Toyota Corolla Cross Owners & Service Manuals

Toyota Corolla Cross: Backup Boost Converter Circuit

Toyota Corolla Cross (2022-2024) Service Manual / Engine & Hybrid System / Stop And Start / Stop And Start System / 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 from malfunctioning if the power source voltage drops due to the auxiliary battery voltage dropping when the engine is restarted by stop and start control.

If any DTCs are output, troubleshoot the DTCs first.

HINT:

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 signal.

The backup boost converter supplies power to:
  • Meter / gauge system
  • Power steering system
  • Audio and visual system
  • Tire pressure warning system
  • Toyota Safety Sense
  • Parking support brake system

WIRING DIAGRAM

Refer to DTC P323A00.

Click here

CAUTION / NOTICE / HINT

NOTICE:

  • 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, perform learning of the external backup boost converter (eco run vehicle converter assembly).

    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

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

HINT:

For wire harness and connector inspection procedures and precautions, refer to " "

PROCEDURE

1.

CHECK PROBLEM SYMPTOMS

(a) 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

Symptom

Proceed to

When the engine is restarted by stop and start control:

The following symptoms may occur

  • Audio and visual system is reset
  • The combination meter assembly fades out

Backup boost converter internal malfunction

  • Internal power source malfunction
  • Internal power source overvoltage
  • Duty error
  • Communication cycle error

Stop and start control prohibited

P323A00

P323B14

P323B29

P323B38

Does not come on (For Mexico Models: Blinks)

Converter output voltage cannot be boosted when the engine is restarted

A

Auxiliary battery voltage drop

Systems do not operate

(Due to converter input side malfunction)

IGR terminal: All of the following will not operate

  • Power steering system
  • Tire pressure warning system
  • Toyota Safety Sense
  • Parking support brake system

IGP terminal: The meter / gauge system will not operate

ACC terminal: The Audio and visual system will not operate

Converter input circuit malfunction

  • Open or short to GND in IGR circuit
  • Open or short to GND in IGP 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)

IG12 terminal: The meter / gauge system will not operate

IG31 terminal: The power steering system will not operate

IG41 terminal: All of the following will not operate

  • Tire pressure warning system
  • Toyota Safety Sense
  • Parking support brake system

B41 terminal: The tire pressure warning system will not operate

Malfunction in circuits the converter supplies power to

(between the converter and ECUs or sensors)

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 systems do not operate

  • Audio and visual system
  • Power steering system
  • Tire pressure warning system
  • Toyota Safety Sense
  • Parking support brake system
  • Meter / gauge system
  • Open in BBC fuse circuit
  • Short in converter circuit
  • Backup boost converter malfunction

Stop and start control prohibited

P061519

Does not blink (Due to disabled meter / gauge system)

All systems that the converter supplies power to do not operate (see circuit diagram)

A

P30DF62

P30EF4B

P323A00

P323A16

P323B14

P323B29

P323B38

The audio does not operate (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 (Returns to normal when the ignition switch is turned off)

-

Does not blink

If overcurrent is detected in the audio and visual system, system operation is disabled while the ignition switch is ON (Returns to normal when the ignition switch is turned off)

C

The external backup boost converter (eco run vehicle converter assembly) output side system does not operate

  • Audio and visual system
  • Open in BBC fuse circuit
  • Malfunction in circuits the converter supplies power to
  • External backup boost converter (eco run vehicle converter assembly) malfunction

-

-

Does not blink

All systems that the converter supplies power to do not operate (see circuit diagram)

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

HINT:

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

Converter circuit malfunction

  • Short between IG12 and +B

-

-

Does not blink

The converter cannot shut off the power source when the ignition switch is turned off

B
  • Ignition switch cannot be turned off from ACC (short between ACC and +B)
  • Ignition switch cannot be turned off from ON (short between IGP or IGR and +B)

Engine stop and start ECU power source circuit malfunction

  • Short between ACC and +B
  • Short between IGP and +B
  • Short between IGR and +B

-

-

Does not blink
  • Ignition switch does not turn ACC
  • Ignition switch cannot be turned off

B
A

GO TO DIAGNOSTIC TROUBLE CODE CHART
C

GO TO STEP 6

D

GO TO STEP 7

B

2.

CHECK HARNESS AND CONNECTOR (BIN1 AND BIN2 TERMINALS POWER SOURCE CIRCUIT)

(a) Disconnect the A168 engine stop and start ECU connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A168-1 (BIN2) - Body ground

Always

9.5 to 14 V

A168-3 (BIN1) - Body ground

Always

9.5 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE STOP AND START ECU - AUXILIARY BATTERY)
OK

3.

CHECK HARNESS AND CONNECTOR (IGR, IGP AND ACC TERMINALS POWER SOURCE CIRCUIT)

(a) Disconnect the I230 engine stop and start ECU connector.

(b) Turn the ignition switch ACC.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

I230-19 (ACC) - Body ground

Ignition switch ACC

9.5 to 14 V

(d) Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

I230-21 (IGR) - Body ground

Ignition switch ON

9.5 to 14 V

I230-18 (IGP) - Body ground

Ignition switch ON

9.5 to 14 V

(f) Turn the ignition switch to off.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

I230-19 (ACC) - Body ground

Ignition switch off

0 to 1 V

I230-21 (IGR) - Body ground

Ignition switch off

0 to 1 V

I230-18 (IGP) - Body ground

Ignition switch off

0 to 1 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

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

(a) Disconnect the connector from the corresponding system ECU/sensor.

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

Standard Resistance:

Tire Pressure Warning ECU and Receiver (w/o Smart Key System)

Tester Connection

Condition

Specified Condition

I230-2 (B41) - O221-7 (+B)

Always

Below 1 Ω

I230-3 (IG41) - O221-1 (IGR)

Always

Below 1 Ω

I230-2 (B41) - Body ground and other terminals

Always

10 kΩ or higher

O221-7 (+B) - Body ground and other terminals

Always

10 kΩ or higher

I230-3 (IG41) - Body ground and other terminals

Always

10 kΩ or higher

O221-1 (IGR) - Body ground and other terminals

Always

10 kΩ or higher

Tire Pressure Warning ECU and Receiver (w/ Smart Key System)

Tester Connection

Condition

Specified Condition

I230-2 (B41) - O209-7 (+B)

Always

Below 1 Ω

I230-3 (IG41) - O209-1 (IGR)

Always

Below 1 Ω

I230-2 (B41) - Body ground and other terminals

Always

10 kΩ or higher

O209-7 (+B) - Body ground and other terminals

Always

10 kΩ or higher

I230-3 (IG41) - Body ground and other terminals

Always

10 kΩ or higher

O209-1 (IGR) - Body ground and other terminals

Always

10 kΩ or higher

Combination Meter Assembly

Tester Connection

Condition

Specified Condition

I230-10 (IG12) - I4-6 (IG+)

Always

Below 1 Ω

I230-10 (IG12) - Body ground and other terminals

Always

10 kΩ or higher

I4-6 (IG+) - Body ground and other terminals

Always

10 kΩ or higher

Power Steering ECU Assembly

Tester Connection

Condition

Specified Condition

I230-23 (IG31) - I21-1 (IG)

Always

Below 1 Ω

I230-23 (IG31) - Body ground and other terminals

Always

10 kΩ or higher

I21-1 (IG) - Body ground and other terminals

Always

10 kΩ or higher

Clearance Warning ECU Assembly (w/ Clearance Sonar System)

Tester Connection

Condition

Specified Condition

I230-3 (IG41) - I24-1 (IG)

Always

Below 1 Ω

I230-3 (IG41) - Body ground and other terminals

Always

10 kΩ or higher

I24-1 (IG) - Body ground and other terminals

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

5.

CHECK ENGINE STOP AND START ECU (OUTPUT VOLTAGE FOR EACH SYSTEM)

(a) Disconnect the connector from the corresponding system ECU/sensor.

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

HINT:

Measure the voltage at the corresponding terminals.

Standard Voltage:

Tester Connection

Condition

Specified Condition

O221-7 (+B) - Body ground*1

Always

10.5 to 16 V

O209-7 (+B) - Body ground*2

Always

10.5 to 16 V
  • *1: w/o Smart Key System
  • *2: w/ Smart Key System

(c) Turn the ignition switch to ON.

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

HINT:

Measure the voltage at the corresponding terminals.

Standard Voltage:

Tester Connection

Condition

Specified Condition

O221-1 (IGR) - Body ground*1

Ignition switch ON

10.5 to 16 V

O209-1 (IGR) - Body ground*2

Ignition switch ON

10.5 to 16 V

I24-1 (IG) - Body ground*3

Ignition switch ON

10.5 to 16 V
  • *1: w/o Smart Key System
  • *2: w/ Smart Key System
  • *3: w/ Clearance Sonar System
OK

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

REPLACE ENGINE STOP AND START ECU

6.

CHECK AUDIO AND VISUAL SYSTEM

(a) Turn the ignition switch off and wait for 1 minute.

(b) Turn the ignition switch to ON.

(c) Lower the audio volume.

(d) Check if the audio and visual system operates normally.

OK:

Audio and visual system operates normally.

OK

END
NG

GO TO AUDIO AND VISUAL SYSTEM

7.

CHECK HARNESS AND CONNECTOR (BIN TERMINAL POWER SOURCE CIRCUIT)

(a) Disconnect the A166 external backup boost converter (eco run vehicle converter assembly) connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A166-11 (BIN) - Body ground

Always

9.5 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (EXTERNAL BACKUP BOOST CONVERTER (ECO RUN VEHICLE CONVERTER ASSEMBLY) - AUXILIARY BATTERY)
OK

8.

CHECK HARNESS AND CONNECTOR (ACC TERMINAL POWER SOURCE CIRCUIT)

(a) Disconnect the A166 external backup boost converter (eco run vehicle converter assembly) connector.

(b) Turn the ignition switch to ACC.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

A166-3 (ACC) - Body ground

Ignition switch ACC

9.5 to 14 V

(d) Turn the ignition switch to off.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

A166-3 (ACC) - Body ground

Ignition switch off

0 to 1 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

9.

CHECK HARNESS AND CONNECTOR (EXTERNAL BACKUP BOOST CONVERTER (ECO RUN VEHICLE CONVERTER ASSEMBLY) - BODY GROUND)

(a) Disconnect the external backup boost converter (eco run vehicle converter assembly) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A166-6 (GND) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

10.

CHECK HARNESS AND CONNECTOR (EXTERNAL BACKUP BOOST CONVERTER (ECO RUN VEHICLE CONVERTER ASSEMBLY) - STEREO COMPONENT AMPLIFIER ASSEMBLY)

(a) Disconnect the external backup boost converter (eco run vehicle converter assembly) connector.

(b) Disconnect the stereo component amplifier assembly connector.

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

Standard Resistance:

Stereo Component Equalizer Assembly

Tester Connection

Condition

Specified Condition

A166-5 (BO1) - I233-1 (+B)

Always

Below 1 Ω

A166-5 (BO1)or I233-1 (+B) - Body ground and other terminals

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

11.

CHECK EXTERNAL BACKUP BOOST CONVERTER (ECO RUN VEHICLE CONVERTER ASSEMBLY) (OUTPUT VOLTAGE FOR STEREO COMPONENT AMPLIFIER ASSEMBLY)

(a) Disconnect the stereo component amplifier assembly connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

I233-1 (+B) - Body ground

Ignition switch ACC

10.5 to 16 V
OK

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

REPLACE EXTERNAL BACKUP BOOST CONVERTER (ECO RUN VEHICLE CONVERTER ASSEMBLY)

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