Inspection Procedure 18: Variable Geometry Position Sensor System








OPERATION



  • A power voltage of 5 V is applied to the variable geometry position sensor (terminal No. 1) from the engine-ECU (terminal No. 35).
  • The power voltage is earthed to the engine-ECU (terminal No. 53) from the variable geometry position sensor (terminal No. 3).
  • The sensor signal is inputted to the engine-ECU (terminal No. 54) from the variable geometry position sensor output terminal (terminal No. 2).

FUNCTION



  • The variable geometry position sensor detects the position of variable geometry actuator rod and sends the signal to the engine-ECU.
  • Based on the signal, the engine-ECU performs the feedback control of the variable geometry actuator rod.

PROBABLE CAUSES



  • Failed variable geometry position sensor
  • Open/short circuit or harness damage in variable geometry position sensor circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-24 variable geometry position sensor connector

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

STEP 2. Perform voltage measurement at B-24 variable geometry position sensor connector.

  • Disconnect connector, and measure at the harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 1 and earth.
OK: 4.9 - 5.1 V

Q. Is the check result normal?
Go to Step 6 .
Go to Step 3 .

STEP 3. Connector check: B-27 engine-ECU connector

Q. Is the check result normal?
Go to Step 4 .
Repair or replace the connector.

STEP 4. Check harness between B-24 (terminal No. 1) variable geometry position sensor connector and B-27 (terminal No. 35) engine-ECU.

  • Check power supply line for open/short circuit.

Q. Is the check result normal?
Go to Step 5 .
Repair the damaged harness wire.

STEP 5. Check the trouble symptoms.

Q. Does trouble symptom persist?

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

STEP 6. Connector check: B-27 engine-ECU connector

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

STEP 7. Check harness between B-24 (terminal No. 1) variable geometry position sensor connector and B-27 (terminal No. 35) engine-ECU connector.

  • Check power supply line for damage.

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

STEP 8. Perform resistance measurement at B-24 variable geometry position sensor connector.

  • Disconnect connector, and measure at the harness side.
  • Resistance between terminal No. 3 and earth.
OK: Continuity (2 Ω or less)

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

STEP 9. Connector check: B-27 engine-ECU connector

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

STEP 10. Check harness between B-24 (terminal No. 3) variable geometry position sensor connector and B-27 (terminal No. 53) engine-ECU connector.

  • Check earthing line for open circuit and damage.

Q. Is the check result normal?
Go to Step 5 .
Repair the damaged harness wire.

STEP 11. Check harness between B-24 (terminal No. 2) variable geometry position sensor connector and B-27 (terminal No. 54) engine-ECU connector.

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

Q. Is the check result normal?
Go to Step 12 .
Repair the damaged harness wire.

STEP 12. Replace the turbocharger and exhaust manifold assembly.



  • After replacing the turbocharger and exhaust manifold assembly, re-check the trouble symptoms.

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