Code No. P1276: Fuel Filter Exchange <Vehicles with fuel filter pressure switch>




OPERATION



  • The battery voltage is applied to the fuel filter pressure switch (terminal No. 1) from the engine-ECU (terminal No. 110).

FUNCTION



  • The engine-ECU detects the clogged fuel filter by using the fuel filter pressure switch installed on the fuel filter assembly.

TROUBLE JUDGMENT


Check Condition
  • During steady driving after engine warm up.
Judgment Criterion
  • Determination of clogged fuel filter.

PROBABLE CAUSES



  • Failed fuel filter pressure switch
  • Open/short circuit or harness damage in fuel filter pressure switch circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: A-143 fuel filter pressure switch connector

Q. Is the check result normal?

Go to Step 2.

Repair or replace the connector.

STEP 2. Check the fuel filter pressure switch itself.
Check the fuel filter pressure switch itself (Refer to GROUP 13B - Fuel Filter - Fuel Filter Inspection ).

Q. Is the check result normal?
Replace the fuel filter body.
Go to Step 3.

STEP 3. Perform voltage measurement at A-143 fuel filter pressure switch connector.


  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 1 and earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 7.

Go to Step 4.

STEP 4. Connector check: C-103 engine-ECU connector

Q. Is the check result normal?

Go to Step 5.

Repair or replace the connector.

STEP 5. Check harness between A-143 (terminal No. 1) fuel filter pressure switch connector and C-103 (terminal No. 110) engine-ECU connector.



  • Check output line for open/short circuit.

Q. Is the check result normal?

Go to Step 6.

Repair the damaged harness wire.

STEP 6. M.U.T.-III data list

  • Refer to Data List Reference Table .

  1. Item 152: Fuel filter pressure switch

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-ECU. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - Precautions Before Service - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ).

STEP 7. Perform resistance measurement at A-143 fuel filter pressure switch connector.


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

Q. Is the check result normal?

Go to Step 8.


    Check and repair harness between A-143 (terminal No. 2) fuel filter pressure switch connector and body earth.

    • Check earthing line for open circuit and damage.

STEP 8. Connector check: C-103 engine-ECU connector

Q. Is the check result normal?

Go to Step 9.

Repair or replace the connector.

STEP 9. Check harness between A-143 (terminal No. 1) fuel filter pressure switch connector and C-103 (terminal No. 110) engine-ECU connector.



  • Check output line for damage.

Q. Is the check result normal?

Replace the fuel filter.

Repair the damaged harness wire.