NO.18 SHIFT CONCERN: SOFT/SLIPPING 3-4 SHIFT [LA4AX-EL (CD4E)]


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18

Shift concern: soft/slipping 3-4 shift

POSSIBLE CAUSE

• Powertrain control system malfunction
• Control valve body malfunction
2/4 band and servo component malfunction
• Direct clutch component malfunction
• Transaxle case malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION

1
Powertrain control system
• Are there any malfunctions with the following?
- Electrical input/output
- Vehicle wiring harness
- PCM
- Electrical pressure control (EPC) solenoid
- Transaxle fluid temperature (TFT) sensor
Yes
Perform OBD test
Perform DTC troubleshooting
No
Go to the next step
2
Control valve body
• Do any of the following malfunctions exist?
- Bolts are not tightened to the specification
- Gasket leaks
- Line modulator valve, 2/4 accumulator valve plug and seal (also soft 1-2 shift), are stuck, damaged, or misassembled
- Pressure tap plate/gasket leaks
- Hydraulic passages are damaged
- Separator plates are damaged, or the orifice is blocked
Yes
Service if necessary
No
Go to the next step
3
2/4 band and servo component
• Do any of the following malfunctions exist?
- 2/4 Band and/or reverse clutch drum component are worn, damaged, or misassembled
- Piston seals or piston bore is damaged or missing
- Servo cover or seal is damaged
- Servo rod or rod bore is damaged
- Springs are damaged
Yes
Service if necessary
No
Go to the next step
4
Direct clutch component
(There may also be third gear slipping)
• Do any of the following malfunctions exist?
- Seals are damaged or missing
- Pistons are damaged
- Inspect the check ball for damage, loss, or leakage
- Return spring is damaged
- Friction elements are damaged
Yes
Service if necessary
No
Go to the next step
5
Transaxle case
• Do any of the following malfunctions exist?
- Band anchor is damaged
- Leakage in the servo apply and servo release
Yes
Service if necessary
No
The malfunction is not in the automatic transaxle
Go to the engine symptom troubleshooting
6
• Verify the test results.
- If normal, return to the diagnostic index to service any additional symptoms.
- If the malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis.
• If the vehicle is repaired, troubleshooting is completed.
• If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM.