Toyota automatic transmission diagnostics
Visual inspection
* Check the level and condition of the transmission fluid (ATF). It should be pink or red in color and without a burning smell.
* Inspect the transmission pan for leaks or damage.
Scan Trouble Codes (DTC)
* Connect the OBD scanner or Toyota Techstream to the vehicle’s diagnostic port.
* Scan for trouble codes and write down any codes found.
* Decipher trouble codes using your service manual or online resources.
Physical tests
* Shear Test: Start the engine and put the transmission in Drive. Accelerate and pay attention to the smoothness and timing of the gear changes.
* Slip test: Accelerate to a speed of about 60 km/h and put the transmission in “Overdrive” mode. Press the accelerator pedal and watch for any jumps in engine speed or slippage.
* Stopping test: Stop the vehicle completely and place the selector in Park mode. Release the brake pedal and notice vibration or noise from the transmission.
Advanced tests
* ATF Analysis: Collect a sample of ATF and send it to a laboratory for analysis. This may reveal wear or contamination.
*Transmission Pressure Sensor: Measure the ATF pressure under various transmission operating conditions to check the serviceability of the pressure sensor.
* Solenoid Check: Check the electrical resistance and operation of the transmission solenoids that control ATF flow.
Possible causes of automatic transmission malfunctions
* Low or dirty ATF level
* Worn clutches or steel discs
* Faulty solenoids
* Problems with the hydraulic control unit
* Electrical faults in the wiring harness or transmission control module (TCM)
Note: Automatic transmission diagnostics must be performed by a qualified mechanic with the appropriate tools and knowledge.