STOP AND START SYSTEM(for 3ZR-FAE) Backup Boost Converter Circuit

DESCRIPTION

A backup boost converter is built into the engine stop and start ECU. The backup boost converter helps maintain the power source voltage when the engine is restarted by stop and start control.

This prevents various functions such as the audio and visual system or navigation system from failing if the power source voltage drops due to the battery voltage dropping when the engine is restarted by stop and start control. If a DTC is output, troubleshoot the DTC first.

Tech Tips

A relay function and fuse function are provided in the backup boost converter.

If there is a malfunction in any of the electrical system circuits connected to the backup boost converter, the fuse and relay functions shut off the malfunctioning circuit to protect other circuits (remains shut off until next trip).

When the electrical system circuit is shut off, power to the circuit is cut off, causing any systems connected to the circuit to be disabled.

The fuse function is reset* when the ignition switch is turned off. If the malfunction still exists in the electrical system circuit that has been shut off by the relay function, it will be shut off again by the relay and fuse functions the next time the ignition switch is turned to ON.

*: A semiconductor fuse self-resets according to electric signals.


    The backup boost converter supplies power to:

  • Main body ECU (multiplex network body ECU)

  • Skid control ECU (Brake actuator assembly)

  • Spiral with sensor cable sub-assembly

  • Power steering ECU assembly

  • Combination meter assembly

  • Radio receiver assembly, radio and display receiver assembly or navigation receiver assembly

  • Inner rear view mirror assembly

  • Lane departure warning camera

  • Tire pressure warning ECU and receiver

  • Blind spot monitor sensor LH

  • Blind spot monitor sensor RH

  • Parking assist ECU

  • Driving support ECU assembly

  • Millimeter wave radar sensor assembly

  • Network Gateway ECU

WIRING DIAGRAM

Click here

CAUTION / NOTICE / HINT

Note


  • for CVT:

    When replacing the engine stop and start ECU with a new one, make sure to download the previous status (number of starter operations) of the old engine stop and start ECU. After replacing the engine stop and start ECU, turn the ignition switch to ON and wait 20 seconds, then confirm that "OK" is displayed for the Data List item "Oper Prohibition (O/P Air Bleeding)". Then upload the previous status (number of starter operations) to the engine stop and start ECU.

    Click here

  • for Manual Transaxle:

    Before replacing the engine stop and start ECU, read the number of starter operations and write it into a new engine stop and start ECU.

    Click here

  • After replacing the engine stop and start ECU or air conditioning amplifier assembly, reset and perform learning of the air conditioning information in the engine stop and start ECU.

    Click here

  • After replacing the engine stop and start ECU or airbag sensor assembly, clear and calibrate the deceleration sensor zero point in the engine stop and start ECU.

    Click here

  • Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE


  1. CHECK PROBLEM SYMPTOMS


    1. Determine the trouble area by referring to the table below.

      Effect on Vehicle Trouble Area/Cause Fail-safe DTC Output Stop and start cancel indicator light Symptom Proceed to

        When the engine is restarted by stop and start control, the following symptoms may occur.

      • The audio and visual system or navigation system is reset

      • The combination meter assembly fades out

      • The steering wheel feels heavy when the engine is restarted*

        *: A DTC may be stored in the power steering system

      Backup boost converter internal malfunction


      • Internal power source malfunction

      • Internal power source overvoltage

      • Duty error

      • Communication cycle error

      		 Stop and start control prohibited P323B Blinks Converter output voltage cannot be boosted when the engine is restarted A
      Battery voltage drop

      Systems on the converter output side do not operate


        B41 terminal:

      • Parking assist ECU


        B42 terminal: All of the following will not operate

      • Radio receiver assembly

      • Navigation receiver assembly

      • Radio and display receiver assembly


        IG41 terminal: All of the following will not operate

      • Inner rear view mirror assembly

      • Lane departure warning camera

      • Tire pressure warning ECU and receiver

      • Blind spot monitor sensor LH

      • Blind spot monitor sensor RH

      • Network gateway ECU

      • Millimeter wave radar sensor assembly

      • Driving support ECU assembly

      • Parking assist ECU

      • Systems whose power is supplied from the main body ECU (multiplex network body ECU)


        OP21 Terminal(for CVT):

      • Oil pump assembly with motor (continuously variable transaxle assembly)

      		 Overcurrent applied to an output terminal (output terminal relay circuit is shutoff)

      Stop and start control is prohibited

      (Connected ECUs or sensors may detect power source malfunction DTCs)

      		 B22C0 Blinks Systems do not operate as power supply from the converter is cut off A

      Systems do not operate

      (Due to converter input side malfunction)


        IG1 terminal: All of the following do not operate

      • Brake actuator assembly

      • Spiral with sensor cable sub-assembly

      • Power steering ECU assembly

      • Inner rear view mirror assembly

      • Lane departure warning camera

      • Tire pressure warning ECU and receiver

      • Blind spot monitor sensor LH

      • Blind spot monitor sensor RH

      • Network gateway ECU

      • Millimeter wave radar sensor assembly

      • Driving support ECU assembly

      • Systems whose power is supplied from the main body ECU (multiplex network body ECU)


        IG2 terminal:

      • The combination meter assembly will not function


        ACC terminal: All of the following will not operate

      • Radio receiver assembly

      • Navigation receiver assembly

      • Radio and display receiver assembly

      • Parking assist ECU

      Converter input circuit malfunction


      • Open or short to GND in IG1 circuit

      • Open or short to GND in IG2 circuit

      • Open or short to GND in ACC circuit

      		 Stop and start control prohibited - Does not blink (Blinks when communication error DTCs are stored) Systems do not operate as power supply from the converter is cut off B

      Systems on the converter output side do not operate

      (varies depending on the malfunctioning relay circuit the converter detected)


        AC41 terminal:

      • The radio receiver assembly will not function

      • The navigation receiver assembly will not function

      • The radio and display receiver assembly will not function

      • The parking assist ECU will not function


        IG11 terminal:

      • The power steering ECU assembly will not function


        IG12 terminal:

      • The combination meter assembly will not function


        IG31 terminal:

      • The brake actuator assembly will not function

      • The spiral with sensor cable sub-assembly will not function

      Malfunction in circuits the converter supplies power to

      (between the converter and ECUs or sensors)


      • Open or short in the combination meter assembly circuit

      		 Related systems do not operate as the relay circuit in the converter is turned off - Does not blink (Blinks when communication error DTCs are stored) Systems do not operate as power supply from the converter is cut off B

        All of the following will operate

      • Inner rear view mirror assembly

      • Lane departure warning camera

      • Tire pressure warning ECU and receiver

      • Blind spot monitor sensor LH

      • Blind spot monitor sensor RH

      • Network gateway ECU

      • Millimeter wave radar sensor assembly

      • Driving support ECU assembly

      • Parking assist ECU

      • Systems whose power is supplied from the main body ECU (multiplex network body ECU)

      • Open in BBC fuse circuit

      • Short in converter circuit

      • Backup boost converter malfunction

      		 Stop and start control prohibited P0617 Does not blink (Due to disabled meter/gauge system) All systems that the converter supplies power to do not operate (see circuit diagram) A
      P323B

      The audio and visual system or navigation system does not function

      (until the ignition switch is turned off)

      Excessive audio volume

      Data List item "State of BBC" displays "BBC Overcurrent" while the circuit is protected

      		 The relay circuit in the converter is turned off to cut off power supply to the audio and visual system or navigation system (Returns to normal when the ignition switch is turned off) - Does not blink

      If overcurrent is detected in the audio and visual system or navigation system, system operation is disabled while the ignition switch is ON

      (Returns to normal when the ignition switch is turned off)

      		 C

      • The radio receiver assembly, navigation receiver assembly, radio and display receiver assembly or parking assist ECU cannot be turned off (short between AC41 and +B)

      • The combination meter assembly cannot be turned off (short between IG12 and +B)

      • Communication error DTCs may be stored due to short between IG31 and +B

      Tech Tips

      Varies depending on the number of times an open occurs in the +B circuit

      Converter circuit malfunction


      • Short between AC41 and +B

      • Short between IG12 and +B

      • Short between IG31 and +B

      		 - - Does not blink The converter cannot shut off power source when the ignition switch is turned off B

      Ignition switch does not turn to ACC (short between ACC and +B)

      Ignition switch does not turn off (short between IG1 or IG2 and +B)

      Engine stop and start ECU power source circuit malfunction


      • Short between ACC and +B

      • Short between IG1 and +B

      • Short between IG2 and +B

      		 - - Does not blink

      • Ignition switch does not turn to ACC

      • Ignition switch does not turn off

      		 B
      Result
      Proceed to
      A
      B
      C

    A

    GO TO DIAGNOSTIC TROUBLE CODE CHART Click here

    C

    CHECK AUDIO AND VISUAL SYSTEM OR NAVIGATION SYSTEM Click here

    B

  2. CHECK ENGINE STOP AND START ECU (POWER SOURCE CIRCUIT)


    1. B002AECC24
      *a

      Front view of wire harness connector

      (to Engine Stop and Start ECU)

      Disconnect the engine stop and start ECU connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A86-1 (BIN2) - Body ground Always 9.5 to 14 V
      A86-3 (BIN1) - Body ground Always 9.5 to 14 V

    3. Turn the ignition switch ACC.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      G87-19 (ACC) - Body ground Ignition switch ACC 9.5 to 14 V

    5. Turn the ignition switch to ON.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      G87-18 (IG2) - Body ground Ignition switch ON 9.5 to 14 V
      G87-21 (IG1) - Body ground Ignition switch ON 9.5 to 14 V

    7. Turn the ignition switch off.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      G87-18 (IG2) - Body ground Ignition switch off 0 to 1 V
      G87-19 (ACC) - Body ground Ignition switch off 0 to 1 V
      G87-21 (IG1) - Body ground Ignition switch off 0 to 1 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - EACH ECU OR SENSOR)


    1. Disconnect the connector from the corresponding system ECU/sensor.

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

      Standard Resistance
      Radio Receiver Assembly (for Radio Receiver Type)
      Tester Connection Condition Specified Condition
      G87-12 (B42) - G46-4 (+B1) Always Below 1 Ω
      G87-24 (AC41) - G46-3 (ACC1) Always Below 1 Ω
      G87-12 (B42) - Body ground Always 10 kΩ or higher
      G87-24 (AC41) - Body ground Always 10 kΩ or higher
      G46-4 (+B1) - Body ground Always 10 kΩ or higher
      G46-3 (ACC1) - Body ground Always 10 kΩ or higher
      Navigation Receiver Assembly (for Navigation Receiver Type)
      Tester Connection Condition Specified Condition
      G87-12 (B42) - G137-4 (+B1) Always Below 1 Ω
      G87-24 (AC41) - G137-3 (ACC1) Always Below 1 Ω
      G87-12 (B42) - Body ground Always 10 kΩ or higher
      G87-24 (AC41) - Body ground Always 10 kΩ or higher
      G137-4 (+B1) - Body ground Always 10 kΩ or higher
      G137-3 (ACC1) - Body ground Always 10 kΩ or higher
      Radio and Display Receiver Assembly (for Radio and Display Receiver Type)
      Tester Connection Condition Specified Condition
      G87-12 (B42) - G141-4 (+B1) Always Below 1 Ω
      G87-24 (AC41) - G141-3 (ACC1) Always Below 1 Ω
      G87-12 (B42) - Body ground Always 10 kΩ or higher
      G87-24 (AC41) - Body ground Always 10 kΩ or higher
      G141-4 (+B1) - Body ground Always 10 kΩ or higher
      G141-3 (ACC1) - Body ground Always 10 kΩ or higher
      Brake Actuator Assembly
      Tester Connection Condition Specified Condition
      G87-1 (IG31) - A80-12 (IG1) Always Below 1 Ω
      G87-1 (IG31) - Body ground Always 10 kΩ or higher
      A80-12 (IG1) - Body ground Always 10 kΩ or higher
      Spiral with Sensor Cable Sub-assembly
      Tester Connection Condition Specified Condition
      G87-1 (IG31) - G12-4 (IG) Always Below 1 Ω
      G87-1 (IG31) - Body ground Always 10 kΩ or higher
      G12-4 (IG) - Body ground Always 10 kΩ or higher
      Power Steering ECU Assembly
      Tester Connection Condition Specified Condition
      G87-6 (IG11) - h1-1 (IG) Always Below 1 Ω
      G87-6 (IG11) - Body ground Always 10 kΩ or higher
      h1-1 (IG) - Body ground Always 10 kΩ or higher
      Combination Meter Assembly
      Tester Connection Condition Specified Condition
      G87-10 (IG12) - G16-39 (IG+) Always Below 1 Ω
      G87-10 (IG12) - Body ground Always 10 kΩ or higher
      G16-39 (IG+) - Body ground Always 10 kΩ or higher
      Instrument Panel Junction Block Assembly (Main Body ECU (Multiplex Network Body ECU))
      Tester Connection Condition Specified Condition
      G87-3 (IG41) - 3D-40 (IG) Always Below 1 Ω
      G87-3 (IG41) - Body ground Always 10 kΩ or higher
      3D-40 (IG) - Body ground Always 10 kΩ or higher
      Inner Rear View Mirror Assembly (w/ EC mirror without Lane Departure Alert System)
      Tester Connection Condition Specified Condition
      G87-3 (IG41) - Q14-1 (IG) Always Below 1 Ω
      G87-3 (IG41) - Body ground Always 10 kΩ or higher
      Q14-1 (IG) - Body ground Always 10 kΩ or higher
      Inner Rear View Mirror Assembly (w/ EC mirror with Lane Departure Alert System)
      Tester Connection Condition Specified Condition
      G87-3 (IG41) - Q15-4 (IG) Always Below 1 Ω
      G87-3 (IG41) - Body ground Always 10 kΩ or higher
      Q15-4 (IG) - Body ground Always 10 kΩ or higher
      Lane Departure Warning Camera (w/ Lane Departure Alert System)
      Tester Connection Condition Specified Condition
      G87-3 (IG41) - Q17-7 (IGB) Always Below 1 Ω
      G87-3 (IG41) - Body ground Always 10 kΩ or higher
      Q17-7 (IGB) - Body ground Always 10 kΩ or higher
      Tire Pressure Warning ECU and Receiver (w/ Tire Pressure Warning System)
      Tester Connection Condition Specified Condition
      G87-3 (IG41) - M30-1 (IG) Always Below 1 Ω
      G87-3 (IG41) - Body ground Always 10 kΩ or higher
      M30-1 (IG) - Body ground Always 10 kΩ or higher
      Blind Spot Monitor Sensor LH (w/ Blind Spot Monitor System)
      Tester Connection Condition Specified Condition
      G87-3 (IG41) - R1-5 (BLB) Always Below 1 Ω
      G87-3 (IG41) - Body ground Always 10 kΩ or higher
      R1-5 (BLB) - Body ground Always 10 kΩ or higher
      Blind Spot Monitor Sensor RH (w/ Blind Spot Monitor System)
      Tester Connection Condition Specified Condition
      G87-3 (IG41) - T1-5 (BRB) Always Below 1 Ω
      G87-3 (IG41) - Body ground Always 10 kΩ or higher
      T1-5 (BRB) - Body ground Always 10 kΩ or higher
      Network Gateway ECU
      Tester Connection Condition Specified Condition
      G87-3 (IG41) - G170-11 (IG1) Always Below 1 Ω
      G87-3 (IG41) - Body ground Always 10 kΩ or higher
      G170-11 (IG1) - Body ground Always 10 kΩ or higher
      Millimeter Wave Radar Sensor Assembly (w/ Dynamic Radar Cruise Control System)
      Tester Connection Condition Specified Condition
      G87-3 (IG41) - Z6-8 (IGB) Always Below 1 Ω
      G87-3 (IG41) - Body ground Always 10 kΩ or higher
      Z6-8 (IGB) - Body ground Always 10 kΩ or higher
      Driving Support ECU Assembly (w/ Dynamic Radar Cruise Control System)
      Tester Connection Condition Specified Condition
      G87-3 (IG41) - G168-7 (B) Always Below 1 Ω
      G87-3 (IG41) - Body ground Always 10 kΩ or higher
      G168-7 (B) - Body ground Always 10 kΩ or higher
      Parking Assist ECU (w/ Panoramic View Monitor System)
      Tester Connection Condition Specified Condition
      G87-3 (IG41) - a2-6 (IG) Always Below 1 Ω
      G87-24 (AC41) - a2-1 (ACC) Always Below 1 Ω
      G87-2 (B41) - a2-2 (+B) Always Below 1 Ω
      G87-3 (IG41) - Body ground Always 10 kΩ or higher
      a2-6 (IG) - Body ground Always 10 kΩ or higher
      G87-24 (AC41) - Body ground Always 10 kΩ or higher
      a2-1 (ACC) - Body ground Always 10 kΩ or higher
      G87-2 (B41) - Body ground Always 10 kΩ or higher
      a2-2 (+B) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK ENGINE STOP AND START ECU (EACH ECU OR SENSOR POWER SOURCE CIRCUIT)


    1. Disconnect the connector from the corresponding system ECU/sensor.

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

      Tech Tips

      Measure the voltage at the corresponding terminals.

      Standard Voltage
      Radio Receiver Assembly (for Radio Receiver Type)
      Tester Connection Condition Specified Condition
      G46-4 (+B1) - Body ground Always 10.5 to 16 V
      Navigation Receiver Assembly (for Navigation Receiver Type)
      Tester Connection Condition Specified Condition
      G137-4 (+B1) - Body ground Always 10.5 to 16 V
      Radio and Display Receiver Assembly (for Radio and Display Receiver Type)
      Tester Connection Condition Specified Condition
      G141-4 (+B1) - Body ground Always 10.5 to 16 V
      Parking Assist ECU (w/ Panoramic View Monitor System)
      Tester Connection Condition Specified Condition
      a2-2 (+B) - Body ground Always 10.5 to 16 V

    3. Turn the ignition switch to ACC.

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

      Tech Tips

      Measure the voltage at the corresponding terminals.

      Standard Voltage
      Radio Receiver Assembly (for Radio Receiver Type)
      Tester Connection Switch Condition Specified Condition
      G46-3 (ACC1) - Body ground Ignition switch ACC 10.5 to 16 V
      Navigation Receiver Assembly (for Navigation Receiver Type)
      Tester Connection Switch Condition Specified Condition
      G137-3 (ACC1) - Body ground Ignition switch ACC 10.5 to 16 V
      Radio and Display Receiver Assembly (for Radio and Display Receiver Type)
      Tester Connection Switch Condition Specified Condition
      G141-3 (ACC1) - Body ground Ignition switch ACC 10.5 to 16 V
      Parking Assist ECU (w/ Panoramic View Monitor System)
      Tester Connection Condition Specified Condition
      a2-1 (ACC) - Body ground Ignition switch ACC 10.5 to 16 V

    5. Turn the ignition switch to ON.

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

      Tech Tips

      Measure the voltage at the corresponding terminals.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      3D-40 (IG) - Body ground Ignition switch ON 10.5 to 16 V
      Q14-1 (IG) - Body ground*1 Ignition switch ON 10.5 to 16 V
      Q15-4 (IG) - Body ground*2 Ignition switch ON 10.5 to 16 V
      M30-1 (IG) - Body ground*3 Ignition switch ON 10.5 to 16 V
      G170-11 (IG1) - Body ground Ignition switch ON 10.5 to 16 V
      Z6-8 (IGB) - Body ground*4 Ignition switch ON 10.5 to 16 V
      G168-7 (B) - Body ground*4 Ignition switch ON 10.5 to 16 V
      Q17-7 (IGB) - Body ground*5 Ignition switch ON 10.5 to 16 V
      R1-5 (BLB) - Body ground*6 Ignition switch ON 10.5 to 16 V
      T1-5 (BRB) - Body ground*6 Ignition switch ON 10.5 to 16 V
      a2-6 (IG) - Body ground*7 Ignition switch ON 10.5 to 16 V
      G16-39 (IG+) - Body ground Ignition switch ON 10.5 to 16 V
      h1-1 (IG) - Body ground Ignition switch ON 10.5 to 16 V
      A80-12 (IG1) - Body ground Ignition switch ON 10.5 to 16 V
      G12-4 (IG) - Body ground Ignition switch ON 10.5 to 16 V

      • *1: w/ EC Mirror without Lane Departure Alert System

      • *2: w/ EC Mirror with Lane Departure Alert System

      • *3: w/ Tire Pressure Warning System

      • *4: w/ Dynamic Radar Cruise Control System

      • *5: w/ Lane Departure Alert System

      • *6: w/ Blind Spot Monitor System

      • *7: w/ Panoramic View Monitor System

      Result
      Proceed to
      OK
      NG

    OK

    CHECK POWER SOURCE CIRCUIT (POWER SOURCE CIRCUIT OF RELATED SYSTEM)

    NG

    REPLACE ENGINE STOP AND START ECU Click here

  5. CHECK AUDIO AND VISUAL SYSTEM OR NAVIGATION SYSTEM


    1. Turn the ignition switch off and wait for 1 minute.

    2. Turn the ignition switch to ON.

    3. Lower the audio volume.

    4. for Radio Receiver Type/Radio and Display Receiver Type:

      Check if the audio and visual system operates normally.

      OK
      Audio and visual system operates normally.

    5. for Navigation Receiver Type:

      Check if the navigation system operates normally.

      OK
      Navigation system operates normally.
      Result
      Proceed to
      NG
      OK

    OK

    END

    NG

  6. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - RADIO AND DISPLAY RECEIVER)


    1. Disconnect the G87 engine stop and start ECU connector.

    2. for Radio Receiver Type:

      Disconnect the G46 radio receiver assembly connector.

    3. for Navigation Receiver Type:

      Disconnect the G137 navigation receiver assembly connector.

    4. for Radio and Display Receiver Type:

      Disconnect the G141 radio and display receiver assembly connector.

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

      Standard Resistance
      for Radio Receiver Type:
      Tester Connection Condition Specified Condition
      G87-12 (B42) - Body ground Always 10 kΩ or higher
      G46-4 (+B1) - Body ground Always 10 kΩ or higher
      G87-24 (AC41) - Body ground Always 10 kΩ or higher
      G46-3 (ACC1) - Body ground Always 10 kΩ or higher
      for Navigation Receiver Type:
      Tester Connection Condition Specified Condition
      G87-12 (B42) - Body ground Always 10 kΩ or higher
      G137-4 (+B1) - Body ground Always 10 kΩ or higher
      G87-24 (AC41) - Body ground Always 10 kΩ or higher
      G137-3 (ACC1) - Body ground Always 10 kΩ or higher
      for Radio and Display Receiver Type:
      Tester Connection Condition Specified Condition
      G87-12 (B42) - Body ground Always 10 kΩ or higher
      G141-4 (+B1) - Body ground Always 10 kΩ or higher
      G87-24 (AC41) - Body ground Always 10 kΩ or higher
      G141-3 (ACC1) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK (for Radio Receiver Type/Radio and Display Receiver Type)
      OK (for Navigation Receiver Type)
      NG

    OK (for Radio Receiver Type/Radio and Display Receiver Type)

    GO TO AUDIO AND VISUAL SYSTEM for Radio Receiver Type: Click here
    GO TO AUDIO AND VISUAL SYSTEM for Radio and Display Receiver Type: Click here

    OK (for Navigation Receiver Type)

    GO TO NAVIGATION SYSTEM Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR