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

BME050301030218

14 | Engine flares up or slips when upshifting or downshifting
DESCRIPTION | • When the accelerator pedal is depressed, engine speed increases normally but vehicle speed increases slowly. • When the accelerator pedal is depressed while driving, engine speed increases but the vehicle does not.
POSSIBLE CAUSE | • There is clutch slippage because the 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 mis-adjustment
  • 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 the troubleshooting steps, make sure that the Automatic Transaxle On-Board Diagnostic and Automatic Transaxle Basic Inspection are conducted.

Diagnostic procedure

STEP | INSPECTION | ACTION
--- | --- | ---
1 | Is the shift point normal? | Yes | Go to the next step.
No | Go to No.9 "ABNORMAL SHIFTING".
2 | Inspect the value at the following PCM PID using the WDS or equivalent. (See PCM INSPECTION [L3].) • TP Is the PID value normal? | Yes | Go to the next step.
No | Repair or replace any malfunctioning parts.
3 | Disconnect the PCM connector. Is the resistance between the ground terminal at the PCM connector and the body ground less than 5.0 ohms? | Yes | Go to the next step.
No | Repair the open ground circuit. Reconnect the PCM.
4 | Inspect the LPS PID value using the WDS or equivalent. Is the LPS PID value normal? (See PCM INSPECTION [L3].) | Yes | Overhaul the control valve body and repair or replace any malfunctioning parts. (See ATX workshop manual (FN4A-EL).) If any problem remains, overhaul the transaxle and repair or replace any malfunctioning parts. (See ATX workshop manual (FN4A-EL).)
No | Repair or replace any malfunctioning parts.