NO.19 SHIFT CONCERN: SOFT/SLIPPING 4-3 SHIFT (AUTOMATIC) [LA4AX-EL (CD4E)]


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19

Shift concern: soft/slipping 4-3 shift (automatic)

POSSIBLE CAUSE

• Powertrain control system malfunction
• Control valve body malfunction
2/4 band and servo component malfunction
• Direct clutch component malfunction
• Forward/coasting 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
- Vehicle speedometer sensor (VSS)
- Mass air flow (MAF) sensor
- Throttle position (TP) 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
- Servo release shutter valve, main regulator valve are stuck, damaged, or misassembled
- Hydraulic passages are damaged
- Pressure tap plate/gasket leaks, or damaged
- Separator plates are damaged or 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 damaged, worn, or misassembled
- Servo return spring is broken
- Servo rod is damaged
- Piston seal is damaged
Yes
Service if necessary
No
Go to the next step
4
Direct clutch component
• Do any of the following malfunctions exist?
- Seals are damaged or missing
- Piston is 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
Forward/coasting clutch component
• Do any of the following malfunctions exist?
- Seals are damaged or missing
- Piston is damaged
- Friction elements are worn or damaged
- The ball is not functioning
- Forward clutch piston and return spring are damaged
Yes
Service if necessary
No
Go to the next step
6
Transaxle case
• Do any of the following malfunctions exists?
- Porosity/cross leaks in servo apply, servo release, direct clutch circuits
Yes
Service if necessary
No
The malfunction is not in the automatic transaxle
Go to the engine symptom troubleshooting
7
• 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.