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NO.14 ENGINE FLARES UP OR SLIPS WHEN UPSHIFTING OR DOWNSHIFTING [FN4A-EL]

id0503a1801900

14 | Engine flares up or slips when upshifting or downshifting
DESCRIPTION | • When accelerator pedal is depressed when starting from a stop, engine speed increases but vehicle speed increases slowly. • When accelerator pedal is depressed while driving, engine speed increases but vehicle does not.
POSSIBLE CAUSE | • There is clutch slip because clutch is stuck or line pressure is low. 1. Clutch stuck, slippage (forward clutch, 3-4 clutch, 2-4 brake band, one-way clutch) • Line pressure low • Shift solenoid D malfunction • Shift solenoid E malfunction • Shift solenoid A malfunction • Shift solenoid B malfunction • Shift solenoid C malfunction • Pressure control solenoid malfunction • Body GND malfunction • Accelerator cable misadjustment • Control valve body malfunction 2. Signal malfunction • Vehicle speed sensor malfunction • Sensor GND malfunction • TP sensor malfunction or mis-adjustment • Input/turbine speed sensor malfunction 3. Poor operation of mechanical pressure • Selector lever position disparity • TR switch position disparity Note • Before following troubleshooting steps, make sure that Automatic Transaxle On-Board Diagnostic and Automatic Transaxle Basic Inspection are conducted.

Diagnostic procedure

STEP | INSPECTION | ACTION
--- | --- | ---
1 | • Is shift point normal? | Yes | Go to next step.
No | Go to No.9 "ABNORMAL SHIFTING"
2 | • Check the value at the following PID using the WDS or equivalent. (See PCM INSPECTION [WITHOUT WU-TWC].) (See PCM INSPECTION [WITH WU-TWC].) - TP • Is PID value normal? | Yes | Go to next step.
No | Repair or replace any defective parts.
3 | • Disconnect PCM. • Is resistance between ground terminal at PCM connector and body ground less than 5.0 ohms? | Yes | Go to next step.
No | Repair open ground circuit. Reconnect PCM.
4 | • Check LPS PID value. (See PCM INSPECTION [WITHOUT WU-TWC].) (See PCM INSPECTION [WITH WU-TWC].) • Is LPS PID value normal? | Yes | Overhaul control valve body and repair or replace any defective parts. (See ATX workshop manual (FN4A-EL) [1623-10-98E].) If problem remains, overhaul transaxle and repair or replace any defective parts. (See ATX workshop manual (FN4A-EL) [1623-10-98E].)
No | Repair or replace any defective parts.
5 | • Verify test results. - If normal, return to diagnostic index to service any additional symptoms. - If malfunction remains, inspect related Service Information and perform repair or diagnosis. • If vehicle repaired, troubleshooting completed. • If vehicle not repaired or additional diagnostic information not available, replace PCM.