Dtc P1271 Fuel Regulator Circuit Malfunction (Edu Drive)


DESCRIPTION

MONITOR DESCRIPTION

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

WIRING DIAGRAM

INSPECTION PROCEDURE

READ DTC OUTPUT (DTC P1271 AND/OR P1272)

INSPECT COMMON RAIL ASSEMBLY (PRESSURE DISCHARGE VALVE)

CHECK HARNESS AND CONNECTOR (PRESSURE DISCHARGE VALVE - EDU)

CHECK HARNESS AND CONNECTOR (ECM - EDU)

INSPECT INJECTOR DRIVER (BATTERY VOLTAGE)

INSPECT ECM (PRD VOLTAGE)

REPLACE INJECTOR DRIVER

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

REPLACE COMMON RAIL ASSEMBLY (PRESSURE DISCHARGE VALVE)

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

DTC P1271 Fuel Regulator Circuit Malfunction (EDU Drive)

DTC P1272 Fuel Pressure Regulator Malfunction


DESCRIPTION

HINT:
  1. For more information on the pressure discharge valve and the common rail system (Toyota Fortuner RM0000012WW024X.html).
  2. For more information on the injection driver (EDU) (Toyota Fortuner RM000001AQY01FX.html).
  3. If P1271 and/or P1272 is present, refer to the DTC chart for the fuel system (Toyota Fortuner RM0000012WW024X.html).
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.

Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.1Kd-Ftv Engine Control System.Ecd System. Dtc P1271 Fuel Regulator Circuit Malfunction (Edu Drive)


Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.1Kd-Ftv Engine Control System.Ecd System. Dtc P1271 Fuel Regulator Circuit Malfunction (Edu Drive)


DTC No.
DTC Detection Condition
Trouble Area
P1271
Open or short in pressure discharge valve circuit.
There is no valve opening confirmation (IJF) signal from EDU to ECM despite the ECM sending valve opening command (PRD) signal after the engine is started.
(1 trip detection logic)
  1. Open or short in pressure discharge valve circuit
  2. Open or short in pressure discharge valve itself
  3. EDU
  4. ECM
P1272
Pressure discharge valve closed malfunction.
Actual pressure decreasing rate deviates from the simulated pressure decreasing rate after the ignition switch is turned OFF.
(2 trip detection logic)
  1. Open or short in pressure discharge valve circuit (P1271 is set simultaneously)
  2. Pressure discharge valve
  3. Supply pump
  4. ECM
HINT:
After confirming DTC P1271 and/or P1272, check the fuel pressure inside the common rail in the Powertrain / Engine and ECT / Data List / Fuel Press using the intelligent tester.

Reference:

Engine Speed
Fuel Pressure
Idling
Approximately 30000 to 40000 kPa
3000 rpm (No engine load)
Approximately 30000 to 60000 kPa

MONITOR DESCRIPTION

  1. 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 OFF.

    Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.1Kd-Ftv Engine Control System.Ecd System. Dtc P1271 Fuel Regulator Circuit Malfunction (Edu Drive)

  1. 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. When this occurs, 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 is 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 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.
  1. PULSE GENERATION INSPECTION
    HINT:
    The problem area can be identified by checking the waveform at the following terminals.

    Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.1Kd-Ftv Engine Control System.Ecd System. Dtc P1271 Fuel Regulator Circuit Malfunction (Edu Drive)


    HINT:
    A and D are on the ECM side, and B and C are on the EDU side.

    Malfunction Point
    		Trouble Area
    A
    1. ECM
    B (If A is normal)
    1. Open or short in "PRD (ECM)" - "PRD (EDU)" circuit
    C (If A and B are normal)
    1. Open or short in "RLF+ (EDU)" - "RLF- (EDU)" circuit
    2. Pressure discharge valve
    3. EDU
    D (If A, B and C are normal)
    1. Open or short in "INJF (EDU)" - "INJF (ECM)" circuit (P0200 is set simultaneously)

MONITOR STRATEGY


P1271:
Required sensor
EDU
Frequency of operation
Continuous
Duration
3 seconds
MIL operation
1 driving cycle

P1272:
Required sensors
Fuel pressure sensor
Frequency of operation
Once per driving cycle
Duration
1 second
MIL operation
2 driving cycles

TYPICAL ENABLING CONDITIONS


P1271:
Specification
Drive the vehicle at 50 km/h (31 mph) in 3rd gear and then decelerate by completely releasing the accelerator pedal

P1272:
Item
Specification
Minimum
Maximum
Fuel pressure
30000 kPa (306 kgf/cm2, 4,351 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


P1271:
Specification
There are no confirmation signals from the EDU, despite the ECM sending the command signals regularly during deceleration

P1272:
Specification
The internal pressure stays beyond the specified level after the ignition switch was turned OFF

WIRING DIAGRAM


Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.1Kd-Ftv Engine Control System.Ecd System. Dtc P1271 Fuel Regulator Circuit Malfunction (Edu Drive)


INSPECTION PROCEDURE

NOTICE:
After replacing the ECM, the new ECM needs registration (Toyota Fortuner RM0000012XK030X.html) and initialization (Toyota Fortuner RM0000012X2005X.html).
HINT:
  1. After completing repairs, confirm that P1271 and/or P1272 does not recur.
  2. 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.
  3. Read freeze frame data using the intelligent tester. 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.
1.READ DTC OUTPUT (DTC P1271 AND/OR P1272)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch ON and turn the tester ON.

  1. Enter the following menus: Powertrain / Engine and ECT / DTC.

  1. Read DTCs.

    Result:
    Display (DTC output)
    		Proceed to
    P1271 and/or P1272
    		A
    P1272
    		B


B
Go to step 9
A


2.INSPECT COMMON RAIL ASSEMBLY (PRESSURE DISCHARGE VALVE)


    Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.1Kd-Ftv Engine Control System.Ecd System. Dtc P1271 Fuel Regulator Circuit Malfunction (Edu Drive)

  1. Disconnect the P15 pressure discharge valve connector.

  1. Measure the resistance of the pressure discharge valve.

    Standard resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1 - 2
    		20°C (68°F)
    		0.85 to 1.05 Ω


NG
REPLACE COMMON RAIL ASSEMBLY (Toyota Fortuner RM000002SY500QX.html)
OK


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


    Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.1Kd-Ftv Engine Control System.Ecd System. Dtc P1271 Fuel Regulator Circuit Malfunction (Edu Drive)

  1. Disconnect the I14 and I15 EDU connectors.

  1. Disconnect the P15 pressure discharge valve connector.

  1. Measure the resistance of the wire harness side connectors.

    Standard resistance (Check for open):
    Tester Connection
    		Specified Condition
    RLF+ (I14-4) - P15-2
    		Below 1 Ω
    RLF- (I15-1) - P15-1
    		Below 1 Ω
    Standard resistance (Check for short):
    Tester Connection
    		Specified Condition
    RLF+ (I14-4) or P15-2 - Body ground
    		10 kΩ or higher
    RLF- (I15-1) or P15-1 - Body ground
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


4.CHECK HARNESS AND CONNECTOR (ECM - EDU)


    Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.1Kd-Ftv Engine Control System.Ecd System. Dtc P1271 Fuel Regulator Circuit Malfunction (Edu Drive)

  1. Disconnect the I16 EDU connectors.

  1. Disconnect the E7 ECM connector.

  1. Measure the resistance of the wire harness side connectors.

    Standard resistance (Check for open):
    Tester Connection
    		Specified Condition
    PRD (E7-32) - PRD (I16-2)
    		Below 1 Ω
    INJF (E7-25) - INJF (I16-5)
    		Below 1 Ω
    Standard resistance (Check for short):
    Tester Connection
    		Specified Condition
    PRD (E7-32) or PRD (I16-2) - Body ground
    		10 kΩ or higher
    INJF (E7-25) or INJF (I16-5) - Body ground
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


5.INSPECT INJECTOR DRIVER (BATTERY VOLTAGE)


    Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.1Kd-Ftv Engine Control System.Ecd System. Dtc P1271 Fuel Regulator Circuit Malfunction (Edu Drive)

  1. Disconnect the I14 EDU connector.

  1. Turn the ignition switch ON.

  1. Measure the voltage of the EDU connector.

    Standard voltage:
    Tester Connection
    		Specified Condition
    +B (I14-2) - GND (I14-3)
    		11 to 14 V


NG
CHECK INJECTOR DRIVER POWER SOURCE CIRCUIT (EDU - BATTERY)
OK


6.INSPECT ECM (PRD VOLTAGE)
Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.1Kd-Ftv Engine Control System.Ecd System. Dtc P1271 Fuel Regulator Circuit Malfunction (Edu Drive)

  1. Inspect the ECM using the oscilloscope.

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

  1. Check the waveform between the terminal of the E6 and E7 ECM connectors.

    Standard:
    Tester Connection
    		Specified Condition
    PRD (E7-32) - E1 (E6-7)
    		Correct waveform shown
HINT:
Alternative inspection:
Run the engine at 2500 rpm for 10 seconds and then decrease the engine speed to idling by completely releasing the accelerator pedal.


NG
REPLACE ECM (Toyota Fortuner RM0000013Z0004X.html)
OK


7.REPLACE INJECTOR DRIVER

  1. Replace the injector driver (Toyota Fortuner RM0000046WO00GX.html).


NEXT


8.CHECK IF DTC OUTPUT RECURS (DTC P1271 AND/OR P1272)
HINT:
P1271:
After clearing the DTC, drive the vehicle at 50 km/h (31 mph) in the third gear 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

9.REPLACE COMMON RAIL ASSEMBLY (PRESSURE DISCHARGE VALVE)

  1. Replace common rail assembly (Toyota Fortuner RM000002SY500QX.html).


NEXT


10.CHECK IF DTC OUTPUT RECURS (DTC P1271 AND/OR P1272)
HINT:
P1271:
After clearing the DTC, drive the vehicle at 50 km/h (31 mph) in the third gear 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