ECD SYSTEM (w/o DPF), Diagnostic DTC:P1271, P1272

DTC Code DTC Name
P1271 Fuel Regulator Circuit Malfunction (EDU Drive)
P1272 Fuel Pressure Regulator Malfunction

DESCRIPTION

Tech Tips


  • For more information on the pressure discharge valve and the common rail system Click here.

  • For more information on the injection driver (EDU) Click here.

  • If P1271 and/or P1272 is present, refer to the DTC chart for the fuel system Click here.

The ECM controls the internal fuel pressure of the common rail by opening and closing the pressure discharge valve. When sudden deceleration occurs, the internal fuel pressure will temporarily become higher than usual and combustion noise may result. Therefore the ECM will open the valve temporarily to discharge the excess pressure inside the common rail. Also, the pressure discharge valve opens when the ignition switch is turned to OFF to allow prompt discharge of the common rail internal pressure.

A01BBFCE01
A01BA8CE01
DTC No. DTC Detection Condition Trouble Area
P1271

Open or short in pressure discharge valve circuit

No valve opening confirmation (IJF) signal from EDU to ECM despite ECM sending valve opening command (PRD) signal after engine started

(1 trip detection logic)

  • Open or short in pressure discharge valve circuit

  • Pressure discharge valve (common rail assembly)

  • EDU

  • ECM
P1272

Pressure discharge valve closed malfunction.

Actual pressure decreasing rate deviates from simulated pressure decreasing rate after ignition switch OFF.

(2 trip detection logic)

  • Open or short in pressure discharge valve circuit (P1271 set simultaneously)

  • Pressure discharge valve (common rail assembly)

  • ECM

Tech Tips

After confirming DTC P1271 and/or P1272, check the fuel pressure inside the common rail in the Powertrain / Engine / Data List / Fuel Press using an intelligent tester.

Reference
Engine Speed Fuel Pressure (MPa)
Idling Approximately 30 to 40
3,000 rpm (No engine load) Approximately 85 to 105

MONITOR DESCRIPTION

P1271 (Open or short in pressure discharge valve circuit):

This DTC will be set if there is no valve opening confirmation (IJF) signal sent from the EDU to the ECM even though the ECM has commanded the EDU to open the pressure discharge valve. This DTC refers to an open or short circuit malfunction of the pressure discharge valve circuit, not a malfunction that includes a valve that is stuck open or closed.

The EDU monitors the current supplied to the pressure discharge valve to verify that the current flows into the valve. If the current exceeds the specified level, the EDU determines that the IJF signal is low. If this DTC is present, the ECM enters the fail-safe mode and limits engine power. The fail-safe mode continues until the ignition switch is turned to OFF.

A01BH62E02
P1272 (Closed malfunction of the pressure discharge valve):

The pressure discharge valve will open and discharge the internal fuel pressure from the common rail to the fuel tank when the ignition switch is turned to OFF. In this event, the ECM compares the actual drop rate of the internal fuel pressure and the target drop rate. If the ECM judges the actual drop rate is smaller than the target, the ECM then judges that the valve has stuck closed and sets this DTC. This DTC will be stored if the internal fuel pressure does not drop to the target after the ignition switch has been turned to OFF.

If this DTC is present, the ECM enters a fail-safe mode and limits engine power. The fail-safe mode continues until the ignition switch is turned OFF.

WIRING DIAGRAM

A01BHN8E01

INSPECTION PROCEDURE

Note

After replacing the ECM, the new ECM needs registration Click here and initialization Click here.

Tech Tips


  • After completing repairs, confirm that P1271 and/or P1272 does not recur.

  • If P0200 and P1271 are present simultaneously, there is an open circuit in the INJF wire harness between the EDU and ECM, or in the wire harness for both injector and pressure discharge valve.

  • Read freeze frame data using an intelligent tester. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data, from the time the malfunction occurred.

PROCEDURE


  1. READ DTC OUTPUT (DTC P1271 AND/OR P1272)


    1. Connect an intelligent tester to the DLC3.

    2. Turn the ignition switch to ON and turn the tester ON.

    3. Select the following menu items: Powertrain / Engine / DTC.

    4. Read DTCs.

      Result
      Display (DTC Output) Proceed To
      P1271 and/or P1272 A
      P1272 B

    B

    REPLACE COMMON RAIL ASSEMBLY (PRESSURE DISCHARGE VALVE) Click here

    A

  2. INSPECT COMMON RAIL ASSEMBLY (PRESSURE DISCHARGE VALVE)


    1. A01BFIJE07

      Disconnect the D64 pressure discharge valve connector.

    2. Measure the resistance of the pressure discharge valve.

      Standard resistance
      Tester Connection Specified Condition
      1 - 2

      0.85 to 1.05 Ω

      at 20°C (68°F)

    3. Reconnect the pressure discharge valve connector.


    NG

    REPLACE COMMON RAIL ASSEMBLY

    OK

  3. CHECK HARNESS AND CONNECTOR (PRESSURE DISCHARGE VALVE - EDU)


    1. A01BAD0E01

      Disconnect the B40 and B41 EDU connectors.

    2. Disconnect the D64 pressure discharge valve connector.

    3. Check the resistance.

      Standard resistance (Check for open)
      Tester Connection Specified Condition
      COM3 (B40-3) - D64-2 Below 1 Ω
      PRV (B41-3) - D64-1 Below 1 Ω
      Standard resistance (Check for short)
      Tester Connection Specified Condition
      COM3 (B40-3) or D64-2 - Body ground 10 kΩ or higher
      PRV (B41-3) or D64-1 - Body ground 10 kΩ or higher

    4. Reconnect the pressure discharge valve connector.

    5. Reconnect the EDU connectors.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK HARNESS AND CONNECTOR (ECM - EDU)


    1. A01BEDTE03

      Disconnect the B41 and B42 EDU connectors.

    2. Disconnect the D1 ECM connector.

    3. Check the resistance.

      Standard resistance (Check for open)
      Tester Connection Specified Condition
      PRD (D1-32) - PRD (B42-5) Below 1 Ω
      INJF (D1-25) - INJF (B41-1) Below 1 Ω
      Standard resistance (Check for short)
      Tester Connection Specified Condition
      PRD (D1-32) or PRD (B42-5) - Body ground 10 kΩ or higher
      INJF (D1-25) or INJF (B41-1) - Body ground 10 kΩ or higher

    4. Reconnect the ECM connector.

    5. Reconnect the EDU connectors.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. INSPECT INJECTOR DRIVER (EDU) (POWER SOURCE)


    1. A01BHNME02

      Disconnect the B40 and B42 EDU connectors.

    2. Turn the ignition switch to ON.

    3. Measure the voltage between the terminals of the EDU connectors.

      Standard voltage
      Tester Connection Specified Condition
      +B (B40-6) - GND (B42-4) 11 to 14 V

    4. Reconnect the EDU connectors.


    NG

    CHECK INJECTOR DRIVER POWER SOURCE CIRCUIT (EDU - BATTERY)

    OK

  6. INSPECT ECM (PRD VOLTAGE)

    A01BG31E03

    1. Inspect the ECM using the oscilloscope.

    2. Drive the vehicle at 50 km/h (31 mph) with the third gear (M/T) or second gear (A/T), and then decelerate by quickly releasing the accelerator pedal.

    3. Check the waveform between the terminal of the D1 and D3 ECM connectors.

      Standard
      Tester Connection Specified Condition
      PRD (D1-32) - E1 (D3-7) Correct waveform shown

      Tech Tips

      Alternative inspection:

      Run the engine at 2,500 rpm for 10 seconds and then decrease the engine speed to idling by completely releasing the accelerator pedal.


    NG

    REPLACE ECM

    OK

  7. REPLACE INJECTOR DRIVER (EDU)


    NEXT

  8. CHECK WHETHER DTC OUTPUT RECURS (DTC P1271 AND/OR P1272)

    Tech Tips

    P1271:

    After clearing the DTC, drive the vehicle at 50 km/h (31 mph) with the third gear (M/T) or second gear (A/T), and then decelerate by quickly releasing the accelerator pedal. Confirm that DTC P1271 is not present again.

    P1272:

    After clearing the DTC, start and stop the engine twice, and then confirm that DTC P1272 is not present again.


    NEXT

    END

  9. REPLACE COMMON RAIL ASSEMBLY (PRESSURE DISCHARGE VALVE)

    Replace common rail assembly Click here.


    NEXT

  10. CHECK WHETHER DTC OUTPUT RECURS (DTC P1271 AND/OR P1272)

    Tech Tips

    P1271:

    After clearing the DTC, drive the vehicle at 50 km/h (31 mph) with the third gear (M/T) or second gear (A/T), and then decelerate by releasing the accelerator pedal. Confirm that DTC P1271 is not present again.

    P1272:

    After clearing the DTC, start and stop the engine twice, and then confirm that DTC P1272 is not present again.


    NEXT

    END