Code No. P1020: Mitsubishi Innovative Valve Timing Electronic Control System (MIVEC) Performance Problem








OPERATION



  • Battery voltage is applied to the engine oil pressure switch (for MIVEC) (terminal No. 1) from the engine-ECU (terminal No. 7).

FUNCTION



  • The engine oil pressure switch (for MIVEC) converts the existence of a engine oil pressure into a high/low voltage, and inputs it into the engine-ECU.
  • When the engine oil control valve operates, the engine oil pressure in the MIVEC system rises. The engine oil pressure switch opens, thus interrupting the application of the battery positive voltage. As a result, the output voltage of the engine oil pressure switch (for MIVEC) will fluctuate between 0 and 12 V.
  • The engine-ECU checks whether the engine oil pressure switch (for MIVEC) "OFF" or "ON" during driving.

TROUBLE JUDGEMENT


Check Conditions
  • Engine speed is less than 30 r/min.
  • Engine coolant temperature is 77°C or more
  • Battery voltage is 10 - 16.5 V.
  • 30 seconds or more have passed since the engine starting sequence was completed.
Judgement Criterion
  • Engine oil pressure switch (for MIVEC) has been OFF for 5 seconds.
Check Conditions
  • Engine speed is more than 8,000 r/min.
  • Engine coolant temperature is 77°C or more
  • Battery voltage is 10 - 16.5 V.
  • 30 seconds or more have passed since the engine starting sequence was completed.
Judgement Criterion
  • Engine oil pressure switch (for MIVEC) has been ON for 5 seconds.

PROBABLE CAUSES



  • Failed engine oil pressure switch (for MIVEC)
  • Open/short circuit or harness damage in the engine oil pressure switch (for MIVEC) circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-21 engine oil pressure switch (for MIVEC) connector

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

STEP 2. Perform voltage measurement at B-21 engine oil pressure switch (for MIVEC) connector

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 1 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 8 .
Go to Step 3 .

STEP 3. Perform voltage measurement at B-29 engine-ECU connector.

  • Disconnect engine-ECU connector, and connect special tool power plant ECU check harness (MB992110) to measure at connector for inspection.
  • Disconnect B-21 engine oil pressure switch (for MIVEC) connector.
  • Ignition switch: ON
  • Voltage between terminal No. 7 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 4 .
Go to Step 5 .

STEP 4. Connector check: B-29 engine-ECU connector

Q. Is the check result normal?

    Check and repair harness between B-21 (terminal No. 1) engine oil pressure switch (for MIVEC) connector and B-29 (terminal No. 7) engine-ECU connector.

    • Check output line for open circuit.
Repair or replace the connector.

STEP 5. Connector check: B-29 engine-ECU connector

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

STEP 6. Check harness between B-21 (terminal No. 1) engine oil pressure switch (for MIVEC) connector and B-29 (terminal No. 7) engine-ECU connector.

  • Check output line for short circuit.

Q. Is the check result normal?
Go to Step 7 .
Repair the damaged harness wire.

STEP 7. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code .

Q. Is diagnosis code set?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-ECU.

STEP 8. Perform voltage measurement at B-29 engine-ECU connector.

  • Disconnect engine-ECU connector, and connect special tool power plant ECU check harness (MB992110) to measure at connector for inspection.
  • Voltage between terminal No. 7 and earth.
OK:
    1 V or less (during idling)
    System voltage (engine speed: 5,000 r/min or more)

Q. Is the check result normal?
Go to Step 11 .
Go to Step 9 .

STEP 9. Connector check: B-29 engine-ECU connector

Q. Is the check result normal?
Go to Step 10 .
Repair or replace the connector.

STEP 10. Check harness between B-21 (terminal No. 1) engine oil pressure switch (for MIVEC) connector and B-29 (terminal No. 7) engine-ECU connector.

  • Check output line for damage.

Q. Is the check result normal?
Replace the engine oil pressure switch (for MIVEC).
Repair the damaged harness wire.

STEP 11. Connector check: B-29 engine-ECU connector

Q. Is the check result normal?
Go to Step 7 .
Repair or replace the connector.