I have a 2001 hyundai elantra with automatic transmission. The transmission drops gears with no warning, gets stuck in lower gears....I have had the input and output sensors replaced....things go OK for a while, then the check engine light comes back on and the transmission starts doing weird stuff again. I have been told by our transmission guy that the problem seems to be with the connectors that connect the wires to the sensors, but that these parts cannot be purchased without buying the entire harness kit. any suggestions????

Automatic transmission :Genuine Diamond automatic transmission fluid SP-11M.

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For Manual transmission :SAE 75W/90 gear oil

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To replace the fluid.There are no special requirements here. Drop the pan being careful not to damage the pan gasket with a container to catch the old fluid underneath it, replace the filter, replace the pan and then add about 4 quarts (via the dipstick hole) of the required Hyundai SP-III fluid you can get at the dealer. Double check the level with the engine warm and in park position. Be aware that your transmission uses a specific formulation of transmission fluid, available at the dealer. It is a bit more expensive than off the shelf fluid like Dextron, but you are only changing it every 30K, so the cost over time is minimal. -----------
this should help.thanks.Helpmech