6R75 - Automatic Transmission
Air Pressure TestAir Pressure Test:
A no-drive condition can exist, even with correct transmission fluid pressure, because of inoperative clutches or bands. Refer to the Clutch Application Chart to determine the appropriate elements. Clutch concern can be located through a series of checks by substituting air pressure for fluid pressure to determine the location of the concern.
Example: When the transmission range selector lever is in a forward gear range (D, 3, 2, 1), a no-drive condition may be caused by an inoperative forward clutch.
1. Drain the transmission fluid. Remove the transmission fluid pan.
2. Remove the filter and seal assembly and the mechatronics unit.
3. The inoperative clutches can be located by applying air pressure into the appropriate clutch port.
4. Apply air pressure to the appropriate clutch port. dull thud may be heard or movement felt when a clutch piston is applied. If the clutch seals or check ball are leaking, a hissing may be heard.
5. If the clutches fail to operate during the air check:
^ the piston seals are not seated, damaged or not installed correctly.
^ plugged feed holes for clutch apply in the case and/or clutch cylinder.
^ damaged piston and/or clutch cylinder.
6. Service as required and recheck.