Air Pressure Tests
AIR PRESSURE TESTNOTE: A no drive condition could occur, even with correct transaxle fluid pressure, because of inoperative clutches or bands. An erratic shift can be located through a series of checks by substituting air pressure for fluid pressure to determine the location of the problem.
1. Drain transaxle fluid and remove oil pan.
2. Remove main control cover, then the oil pump, and main control assembly.
Air Pressure Test Plate:
3. Install air pressure test plate with main control assembly to chain cover gasket as shown in the Air Pressure Test Plate image.
4. Inoperative clutches or bands can be located by applying air pressure into the various test passages. Refer to the following test procedures.
Forward Clutch
1. Apply air pressure to forward clutch test port. A dull thud should be heard or movement of piston felt when clutch piston applied. If clutch seals are leaking, a hissing sound will be heard.
2. If air pressure applied to the clutch passages fails to operate a clutch, or operates clutches simultaneously, remove plate, and with air pressure, check fluid passages in the chain cover, driven sprocket support, and clutches to detect blockage.
Direct Clutch
1. Apply air pressure to direct clutch test port. A dull thud should be heard or movement of piston felt on case as clutch piston is applied. If clutch seals are leaking, a hissing should be heard.
2. If air pressure applied to the clutch passages fails to operate a clutch, or operates clutches simultaneously, remove plate, and with air pressure, check fluid passages in the chain cover, driven sprocket support, and clutches to detect blockage.
Intermediate Clutch
1. Apply air pressure to intermediate clutch test port. A dull thud should be heard or movement of piston can be felt on case as clutch piston is applied. If clutch seals are leaking, a hissing should be heard.
2. If air pressure applied to the clutch passages fails to operate a clutch, or operates clutches simultaneously, remove plate, and with air pressure, check fluid passages in the chain cover, driven sprocket support, and clutches to detect blockage.
Low-Intermediate Servo
1. Apply air pressure at low-intermediate servo feed test port. The low-intermediate band should tighten around sun gear of rear planetary gear set. Because of the cushioning effect of the servo release spring, application of band may not be heard or felt.
2. The servo should hold air pressure without leakage and a dull thud should be heard when air pressure is removed, allowing servo piston to return to release position.
3. Apply air pressure to low-intermediate servo release port while continuing to pressurize the apply port. Servo piston should return to the release position. The band should loosen and a dull thud should be heard.
4. Release the feed test port. The release test port should hold pressure without leakage. Any leakage or failure of piston movement requires servo service.
5. If servo does not operate satisfactorily, disassemble, clean, and inspect them to locate the source of trouble.
Lube And Rear Lube
1. Apply air pressure to lube and rear lube test ports. These passages can only be checked for blockage.
2. If either passage holds air pressure, remove service tool plate and check for blockage or damage.
1-2, 3-4, And N-D Accumulators
1. Apply air pressure to each accumulator feed port. Accumulator should apply.
NOTE: Because of the cushioning effect of the accumulator release spring, application of the accumulator may not be heard or felt.
2. The accumulator should hold air pressure without leakage and a dull thud should be heard when air pressure is removed, allowing accumulator to return to release position.
3. If air pressure applied to the accumulator passages fail to operate the accumulator, remove and check fluid passages with air pressure in the chain cover to detect blockage.