Inspection Procedure 20: Intake Air Control Flap System












OPERATION



  • Battery voltage is supplied to the intake air control flap relay (terminal No. 4) and is earthed to the vehicle body from the intake air control flap relay (terminal No. 1).
  • Battery voltage is supplied to the intake air control flap relay (terminal No. 2) from engine control relay (terminal No. 2).
  • Power is supplied to the intake air control flap (terminal No. 3) from the intake air control flap relay (terminal No. 3) and is earthed to the body earth from the intake air control flap (terminal No. 4).
  • The engine-ECU (terminal No. 15) outputs a signal, which is input into the intake air control flap (terminal No. 2).
  • The intake air control flap (terminal No. 1) outputs a signal, which is input into the engine-ECU (terminal No. 40).

FUNCTION



  • Based on the signal from engine-ECU, the intake air control flap controls intake air amount.

PROBABLE CAUSES



  • Failed intake air control flap
  • Open/short circuit or harness damage in intake air control flap circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-02-1 intake air control flap connector

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

STEP 2. Connector check: B-05 engine-ECU connector

Q. Is the check result normal?
Go to Step 3 .
Repair or replace the connector.

STEP 3. Check harness between B-02-1 (terminal No. 1) intake air control flap connector and B-05 (terminal No. 40) engine-ECU connector.
note Before checking harness, check intermediate connector B-02, and repair if necessary

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

Q. Is the check result normal?
Go to Step 4 .
Repair the damaged harness wire.

STEP 4. Perform resistance measurement at B-02-1 intake air control flap.

  • Disconnect connector, and measure at the harness side.
  • Resistance between terminal No. 4 and earth.
OK: Continuity (2 Ω or less)

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

    Check intermediate connectors A-13 and B-02, and repair if necessary. If intermediate connectors are normal, check harness between the B-02-1 (terminal No. 4) intake air control flap connector and body earth.

    • Check earthing line for open circuit and damage.

STEP 5. Connector check: A-21X intake air control flap relay connector

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

STEP 6. Check intake air control flap relay itself.

  • Check intake air control flap relay itself (Refer to ).

Q. Is the check result normal?
Go to Step 7 .
Replace the intake air control flap relay.

STEP 7. Perform voltage measurement at A-21X intake air control flap relay connector.

  • Pull out relay and measure at connector side.
  • Voltage between terminal No. 4 and earth.
OK: System voltage

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

    Check and repair harness between battery and A-21X (terminal No. 4) intake air control flap relay connector.

    • Check power supply line for open/short circuit.

STEP 8. Perform resistance measurement at A-21X intake air control flap relay connector.

  • Remove relay, and measure at relay box side.
  • Resistance between terminal No. 1 and earth.
OK: Continuity (2 Ω or less)

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

    Check and repair harness between A-21X (terminal No. 1) intake air control flap relay connector and body earth.

    • Check earthing line for open circuit and damage.

STEP 9. Perform voltage measurement at A-21X intake air control flap relay connector.

  • Pull out relay and measure at connector side.
  • Ignition switch: ON
  • Voltage between terminal No. 2 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 11 .
Go to Step 10 .

STEP 10. Connector check: A-33X engine control relay connector

Q. Is the check result normal?

    Check and repair harness between A-33X (terminal No. 2) engine control relay connector and A-21X (terminal No. 2) intake air control flap relay connector.

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

STEP 11. Perform voltage measurement at B-02-1 intake air control flap connector.

  • Disconnect connector, and measure at the harness side. Connect the terminal No. 131 of the engine-ECU harness connector to the earth.
  • Ignition switch: ON
  • Voltage between terminal No. 3 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 13 .
Go to Step 12 .

STEP 12. Check harness between A-21X (terminal No. 3) intake air control flap relay connector and B-02-1 (terminal No. 3) intake air control flap connector.
note Before checking harness, check intermediate connectors A-13 and B-02, and repair if necessary

  • Check output line for open/short circuit.

Q. Is the check result normal?

    Check harness between the A-33X (terminal No. 2) engine control relay connector and A-21X (terminal No. 2) intake air control flap relay connector.

    • Check power supply line for damage.
Repair the damaged harness wire.

STEP 13. Check harness between battery and A-21X (terminal No. 4) intake air control flap relay connector.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 14 .
Repair the damaged harness wire.

STEP 14. Check harness between A-21X (terminal No. 3) intake air control flap relay connector and B-02-1 (terminal No. 3) intake air control flap connector.
note Before checking harness, check intermediate connector B-02, and repair if necessary

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 15 .
Repair the damaged harness wire.

STEP 15. Check harness between B-02-1 (terminal No. 2) intake air control flap connector and B-05 (terminal No. 15) engine-ECU connector.
note Before checking harness, check intermediate connector B-02, and repair if necessary

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

Q. Is the check result normal?
Go to Step 16 .
Repair the damaged harness wire.

STEP 16. Replace the intake air control flap.

  • After replacing the intake air control flap, re-check the trouble symptoms.

Q. Does trouble symptom persist?
Replace the engine-ECU.
The check is end.