NO.25 SHIFT CONCERN: HARSH 4–3 SHIFT (AUTOMATIC)[LA4AX-EL (CD4E)]

id0503a2805900

25

Shift concern: harsh 4–3 shift (automatic)

POSSIBLE CAUSE

•  Powertrain control system malfunction

•  Control valve body malfunction

•  Oil pump malfunction

•  2/4 band and servo component malfunction

•  Coasting clutch component malfunction

•  Transaxle case malfunction

25	Shift concern: harsh 4–3 shift (automatic)
POSSIBLE CAUSE	• Powertrain control system malfunction • Control valve body malfunction • Oil pump malfunction • 2/4 band and servo component malfunction • 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 ― Transaxle range (TR) switch ― Vehicle speedometer sensor (VSS) ― Throttle position (TP) sensor ― Transaxle fluid temperature (TFT) sensor ― Mass air flow (MAF) sensor ― Turbine shaft speed (TSS) sensor ― 3-2 timing/coasting clutch solenoid (3-2T/CCS) ― TCC solenoid	Yes	Perform OBD test Perform DTC troubleshooting (See AUTOMATIC TRANSAXLE ON-BOARD DIAGNOSTIC FUNCTION[LA4AX-EL (CD4E)].)
1		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, 3-2 timing/coast clutch valve are stuck, damaged, or misassembled ― Hydraulic passages are damaged ― Separator plates are damaged or blocked	Yes	Service if necessary
2		No	Go to the next step
3	Oil pump • Do any of the following malfunctions exist? ― Bolts are not tightened to the specification ― Porosity/cross leaks, seal rings are damaged, missing or ball plug is leaking ― Gasket damaged ― Pump support seal rings #2, 3, 4, and #5 (coast and direct circuits) are damaged	Yes	Service if necessary
3		No	Go to the next step
4	2/4 band and servo component • Do either of the following malfunctions exist? ― Servo rod is bent or damaged ― Servo return spring is broken	Yes	Service if necessary
4		No	Go to the next step
5	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
5		No	Go to the next step
6	Transaxle Case • Does the following malfunction exist? ― Porosity/cross leaks in servo apply, servo release, direct clutch, coasting clutch circuits	Yes	Service if necessary
6		No	The malfunction is not in the automatic transaxle Go to the engine symptom troubleshooting (See ENGINE SYMPTOM TROUBLESHOOTING[AJ (3.0L Duratec)].)
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 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.