Inspection Procedure 32: Exhaust Differential Pressure Sensor System










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. 33) and earthed to the engine-ECU (terminal No. 9) from the exhaust differential pressure sensor (terminal No. 2).
  • The sensor signal is inputted to the engine-ECU (terminal No. 21) 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: A-59 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 A-59 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 6 .
Go to Step 3 .

STEP 3. Connector check: B-18 engine-ECU connector


Q. Is the check result normal?

Go to Step 4 .
Repair or replace the connector.

STEP 4. Check harness between A-59 (terminal No. 3) exhaust differential pressure sensor connector and B-18 (terminal No. 33) engine-ECU connector.



  • 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. Perform resistance measurement at A-59 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 9 .
Go to Step 7 .

STEP 7. Connector check: B-18 engine-ECU connector


Q. Is the check result normal?

Go to Step 8 .
Repair or replace the connector.

STEP 8. Check harness between A-59 (terminal No. 2) exhaust differential pressure sensor connector and B-18 (terminal No. 9) 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 9. Connector check: B-18 engine-ECU connector


Q. Is the check result normal?

Go to Step 10 .
Repair or replace the connector.

STEP 10. Check harness between A-59 (terminal No. 3) exhaust differential pressure sensor connector and B-18 (terminal No. 33) engine-ECU connector.



  • Check power supply line for damage.

Q. Is the check result normal?

Go to Step 11 .
Repair the damaged harness wire.

STEP 11. Check harness between A-59 (terminal No. 1) exhaust differential pressure sensor connector and B-18 (terminal No. 21) 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 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.