Air Pressure Tests

DESCRIPTION
A NO DRIVE condition can exist, even with correct transmission 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 malfunction. Follow the procedure to determine the location of the inoperative clutch or band by introducing air pressure into the various test plate passages.

NOTE:
- Use only dried, regulated (276 kPa [40 psi] maximum) air pressure with Rubber-Tipped Air Gun D93L-7000-A or equivalent. Apply air to the appropriate passage(s). A dull thud should be heard when the clutch or band applies. There should be no hissing sound when the clutch or band is fully applied.
- Cover the vent hole in the test plate with a clean, lint-free shop towel to prevent spray when the air is applied. Plugging the vent hole during testing will result in inaccurate results.

PREPARATION
1. Drain transmission fluid and remove the transmission fluid pan.
2. Remove the main control and gasket.

Transmission Test Plate (Part 1 Of 2):

Transmission Test Plate (Part 2 Of 2):

3. Install AOD-E Transmission Test Plate T92P-7006-A and Replacement Gasket T92P-7006-A1. Tighten bolts to 10-12 Nm (39-106 inch lbs.).
4. A dull thud may be heard or movement felt when the clutch is applied or released. If clutch seals or check balls are leaking a hissing sound may be heard.

NOTE: Do not apply air to the test plate vent hole. Apply air to the appropriate clutch port. Refer to Transmission Test Plate Illustration.

REVERSE CLUTCH
A dull thud can be heard when the reverse clutch piston applies. In addition, movement of the reverse clutch drum may also be detected.

FORWARD CLUTCH CYLINDER
A dull thud can be heard or movement of the clutch piston can be felt on the case as the clutch piston is applied.

INTERMEDIATE CLUTCH CYLINDER
A dull thud can be heard or felt when the intermediate clutch piston applies.

DIRECT CLUTCH CYLINDER
A dull thud should be heard or felt on the driveshaft if the clutch is operating.

OVERDRIVE SERVO
Operation of the band is indicated by the tightening of the band around the reverse clutch drum. The O/D servo will return to the release position as a result of force from the overdrive servo piston return spring. Also, when the servo returns to the release position, a thud can be felt on the O/D servo retaining ring. The band will then relax.

LOW-REVERSE SERVO
A dull thud can be heard when the low-reverse band tightens around the planetary assembly drum surface. Also, movement of the ring gear can be detected.

2-3 ACCUMULATOR
The accumulator piston should unseat. This can be detected by inserting a metal rod into the 2-3 piston hole. When the accumulator piston unseats, the rod will move. Also, a thud can be heard when the accumulator piston applies.

AIR PRESSURE TEST RESULTS
- If the servos do not operate, disassemble, clean and inspect them to locate the source of the concern.
- If air pressure applied to the clutch passages fails to operate a clutch, or operates clutches simultaneously, inspect the fluid passages in the case.
- If air pressure applied to the accumulator fails to operate an accumulator, remove and inspect case passages and piston.