Code No. P264B: Valve Lift Sensor Poor Sensitivity


OPERATION



  • A power voltage of 5 V is applied to the valve lift sensor connector terminal from the engine-ECU connector terminal VLS5.
  • The power voltage is earthed to the engine-ECU connector terminal VLSE from the valve lift sensor connector terminal.
  • The sensor signal is inputted to the engine-ECU connector terminal VLS from the valve lift sensor output terminal.

FUNCTION



  • The valve lift sensor converts valve lift amount to voltage signal, and then sends it to the engine-ECU.
  • The engine-ECU uses this signal to control the valve lift mount.

TROUBLE JUDGMENT


Check Conditions
  • After 2 seconds since the ignition switch is turned ON or since the completion of engine start.
  • The valve lift sensor has been initialised completely.
  • The valve lift ECU has determined that the system communicates with the engine-ECU via VLC-CAN normally.
  • The following diagnosis codes have not been set.

  1. P264C: Valve lift sensor circuit low input
  2. P264D: Valve lift sensor circuit high input
  3. P265B: Malfunction of valve lift control motor-integrated Hall sensor
Judgement Criteria
  • The difference between the virtual control angle and the actual control angle, which is calculated from the valve lift sensor output signal, exceeds the a predetermined value position.


  • The minimum valve lift position is abnormal.


  • The maximum valve lift position is abnormal.
note Virtual control angle: The value which the valve lift ECU has calculated in accordance with the valve lift sensor output signal (the engine-ECU communicates via VLC-CAN).
note Actual control angle: The value calculated from the valve lift sensor output

FAIL-SAFE AND BACKUP FUNCTION



  • The valve lift is fixed to maximum. Otherwise, deenergises the motor.
  • V.V.T. phase angle is set to most retarded position.

PROBABLE CAUSES



  • Harness damage in accelerator pedal position sensor circuit or loose connector contact
  • The valve lift sensor improperly installed
  • Failed valve lift sensor
  • Defective variable valve lift system
  • Failed valve lift ECU
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check whether the valve lift sensor is installed properly.

Q. Is the check result normal?
Go to Step 2.
Repair

STEP 2. Check harness between engine-ECU connector terminal VLS5 and valve lift sensor connector terminal.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 3.
Repair or replace the connector, or repair the damaged harness wire.

STEP 3. Check harness between engine-ECU connector terminal VLSE and valve lift sensor connector terminal.

  • Check earthing line for open circuit and damage.

Q. Is the check result normal?
Go to Step 4.
Repair or replace the connector, or repair the damaged harness wire.

STEP 4. Check harness between engine-ECU connector terminal VLS and valve lift sensor connector terminal.

  • Check output line for damage.

Q. Is the check result normal?
Go to Step 5.
Repair or replace the connector, or repair the damaged harness wire.

STEP 5. Variable valve lift mechanism check

  • Variable valve lift mechanism check (Refer to GROUP 11C - On-vehicle Service - Variable valve lift mechanism check ).

Q. Is the check result normal?
Go to Step 6.
Repair

STEP 6. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

Q. Is diagnosis code set?
Replace the engine-ECU.
Check end.