and determine possible causes of problems.
* Document your findings and recommendations for repairs.
* If necessary, consult an automatic transmission repair specialist for further diagnosis and repair.