Inspection Procedure 33: Exhaust Differential Pressure Sensor System <Vehicle with DPF>








OPERATION



  • A power voltage of 5 V is applied to the exhaust differential pressure sensor power terminal (terminal No. 3) from the engine-ECU (terminal No. 96) and earthed to the engine-ECU (terminal No. 138) from the exhaust differential pressure sensor (terminal No. 2).
  • The sensor signal is inputted to the engine-ECU (terminal No. 137) from the exhaust differential pressure sensor output terminal (terminal No. 1).

FUNCTION



  • The exhaust differential pressure sensor outputs the voltage to the engine-ECU in accordance with the difference in the voltage between the DPF upstream area and the DPF downstream area.
  • The engine-ECU anticipates the amount of PM accumulated in the DPF through this output voltage.

PROBABLE CAUSES



  • Failed exhaust differential pressure sensor
  • Open/short circuit or harness damage in exhaust differential pressure sensor circuit or loose connector contact

  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-120 exhaust differential pressure sensor connector

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

STEP 2. Perform voltage measurement at B-120 exhaust differential pressure sensor connector.

  • Disconnect connector, and measure at the harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 3 and earth.
OK: 4.9 - 5.1 V

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

STEP 3. Perform voltage measurement at B-28 engine-ECU connector.

  • Disconnect engine-ECU connector, and connect special tool power plant ECU check harness (MB992044) to measure at connector for inspection.
  • Ignition switch: ON
  • Voltage between terminal No. 96 and earth.
OK: 4.9 - 5.1 V

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

STEP 4. Connector check: B-28 engine-ECU connector


Q. Is the check result normal?

    Check intermediate connector A-10, and repair if necessary. If intermediate connector is normal, check and repair harness between B-120 (terminal No. 3) exhaust differential pressure sensor connector and B-28 (terminal No. 96) engine-ECU connector.

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

STEP 5. Connector check: B-28 engine-ECU connector

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

STEP 6. Check harness between B-120 (terminal No. 3) exhaust differential pressure sensor connector and B-28 (terminal No. 96) engine-ECU connector.
note Before checking harness, check intermediate connector A-10, and repair if necessary.

  • Check power supply line for short circuit.

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

STEP 7. 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 8. Perform resistance measurement at B-120 exhaust differential pressure sensor connector.

  • Disconnect connector, and measure at the harness side.
  • Resistance between terminal No. 2 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-28 engine-ECU connector

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

STEP 10. Check harness between B-120 (terminal No. 2) exhaust differential pressure sensor connector and B-28 (terminal No. 138) engine-ECU connector.
note Before checking harness, check intermediate connector A-10, and repair if necessary.

  • Check earthing line for open circuit and damage.

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

STEP 11. Connector check: B-28 engine-ECU connector

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

STEP 12. Check harness between B-120 (terminal No. 3) exhaust differential pressure sensor connector and B-28 (terminal No. 96) engine-ECU connector.
note Before checking harness, check intermediate connector A-10, and repair if necessary.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 13 .
Repair the damaged harness wire.

STEP 13. Check harness between B-120 (terminal No. 1) exhaust differential pressure sensor connector and B-28 (terminal No. 137) engine-ECU connector.
note Before checking harness, check intermediate connector A-10, and repair if necessary.

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

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

STEP 14. Replace the exhaust differential pressure sensor.

  • After replacing the exhaust differential pressure sensor, re-check the trouble symptoms.

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