Internal diagnostics
*Checking the transmission fluid level and condition: Check the fluid level with the dipstick and evaluate its color, smell and cleanliness.
*Checking Trouble Codes: Connect a diagnostic scan tool to the vehicle to check for transmission related trouble codes.
*Checking Transmission Pressure: Use a special pressure gauge to check the pressure at various points in the transmission.
External diagnostics
* Visual Inspection: Inspect the transmission for leaks, damage or signs of wear. Check the condition of the fasteners and gaskets.
* Listening for Noises: Take it for a test drive and listen for unusual noises such as humming, buzzing or clicking. These noises may indicate problems with the transmission.
*Checking gear shifting: Check for smooth gear shifting in all modes. Pay attention to any delays, slippages or bumps.
Road test
* Acceleration: Check the car’s acceleration from a standstill and at different speeds. Lack of power or transmission slipping may indicate problems.
* Engine braking: Check the effectiveness of engine braking while coasting. Poor engine braking may indicate worn bands or clutches.
* Hill Acceleration: Check how the transmission handles the load when driving uphill. Slipping or failure to maintain the desired gear may indicate problems with the torque converter or line pressure valve.
Other diagnostic tests
*Checking Shaft Speed: Use a scan tool or tachometer to check the rotation speed of the transmission input and output shafts. A speed discrepancy may indicate problems with the planetary gear or differential.
*Torque Converter Check: Check torque converter locking and slippage. A faulty torque converter can lead to slippage, overheating and shifting problems.