The Transmission Fluid Pressure is too low.

Preform the Line Pressure Check .

The Torque Converter is defective.

Replace the Torque Converter.

Loss of fluid in the circuit between the Accumulator and the Brake Band

1. Search for the leaking part.
2. Replace the leaking part.

The Brake band is incorrectly adjusted.

Adjust the Brake Band.

The Free Wheel (Planetary Set or 4th Gear Unit) is defective.

Replace the Free Wheel (Planetary Set or 4th Gear Unit).

There is fluid loss in the Converter Clutch Fluid Circuit.

1. Search for the leaking part.
2. Replace the leaking part.