Code No. P0403: Exhaust Gas Recirculation Control System










OPERATION



  • Power is supplied to the exhaust gas recirculation valve (terminal No. 2 and No. 5) from the engine control relay (terminal No. 1).
  • The engine-A/T-ECU (terminal No. 3, No. 12, No. 19 and No. 26) makes the power transistor in the unit be in "ON", and that makes currents go on the exhaust gas recirculation valve (terminal No. 1, No. 3, No. 4 and No. 6).

FUNCTION



  • Based on the signal from engine-A/T-ECU, the exhaust gas recirculation valve (stepper motor) controls the exhaust gas recirculation rate.

TROUBLE JUDGMENT


Check Conditions
  • Battery voltage is more than 10.3 V.
  • Ignition switch is in "OFF" from "ON" position.
Judgment Criterion
  • The exhaust gas recirculation valve motor coil surge voltage (system voltage +2 V) is not detected for 3 seconds.
Check Conditions
  • Battery voltage is more than 10.3 V.
  • While the exhaust gas recirculation valve is being driven after the engine has started.
Judgment Criterion
  • The exhaust gas recirculation valve motor coil surge voltage (system voltage +2 V) is not detected for 30 seconds.

PROBABLE CAUSES



  • Failed exhaust gas recirculation valve
  • Open/short circuit in exhaust gas recirculation valve circuit or loose connector contact
  • Failed engine-A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-02 exhaust gas recirculation valve connector

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

STEP 2. Check exhaust gas recirculation valve itself.

  • Check exhaust gas recirculation valve itself [Refer to GROUP 17 - Emission Control System <6G7> - Exhaust Gas Recirculation System - exhaust gas recirculation Valve (stepper motor) Check .

Q. Is the check result normal?
Go to Step 3 .
Replace the exhaust gas recirculation valve (stepper motor).

STEP 3. Perform voltage measurement at B-02 exhaust gas recirculation 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: B-15X engine control relay connector

Q. Is the check result normal?

    Check and repair harness between B-02 (terminal No. 2, No. 5) exhaust gas recirculation valve connector and B-15X (terminal No. 1) engine control relay connector.

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

STEP 5. Perform voltage measurement at D-212 engine-A/T-ECU connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 3, No. 12, No. 19, No. 26 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 7 .
Go to Step 6 .

STEP 6. Connector check: D-212 engine-A/T-ECU connector

Q. Is the check result normal?

    Check and repair harness between B-02 exhaust gas recirculation valve connector and D-212 engine-A/T-ECU connector.

  1. Check harness between B-02 (terminal No. 1) exhaust gas recirculation valve connector and D-212 (terminal No. 3) engine-A/T-ECU connector.
  2. Check harness between B-02 (terminal No. 3) exhaust gas recirculation valve connector and D-212 (terminal No. 12) engine-A/T-ECU connector.
  3. Check harness between B-02 (terminal No. 4) exhaust gas recirculation valve connector and D-212 (terminal No. 19) engine-A/T-ECU connector.
  4. Check harness between B-02 (terminal No. 6) exhaust gas recirculation valve connector and D-212 (terminal No. 26) engine-A/T-ECU connector.

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

STEP 7. Connector check: D-212 engine-A/T-ECU connector

Q. Is the check result normal?
Go to Step 8 .
Repair or replace the connector.

STEP 8. Check harness between B-02 exhaust gas recirculation valve connector and D-212 engine-A/T-ECU connector.

  1. Check harness between B-02 (terminal No. 1) exhaust gas recirculation valve connector and D-212 (terminal No. 3) engine-A/T-ECU connector.
  2. Check harness between B-02 (terminal No. 3) exhaust gas recirculation valve connector and D-212 (terminal No. 12) engine-A/T-ECU connector.
  3. Check harness between B-02 (terminal No. 4) exhaust gas recirculation valve connector and D-212 (terminal No. 19) engine-A/T-ECU connector.
  4. Check harness between B-02 (terminal No. 6) exhaust gas recirculation valve connector and D-212 (terminal No. 26) engine-A/T-ECU connector.

  • Check output line for damage.

Q. Are the check results normal?
Go to Step 9 .
Repair the damaged harness wire.

STEP 9. Connector check: B-15X engine control relay connector

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

STEP 10. Check harness between B-02 (terminal No. 2, No. 5) exhaust gas recirculation valve connector and B-15X (terminal No. 1) engine control relay connector.

  • Check power supply line for damage.

Q. Is the check result normal?
Replace the engine-A/T-ECU.
Repair the damaged harness wire.