ECD SYSTEM(for CCo), Diagnostic DTC:P1271 and P1272

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

DESCRIPTION

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 off to allow prompt discharge of the common rail internal pressure and so that the engine stops smoothly.

Tip:

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

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

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

A208468E01
A205138E01

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

P1271

Fuel Regulator Circuit Malfunction (EDU Drive)

When either condition below is met (1 trip detection logic):

  • Open or short in pressure discharge valve circuit.

  • There is no valve opening confirmation (IJf) signal from the EDU to the ECM for a specific number of times consecutively, despite the ECM sending valve opening command (PRD) signals after the engine is started

  • Open or short in pressure discharge valve circuit

  • Pressure discharge valve (built into common rail assembly)

  • Injector driver (EDU)

Comes on

DTC stored

P1272

Fuel Pressure Regulator Malfunction

Pressure discharge valve does not open.

Actual pressure decreasing rate deviates from the simulated pressure decreasing rate after the ignition switch is turned off.

(2 trip detection logic)

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

  • Pressure discharge valve (built into common rail assembly)

  • Injector driver (EDU)

  • ECM

Comes on

DTC stored
Table 1. Related Data List

DTC No.

Data List

P1271

  • Fuel Press

  • Target Common Rail Pressure

  • Pressure Discharge Valve

P1272
Tip:

  • After confirming DTC P1271 and/or P1272, check the fuel pressure inside the common rail in "Powertrain / Engine and ECT / Data List / Fuel Press" using the GTS.

  • P1271:

    After clearing the DTC, drive the vehicle at 50 km/h (31 mph) in third gear, and then decelerate by releasing the accelerator pedal. Check that P1271 is not stored.

  • P1272:

    After clearing the DTC, start and stop the engine twice (wait 30 seconds or more after turning the ignition switch off before starting the engine the second time), and then confirm that P1272 is not stored.

Table 2. Reference:

Engine Speed

Fuel Pressure (kPa)

Idling

Fuel Press is within +/-5000 kPa of Target Common Rail Pressure

2500 rpm (No engine load)
Table 3. Results of real-vehicle check:

Condition

Fuel Press (Idling)

Fuel Press (1 Second after Engine Stopped)

Pressure discharge valve normal

35000 kPa

170 kPa

Open in pressure discharge valve circuit

34000 kPa

34300 kPa

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 injector driver (EDU) to the ECM, despite the ECM has commanded the injector driver (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 in which a valve is stuck open or closed.

The injector driver (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 injector driver (EDU) interprets this as the IJf signal being low. If this DTC is stored, the ECM enters the fail-safe mode and limits engine power. The fail-safe mode continues until the ignition switch is turned off.

A208469E01

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 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 that the actual drop rate is smaller than the target, the ECM then judges that the valve is stuck closed and stores 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 off.

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

MONITOR STRATEGY

Table 4. P1271:

Required sensors

EDU

Frequency of operation

Continuous

Duration

3 seconds

MIL operation

1 driving cycle
Table 5. P1272:

Required sensors

Fuel pressure sensor

Frequency of operation

Once per driving cycle

Duration

1 second

MIL operation

2 driving cycles

TYPICAL ENABLING CONDITIONS

Table 6. P1271:

Specification

The vehicle is driven at 50 km/h (31 mph) in 3rd gear, and then decelerated by complete release of the accelerator pedal 3 times.
Table 7. P1272:

Item

Specification

Minimum

Maximum

Fuel pressure

30000 kPa (306 kgf/cm2, 4350 psi)

-

Fuel temperature

0°C (32°F)

-

Battery voltage

11 V

-

The monitor will not run if the fuel pressure sensor, pressure discharge valve circuit or fuel temperature sensor is malfunctioning.

TYPICAL MALFUNCTION THRESHOLDS

Table 8. P1271:

Specification

There are no confirmation signals from the injector driver (EDU) for a specific number of times consecutively, despite the ECM sending command signals regularly during deceleration.
Table 9. P1272:

Specification

The internal pressure stays beyond the specified level after the ignition switch is turned off.

CONFIRMATION DRIVING PATTERN

DTC No.

DTC Detection Drive Pattern

P1271

Ignition switch ON to off

and

Drive the vehicle at 50 km/h (31 mph) in third gear, and then decelerate by releasing the accelerator pedal

P1272

Ignition switch ON to off

WIRING DIAGRAM

A210269E04

Refer to DTC P0201 (Click here).

CAUTION / NOTICE / HINT

Note:

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

Tip:

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

  • If P062D and P1271 are present simultaneously, there is an open in the INJF wire harness between the injector driver (EDU) and ECM, or there is an open in the wire harness for both an injector and the pressure discharge valve.

  • Read freeze frame data using the GTS. Freeze frame data records 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, and other data from the time the malfunction occurred.

PROCEDURE

  1. CHECK IF DTC OUTPUT RECURS

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.

      Powertrain > Engine > Clear DTCs

    5. Turn the ignition switch off for 30 seconds or more.

    6. Turn the ignition switch to ON.

    7. Drive the vehicle at 50 km/h (31 mph) in 3rd gear, and then decelerate by completely releasing the accelerator pedal. Perform this 3 times.

    8. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

      Powertrain > Engine > Trouble Codes

    9. Read the pending DTCs.

      Result

      Result

      Proceed to

      DTC P1272 is output

      A

      DTC P1271 is output

      B

      DTC P1271 and P1272 are output

      Other DTCs are output

      C
    B

    INSPECT PRESSURE DISCHARGE VALVEClick here

    C

    GO TO DTC CHART

    Click hereClick here

    A

  2. CHECK COMMON RAIL ASSEMBLY (PRESSURE DISCHARGE VALVE OPERATION)

    1. Inspect the common rail assembly.

      Click here

    Result

    Proceed to

    OK

    NG
    OK

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIREDClick here

    NG

    REPLACE COMMON RAIL ASSEMBLYClick here

  3. INSPECT PRESSURE DISCHARGE VALVE

    1. Inspect the pressure discharge valve.

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE COMMON RAIL ASSEMBLYClick here

    OK

  4. CHECK HARNESS AND CONNECTOR (PRESSURE DISCHARGE VALVE - INJECTOR DRIVER (EDU))

    1. Disconnect the pressure discharge valve connector.

    2. Disconnect the injector driver (EDU) connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      B69-1 - B54-1 (RLF+)

      Always

      Below 1 Ω

      B69-2 - B54-2 (RLF-)

      Always

      Below 1 Ω

      B69-1 or B54-1 (RLF+) - Body ground

      Always

      10 kΩ or higher

      B69-2 or B54-2 (RLF-) - Body ground

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTORClick here

    OK

  5. CHECK HARNESS AND CONNECTOR (INJECTOR DRIVER (EDU) - ECM)

    1. Disconnect the injector driver (EDU) connector.

    2. Disconnect the ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      B53-5 (PRD) - B76-52 (PRD)

      Always

      Below 1 Ω

      B53-1 (RLF) - B76-123 (RLFF)

      Always

      Below 1 Ω

      B53-5 (PRD) or B76-52 (PRD) - Body ground

      Always

      10 kΩ or higher

      B53-1 (RLF) or B76-123 (RLFF) - Body ground

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTORClick here

    OK

  6. CHECK TERMINAL VOLTAGE (POWER SOURCE OF INJECTOR DRIVER (EDU))

    1. A204910C02

      *a

      Front view of wire harness connector

      (to Injector Driver (EDU))

      Disconnect the injector driver (EDU) connectors.

    2. Turn the ignition switch to ON.

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      B51-2 (+B) - B51-4 (GND)

      Ignition switch ON

      11 to 14 V

    Result

    Proceed to

    OK

    NG
    NG

    GO TO INJECTOR CIRCUITClick here

    OK

  7. REPLACE INJECTOR DRIVER (EDU)

    1. Replace the injector driver (EDU).

      Click here

    Result

    Proceed to

    NEXT
    NEXT

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

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.

      Powertrain > Engine > Clear DTCs

    5. Turn the ignition switch off for 30 seconds or more.

    6. Turn the ignition switch to ON.

    7. Drive the vehicle at 50 km/h (31 mph) in 3rd gear, and then decelerate by completely releasing the accelerator pedal. Perform this 3 times.

    8. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

      Powertrain > Engine > Trouble Codes

    9. Read the pending DTCs.

      Tip:

      • If no pending DTCs are output, proceed to the next step to check "All Readiness".

      • Perform the following procedure using the GTS to determine whether or not the DTC judgment has been carried out.

      1. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

        Powertrain > Engine > Utility

        Tester Display

        All Readiness

      2. Input DTC P1271 and P1272.

      3. Check the DTC judgment result.

        Result

        GTS Display

        Result

        Proceed to

        Pending DTC

        DTC P1271 and/or P1272 is output

        B

        All Readiness

        NORMAL

        A

        ABNORMAL

        B
        Tip:

        If STATUS is INCOMPLETE or N/A, perform the following procedure 3 times: drive the vehicle at 50 km/h (31 mph) in 3rd gear, and then decelerate by completely releasing the accelerator pedal.

    A

    END

    B

  9. REPLACE ECM

    1. Replace the ECM.

      Click here

    Result

    Proceed to

    NEXT
    NEXT

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIREDClick here

  10. GO TO INJECTOR CIRCUIT

    1. Go to injector circuit.

      Click here

    Result

    Proceed to

    NEXT
    NEXT

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIREDClick here

  11. REPAIR OR REPLACE HARNESS OR CONNECTOR

    1. Repair or replace the harness or connector.

    Result

    Proceed to

    NEXT
    NEXT

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIREDClick here

  12. REPLACE COMMON RAIL ASSEMBLY

    1. Replace the common rail assembly.

      Click here

    Result

    Proceed to

    NEXT
    NEXT

  13. BLEED AIR FROM FUEL SYSTEM

    1. Bleed the air from the fuel system.

      Click here

    Result

    Proceed to

    NEXT
    NEXT

  14. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.

      Powertrain > Engine > Clear DTCs

    5. Turn the ignition switch off for 30 seconds or more.

    6. Turn the ignition switch to ON.

    7. Drive the vehicle at 50 km/h (31 mph) in 3rd gear, and then decelerate by completely releasing the accelerator pedal. Perform this 3 times.

    8. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

      Powertrain > Engine > Trouble Codes

    9. Confirm that the pending DTC is not output again.

      Tip:

      Perform the following procedure using the GTS to determine whether or not the DTC judgment has been carried out.

      1. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

        Powertrain > Engine > Utility

        Tester Display

        All Readiness

      2. Input DTC P1271 and P1272.

      3. Check the DTC judgment result.

        Tip:

        If STATUS is INCOMPLETE or N/A, perform the following procedure 3 times: drive the vehicle at 50 km/h (31 mph) in 3rd gear, and then decelerate by completely releasing the accelerator pedal.

    Result

    Proceed to

    NEXT
    NEXT

    END