HYBRID CONTROL SYSTEM, Diagnostic DTC:P0731-871

DTC Code DTC Name
P0731-871 Gear 1 Incorrect Ratio

DESCRIPTION

The power management control ECU uses the B1 and B2 brakes in the hybrid vehicle transmission assembly to switch between low and high gear.

Shifting control is performed using the line pressure circuit, B1 circuit, and B2 circuit. The power management control ECU detects abnormal line pressure by monitoring the operation of the oil pressure switch and oil pressure sensor in each circuit.

Tech Tips

Although the DTC title indicates an incorrect gear ratio, DTC P0731-871 relates to a malfunction of the B2 hydraulic circuit.

A01FRO8E09

Tech Tips


  • The preceding timing chart is for the first "Control the Shift Position" Active Test. The chart will differ for the second or later "Control the Shift Position" Active Test.

  • If "Hi" is selected in the first "Control the Shift Position" Active Test, it may take more time to shift to "Hi".

DTC No. INF Code DTC Detection Condition Trouble Area
P0731 871 Even if the fluid pressure was applied for low gear after the ST-on state occurred, the power management control ECU is not able to confirm that the fluid pressure was applied to the B2 circuit within the specified time.

  • Hybrid vehicle transmission assembly

  • Power management control ECU

  • Wire harness or connector

  • Transmission wire

  • Oil pressure sensor

Tech Tips

ST-on is a state that occurs when the READY indicator in the combination meter blinks after the power switch is pressed with the brake pedal depressed.

WIRING DIAGRAM

A01FUD2E01

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK DTC OUTPUT (HYBRID CONTROL)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

    4. Check if DTCs are output.

      Result
      Result Proceed to
      P0731-871 only is output. A
      Any of the following DTCs are also output. B
      DTC No. Relevant Diagnosis
      P0748-850 Pressure Control Solenoid "A" Electrical (Shift Solenoid Valve (SL1))
      P0778-851 Pressure Control Solenoid "B" Electrical (Shift Solenoid Valve (SL2))
      P06A4-209 Sensor Reference Voltage "D" Circuit Low
      P06A5-210 Sensor Reference Voltage "D" Circuit High

    5. Turn the power switch off.


    B

    GO TO DTC CHART (HYBRID CONTROL SYSTEM) Click here

    A

  2. CHECK CONNECTOR CONNECTION CONDITION (POWER MANAGEMENT CONTROL ECU CONNECTOR)


    1. A01FQC6E01
      Text in Illustration
      *A for LHD
      *B for RHD

      Check the connector connections and contact pressure of the relevant terminals for the power management control ECU connectors Click here.

      OK
      The connectors are connected securely and there are no contact pressure problems.

    NG

    CONNECT SECURELY

    OK

  3. CHECK CONNECTOR CONNECTION CONDITION (TRANSMISSION WIRE CONNECTOR)


    1. A01FQ02

      Check the connection of the transmission wire connector Click here.

      OK
      The connector is connected securely and there are no contact problems.

    NG

    CONNECT SECURELY

    OK

  4. READ VALUE USING GTS (POWER SUPPLY SENSOR VOLTAGE)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Enter the following menus: Powertrain / Hybrid Control / Data List / Power Supply Sensor Voltage.

    4. Read the Data List.

      OK
      Tester Display Switch Condition Specified Condition
      Power Supply Sensor Voltage Power switch on (IG) 4.75 to 5.25 V

    5. Turn the power switch off.


    NG

    REPLACE POWER MANAGEMENT CONTROL ECU Click here

    OK

  5. CHECK POWER MANAGEMENT CONTROL ECU (VOLTAGE)


    1. A01FQNCE12
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Oil Pressure Sensor)

      Disconnect the oil pressure sensor connector.

    2. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      F54-3 (VC) - F54-1 (GND) Power switch on (IG) 4.75 to 5.25 V

    4. Turn the power switch off.

    5. Connect the oil pressure sensor connector.


    NG

    CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - OIL PRESSURE SENSOR) Click here

    NG

  6. READ VALUE USING GTS (B2 OIL PRESSURE SENSOR)


    1. A01FQNCE10
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Oil Pressure Sensor)

      Disconnect the oil pressure sensor connector.

    2. Connect the GTS to the DLC3.

    3. Turn the power switch on (IG).

    4. Enter the following menus: Powertrain / Hybrid Control / Data List / B2 Oil Pressure Sensor.

    5. Read the Data List.

      OK
      Tester Display Condition Specified Condition
      B2 Oil Pressure Sensor F54-2 (VOUT) - F54-3 (VC) ON
      F54-2 (VOUT) is connected to body ground OFF

    6. Turn the power switch off.

    7. Connect the oil pressure sensor connector.


    NG

    CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - OIL PRESSURE SENSOR) Click here

    OK

  7. CHECK HYBRID VEHICLE TRANSMISSION ASSEMBLY (SOLENOID VALVE (SL1), SOLENOID VALVE (SL2))


    1. A01FQZ9E92
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to Power Management Control ECU)

      Disconnect the power management control ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      N91-14 (SL1+) - N91-13 (SL1-) 68°F (20°C) 5.0 to 5.6 Ω
      N91-12 (SL2+) - N91-11 (SL2-) 68°F (20°C) 5.0 to 5.6 Ω

    3. Connect the power management control ECU connector.


    NG

    CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE) Click here

    OK

  8. CHECK HYBRID VEHICLE TRANSMISSION ASSEMBLY (OIL PRESSURE SENSOR)


    1. A01FQZ9E93
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to Power Management Control ECU)

      Disconnect the connector from the power management control ECU.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      N91-25 (VPT1) - N91-24 (PTO1) 68°F (20°C) 1.0 to 4.0 Ω
      N91-24 (PTO1) - N91-23 (EPT1) 68°F (20°C) 5.0 to 10.0 Ω

    3. Connect the power management control ECU connector.


    NG

    REPLACE OIL PRESSURE SENSOR Click here

    OK

  9. CLEAR DTC


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

    4. Read and record the DTCs and freeze frame data.

    5. Clear DTCs and freeze frame data.

    6. Turn the power switch off.


    NEXT

  10. CHECK DTC OUTPUT (HYBRID CONTROL)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (READY).

    3. Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

    4. Check if DTCs are output.

      Result
      Result Proceed to
      P0731-871 is not output. A
      P0731-871 is output. B

      Note

      This DTC is not output when the power switch is on (IG). Therefore, make sure to perform the inspection with the power switch on (READY).

    5. Turn the power switch off.


    B

    REPLACE HYBRID VEHICLE TRANSMISSION ASSEMBLY Click here

    A

  11. CHECK FLUID LEAKS


    1. Check for fluid leaks from the hybrid vehicle transmission assembly.

      OK
      There are no fluid leaks.

    NG

    REPAIR OR REPLACE HYBRID VEHICLE TRANSMISSION ASSEMBLY Click here

    OK

    CHECK FOR INTERMITTENT PROBLEMS Click here

  12. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - OIL PRESSURE SENSOR)


    1. A01FS9GE01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to Power Management Control ECU)
      *b

      Front view of wire harness connector

      (to Oil Pressure Sensor)

      Disconnect the oil pressure sensor connector.

    2. Disconnect the power management control ECU connector.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      N91-25 (VPT1) - F54-3 (VC) Power switch off Below 1 Ω
      N91-24 (PTO1) - F54-2 (VOUT) Power switch off Below 1 Ω
      N91-23 (EPT1) - F54-1 (GND) Power switch off Below 1 Ω
      N91-25 (VPT1) - Body ground Power switch off 10 kΩ or higher
      N91-24 (PTO1) - Body ground Power switch off 10 kΩ or higher
      N91-23 (EPT1) - Body ground Power switch off 10 kΩ or higher

    4. Connect the oil pressure sensor connector.

    5. Connect the power management control ECU connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE POWER MANAGEMENT CONTROL ECU Click here

  13. CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE)


    1. A01FS94E15
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Transmission Wire)

      Disconnect the transmission wire connector.

    2. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      F52-13 (SL1-) - Body ground Power switch on (IG) Below 1 V
      F52-6 (SL1+) - Body ground Power switch on (IG) Below 1 V
      F52-12 (SL2-) - Body ground Power switch on (IG) Below 1 V
      F52-5 (SL2+) - Body ground Power switch on (IG) Below 1 V

      Note

      Turning the power switch on (IG) with the transmission wire connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

    4. Turn the power switch off.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      F52-13 (SL1-) - Body ground Power switch off Below 1 Ω
      F52-6 (SL1+) - Body ground Power switch off Below 1 Ω
      F52-12 (SL2-) - Body ground Power switch off Below 1 Ω
      F52-5 (SL2+) - Body ground Power switch off Below 1 Ω
      F52-13 (SL1-) - Body ground and other terminals Power switch off 10 kΩ or higher
      F52-6 (SL1+) - Body ground and other terminals Power switch off 10 kΩ or higher
      F52-12 (SL2-) - Body ground and other terminals Power switch off 10 kΩ or higher
      F52-5 (SL2+) - Body ground and other terminals Power switch off 10 kΩ or higher

    6. Connect the transmission wire connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE HYBRID VEHICLE TRANSMISSION ASSEMBLY Click here

  14. REPLACE HYBRID VEHICLE TRANSMISSION ASSEMBLY

    Click here


    NEXT

    REPLACE POWER MANAGEMENT CONTROL ECU Click here