Posted in MMC L200

P0088 – Common Rail High Pressure Malfunction MMC L200 IV

 Posted by  Posted on September 28, 2020

OPERATION

  • 5 V power is supplied from the engine-ECU (terminal No. 70) to the rail pressure sensor (terminal No. 1).
  • The rail pressure sensor (terminal No. 3) is earthed to the engine-ECU (terminal No. 88).
  • Sensor signals are input from the rail pressure sensor (terminal No. 2) to the engine-ECU (terminal No. 64).

    • FUNCTION

  • The engine-ECU monitors the signals input from the rail pressure sensor.
  • Based on The input signals, the engine-ECU checks whether the fuel pressure in the common rail exceeds the maximum withstand pressure of the system.

    • TROUBLE JUDGMENT

  • Rail pressure sensor is normal
  • Battery positive voltage is 8 – 16 V
  • The rail pressure exceeds the threshold value of an abnormal high pressure for 3 seconds (continuous or accumulated).

    • PROBABLE CAUSES

  • Failed suction control valve
  • Failed rail pressure sensor
  • Failed engine-ECU

    • DIAGNOSIS PROCEDURE

    STEP 1. M.U.T.-III diagnosis code

    Q. Is any other diagnosis code than P0088 set?

    STEP 2. Check suction control valve itself

    Q. Is the check result normal?

    STEP 3. Connector check: C-105 engine-ECU connector and A-47 suction control valve connector.

    Q. Are the check results normal?

    STEP 4. Check harness between C-105 (terminal No. 131) engine-ECU connector and A-47 (terminal No. 1) suction control valve connector.

  • Check output line for open/short circuit and damage.

    • Q. Is the check result normal?

    STEP 5. Check harness between C-105 (terminal No. 146) engine-ECU connector and A-47 (terminal No. 2) suction control valve connector.

  • Check output line for open/short circuit and damage.

    • Q. Is the check result normal?

    STEP 6. Perform output wave pattern measurement at A-47 suction control valve (Using an oscilloscope).

  • Engine: Idling
  • Connect the oscilloscope special patterns pickup to engine-ECU terminal No. 146 and earth.

    • Q. Is the check result normal?

    STEP 7. Replace the common rail assembly and fuel injection tubes.

  • After replacing the common rail assembly and fuel injection tubes, re-check the trouble symptoms

    • Q. Does trouble symptom persist?

    Author: admin