Transmission Fluid Level and Condition
Transmission fluid level and condition are monitored and serviced at regular intervals. Always check the fluid levels before test driving or beginning diagnosis. This is typically done with the engine running and the transmission at operating temperature. The fluid temperature can be verified with a scan tool by viewing the TFT transmission fluid temperature sensor data. This is likely somewhere between 175° F and 200° F. Check with manufacturer’s specifications.
If the level is low, the fluid will become aerated and foamy. This condition is especially noticeable while cornering or going up and down hills. This is because air is being drawn up into the oil pump inlet. Because air is compressible, aerated fluid results in low fluid pressures and delayed gear engagement, buzzing and malfunctioning valves, and slippage between shifts.
If the level is low check for exterior leaks.
Check: Cooler and lines - Axle Seals- Torque converter shell - Oil pump seal - Switches - Vehicle Speed Sensor - Extension housing seals - Case porosity
Always check the condition of the fluid while checking its level. Use a piece of paper towel or a lint free cloth. Automatic transmission fluid should be red. Only in a few transmissions is the dye left out. If the fluid has been overheated, it will appear dark brown or black. Overheated fluid results in oxidation. This can be evident when the dipstick is tarnished brown. Pieces of black particles in the fluid indicate slipping friction materials. Wearing metal components result in silvery metal pieces in the fluid. If the fluid’s pink and milky, it’s become contaminated with coolant in the transmission fluid cooler inside the radiator.