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Home >> Lexus >> 2024 >> TX 350 Base, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 4 (Hybrid Control System - Diagnostic Codes (4 Of 6)) >> HYBRID CONTROL SYSTEM (for PHEV Model) >> DTC P1F36-31: DC/DC Converter Status Circuit "B" No Signal [12/2023 - ] >> Procedure

DTC P1F36-31: DC/DC Converter Status Circuit "B" No Signal [12/2023 - ]: Procedure

WARNING: This page is about a different car, the 2024 Lexus TX 550h+. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK CONNECTOR CONNECTION CONDITION (HYBRID VEHICLE CONTROL ECU ASSEMBLY CONNECTOR) 

    Refer to PROCEDURE - Step 1

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    CONNECT SECURELY 

    Result: 

    OK 

    See step  2

  2. CHECK CONNECTOR CONNECTION CONDITION (DC/DC CONVERTER ASSEMBLY CONNECTOR) 

    HINT: 

    See step  3

    Result

    Result Proceed to
    OK A
    NG (The connector is not connected securely.) B
    NG (The terminals are not making secure contact or are deformed, or water or foreign matter exists in the connector.) C

    Result: 

    B 

    CONNECT SECURELY 

    Result: 

    C 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    A 

    See step  3

  3. CHECK HYBRID VEHICLE CONTROL ECU ASSEMBLY (CHECK WAVEFORM) 

    Pre-procedure1

    • Turn the ignition switch to ON.
    • Connect an oscilloscope between the hybrid vehicle control ECU assembly terminals specified in the table below, and measure the waveform.
      GTY1234286Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Hybrid Vehicle Control ECU Assembly)      		 - -
      Item Content
      Terminal B88-14 (DFFS) - D117-1 (E1)
      Equipment Setting 5 V/DIV., 5 ms./DIV.
      Condition Ignition switch ON

      OK

      The waveform appears as shown in the illustration.

      HINT: 

      • Perform this inspection with the hybrid vehicle control ECU assembly connector connected.
      • The waveform (duty ratio) differs depending on the operation status of the DC/DC converter assembly and DC/DC converter cooling blower assembly.

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Turn the ignition switch off.

    Result: 

    NG 

    See step  6

    Result: 

    OK 

    See step  4

  4. CLEAR DTC 

    Refer to PROCEDURE - Step 3

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    See step  5

  5. CHECK DTC OUTPUT (HYBRID CONTROL) 

    Pre-procedure1

    • None.
    • Check for DTCs.

      Powertrain > Hybrid Control > Trouble Codes 

      Result

      Result  Proceed to
      P1F36-31 is not output A
      P1F36-31 is output B

    Post-procedure1

    • Turn the ignition switch off.

    Result: 

    A 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [09/2023 - ] 

    Result: 

    B 

    REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

  6. CHECK HYBRID VEHICLE CONTROL ECU ASSEMBLY 
    1. Measure the resistance according to the value(s) in the table below.
      GTY1239957Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Hybrid Vehicle Control ECU Assembly)      		 - -

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      B88-14 (DFFS) - D117-1 (E1) Ignition switch off 70 to 86 kΩ kΩ

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (DC/DC CONVERTER ASSEMBLY - HYBRID VEHICLE CONTROL ECU ASSEMBLY) 
    WARNING:

    Be sure to wear insulated gloves.

    Pre-procedure1

    • Check that the service plug grip is not installed.
      NOTE:

      After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the service information because this may cause a malfunction.

    • Disconnect the DC/DC converter assembly connector.
      GTY1238643Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    • Disconnect the hybrid vehicle control ECU assembly connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      I49-2 (DFFS) - B88-14 (DFFS) Ignition switch off Below 1 Ω Ω
      I49-2 (DFFS) or B88-14 (DFFS) - Body ground and other terminals Ignition switch off 10 kΩ or higher kΩ
    • Turn the ignition switch to ON.
    • Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      J49-2 (DFFS) or B88-14 (DFFS) - Body ground Ignition switch ON Below 1 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the hybrid vehicle control ECU assembly connector.
    • Reconnect the DC/DC converter assembly connector.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (DC/DC CONVERTER ASSEMBLY POWER SUPPLY) 
    WARNING:

    Be sure to wear insulated gloves.

    Pre-procedure1

    • Check that the service plug grip is not installed.
      NOTE:

      After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the service information because this may cause a malfunction.

    • Disconnect the DC/DC converter assembly connector.
      GTY1238643Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    • Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      I49-1 (IGCT) - Body ground Ignition switch ON 11 to 14 V V

      HINT: 

      As there might be an intermittent malfunction in the DC/DC converter assembly power source circuit, inspect the following even if the measured voltage is as specified.

      • Installation condition of fuse(s) (before removing fuse(s)) (Power Source Circuit)
      • Fuse condition (before and after removing fuse(s)) (Power Source Circuit)
      • Connection condition of connectors (Power Source Circuit)
      • Wire harness condition (Power Source Circuit)
      • Wire harness condition (GND circuit)

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the DC/DC converter assembly connector.

    Result: 

    OK 

    REPLACE DC/DC CONVERTER ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    See step  9

  9. INSPECT FUSE (IGCT NO. 3) 

    Pre-procedure1

    • Check installation condition of the IGCT NO. 3 fuse.

      OK

      The fuse is installed securely.

      HINT: 

      If performing a simulation test, turn the ignition switch to ON and gently vibrate the IGCT NO. 3 fuse with a finger before checking for DTCs.

    • Remove the IGCT NO. 3 fuse from the No. 1 luggage room relay block and No. 1 junction block assembly.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      IGCT NO. 3 fuse Always Below 1 Ω Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Install the IGCT NO. 3 fuse.

    Result: 

    NG 

    REPLACE FUSE (IGCT NO. 3) 

    Result: 

    OK 

    See step  10

  10. CHECK HARNESS AND CONNECTOR (NO. 1 LUGGAGE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY - DC/DC CONVERTER ASSEMBLY) 

    Pre-procedure1

    • Remove the IGCT NO. 3 fuse from the No. 1 luggage room relay block and No. 1 junction block assembly.
    • Disconnect the DC/DC converter assembly connector.
      GTY1238643Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition Result
      2 (IGCT NO. 3 fuse) - I49-1 (IGCT) Ignition switch off Below 1 Ω Ω

      Standard Resistance (Check for Short)

      Tester Connection Condition Specified Condition Result
      2 (IGCT NO. 3 fuse) or I49-1 (IGCT) - Body ground and other terminals Ignition switch off 10 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Install the IGCT NO. 3 fuse.
    • Reconnect the DC/DC converter assembly connector.

    Result: 

    OK 

    INSPECT ECU POWER SOURCE CIRCUIT. Refer to  ECU Power Source Circuit [12/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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