Air Pressure Test
A "No Drive" condition can exist, even with correct transmission fluid pressure, due to inoperative clutches or bands. Inoperative units can be located through a series of checks by substituting air pressure for fluid pressure to determine location of malfunction.
To check unit, drain transmission fluid. Remove oil pan, gasket and control valve body. See VALVE BODY removal procedure under ON-VEHICLE SERVICE. Install Transmission Test Plate (49 UN01 021 ). Using shop air (40 psi maximum), apply air to indicated points. See Fig 1 .
A dull thud can be heard or movement felt when clutch or band is applied. If clutch seals or check balls are leaking a hissing sound may be heard. If air pressure applied to a clutch passage fails to operate clutch or operates clutches simultaneously, check fluid passages in case and oil pump. Use air pressure to detect obstructions.