Code No. P0489: Exhaust Gas Recirculation (EGR) Valve (stepper motor) Circuit Malfunction (ground short) <Low CO2 specification, FFV>










OPERATION



FUNCTION



TROUBLE JUDGMENT


Check Conditions
Judgement Criterion

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-41 EGR valve connector

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

STEP 2. Perform resistance measurement at B-41 EGR valve connector.

  • Disconnect connector and measure at EGR valve side.
  • Resistance between terminal No. 1 and No. 2.
  • Resistance between terminal No. 2 and No. 3.
  • Resistance between terminal No. 4 and No. 5.
  • Resistance between terminal No. 5 and No. 6.
OK: 20 - 24 Ω (at 20°C)

Q. Are the check results normal?
Go to Step 3 .
Replace the EGR valve.

STEP 3. Perform voltage measurement at B-41 EGR valve connector.

  • Disconnect connector and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 2, No. 5 and earth.
OK: System voltage

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

STEP 4. Connector check: A-33X engine control relay connector

Q. Is the check result normal?

    Check intermediate connector A-11, and repair if necessary. If intermediate connector is normal, check and repair harness between B-41 (terminal No. 2 and No. 5) EGR valve connector and A-33X (terminal No. 2) engine control relay connector.

    • Check power supply line for open/short circuit.
Repair or replace the connector.

STEP 5. Perform voltage measurement at B-08 engine-ECU connector.

  • Disconnect engine-ECU connector, and connect special tool power plant ECU check harness (MB992110) to measure at connector for inspection.
  • Ignition switch: OFF → ON
  • Voltage between terminal No. 31, No. 32, No. 47, No. 48 and earth.
OK: To initialize, energize EGR valve for three seconds and de-energize it.

Q. Is the check result normal?
Go to Step 9 .
Go to Step 6 .

STEP 6. Connector check: B-08 engine-ECU connector

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

STEP 7. Check harness between EGR valve connector and engine-ECU connector.

  1. Check harness between B-41 (terminal No. 1) EGR valve connector and B-08 (terminal No. 31) engine-ECU connector.
  2. Check harness between B-41 (terminal No. 3) EGR valve connector and B-08 (terminal No. 32) engine-ECU connector.
  3. Check harness between B-41 (terminal No. 4) EGR valve connector and B-08 (terminal No. 47) engine-ECU connector.
  4. Check harness between B-41 (terminal No. 6) EGR valve connector and B-08 (terminal No. 48) engine-ECU connector.

  • Check output line for open/short circuit.

Q. Are the check results normal?
Go to Step 8 .
Repair the damaged harness wire.

STEP 8. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

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

STEP 9. Connector check: B-08 engine-ECU connector

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

STEP 10. Check harness between EGR valve connector and engine-ECU connector.

  1. Check harness between B-41 (terminal No. 1) EGR valve connector and B-08 (terminal No. 31) engine-ECU connector.
  2. Check harness between B-41 (terminal No. 3) EGR valve connector and B-08 (terminal No. 32) engine-ECU connector.
  3. Check harness between B-41 (terminal No. 4) EGR valve connector and B-08 (terminal No. 47) engine-ECU connector.
  4. Check harness between B-41 (terminal No. 6) EGR valve connector and B-08 (terminal No. 48) engine-ECU connector.

  • Check output line for damage.

Q. Are the check results normal?
Go to Step 11 .
Repair the damaged harness wire.

STEP 11. Connector check: A-33X engine control relay connector

Q. Is the check result normal?
Go to Step 12 .
Repair or replace the connector.

STEP 12. Check harness between B-41 (terminal No. 2 and No. 5) EGR valve connector and A-33X (terminal No. 2) engine control relay connector.
note Before checking harness, check intermediate connector A-11, and repair if necessary.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 8 .
Repair the damaged harness wire.

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