RM38T0EC _51 Engine / Hybrid System _115233 STOP AND START _0510781 STOP AND START SYSTEM J

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

·

Air conditioning system

·

Navigation system

·

Electronically controlled brake system

·

Toyota parking assist-sensor system



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 hereEngine / Hybrid System>STOP AND START>STOP AND START SYSTEM>REGISTRATION

·

After replacing the engine stop and start ECU, perform learning of the external backup boost converter (eco run vehicle converter assembly).

Click hereEngine / Hybrid System>STOP AND START>STOP AND START SYSTEM>REGISTRATION

·

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 hereEngine / Hybrid System>STOP AND START>STOP AND START SYSTEM>REGISTRATION

·

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 "General>INTRODUCTION>HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS>ELECTRONIC CIRCUIT INSPECTION PROCEDURE"


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
P323AA2
P323B29
P323B38 		Blinks Converter output voltage cannot be boosted when the engine is restarted A
Auxiliary battery voltage drop
Systems on the converter output side do not operate
B41 terminal: The tire pressure warning system will not operate
B42 terminal: All of the following will not operate
·

Audio and visual system

·

Navigation system


IG41 terminal: All of the following will not operate
·

Tire pressure warning system

·

Toyota parking assist-sensor system

·

Air conditioning system


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) 		P323A19 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)
IGP terminal: All of the following will not operate
·

Power steering system

·

Electronically controlled brake system

·

Tire pressure warning system

·

Toyota parking assist-sensor system

·

Air conditioning system

·

Meter / gauge system


IGR terminal: -
ACC terminal: All of the following will not operate
·

Audio and visual system

·

Navigation system


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)
AC42 terminal: All of the following will not operate
·

Audio and visual system

·

Navigation system


IG12 terminal: The meter / gauge system will not operate
IG31 terminal: All of the following will not operate
·

Power steering system

·

Electronically controlled brake system


IG41 terminal: All of the following will not operate
·

Tire pressure warning system

·

Toyota parking assist-sensor system

·

Air conditioning system


B41 terminal: The tire pressure warning system will not operate
B42 terminal: All of the following will not operate
·

Audio and visual system

·

Navigation system


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

·

Navigation system

·

Power steering system

·

Tire pressure warning system

·

Toyota parking assist-sensor 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
P323AA2
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 (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 (navigation system), system operation is disabled while the ignition switch is ON (Returns to normal when the ignition switch is turned off) C
·

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

·

Communication error DTCs may be stored due to short between AC42 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

·

Short between AC42 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


Result:
Proceed to
A
B
C



A

GO TO DIAGNOSTIC TROUBLE CODE CHART

B

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

C

6.CHECK AUDIO AND VISUAL SYSTEM
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



Result:
Proceed to
OK
NG



OK

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

NG

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

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 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 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 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



Result:
Proceed to
OK
NG



OK

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

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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 Entry and Start System)
Tester Connection Condition Specified Condition
I230-2 (B41) - O124-7 (+B) Always Below 1 Ω
I230-3 (IG41) - O124-1 (IGR) Always Below 1 Ω
I230-2 (B41) - Body ground and other terminals Always 10 kΩ or higher
O124-7 (+B) - Body ground and other terminals Always 10 kΩ or higher
I230-3 (IG41) - Body ground and other terminals Always 10 kΩ or higher
O124-1 (IGR) - Body ground and other terminals Always 10 kΩ or higher

Tire Pressure Warning ECU and Receiver (w/ Smart Entry and Start System)
Tester Connection Condition Specified Condition
I230-2 (B41) - O18-7 (+B) Always Below 1 Ω
I230-3 (IG41) - O18-1 (IGR) Always Below 1 Ω
I230-2 (B41) - Body ground and other terminals Always 10 kΩ or higher
O18-7 (+B) - Body ground and other terminals Always 10 kΩ or higher
I230-3 (IG41) - Body ground and other terminals Always 10 kΩ or higher
O18-1 (IGR) - Body ground and other terminals Always 10 kΩ or higher

Radio and Display Receiver Assembly (w/ Navigation System)
Tester Connection Condition Specified Condition
I230-12 (B42) - I253-4 (+B1) Always Below 1 Ω
I230-26 (AC42) - I253-16 (ACC1) Always Below 1 Ω
I230-12 (B42) - Body ground and other terminals Always 10 kΩ or higher
I253-4 (+B1) - Body ground and other terminals Always 10 kΩ or higher
I230-26 (AC42) - Body ground and other terminals Always 10 kΩ or higher
I253-16 (ACC1) - Body ground and other terminals Always 10 kΩ or higher

Radio and Display Receiver Assembly (w/o Navigation System)
Tester Connection Condition Specified Condition
I230-12 (B42) - I274-4 (+B1) Always Below 1 Ω
I230-26 (AC42) - I274-16 (ACC1) Always Below 1 Ω
I230-12 (B42) - Body ground and other terminals Always 10 kΩ or higher
I274-4 (+B1) - Body ground and other terminals Always 10 kΩ or higher
I230-26 (AC42) - Body ground and other terminals Always 10 kΩ or higher
I274-16 (ACC1) - Body ground and other terminals Always 10 kΩ or higher

Combination Meter Assembly
Tester Connection Condition Specified Condition
I230-10 (IG12) - I4-38 (IG+) Always Below 1 Ω
I230-10 (IG12) - Body ground and other terminals Always 10 kΩ or higher
I4-38 (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

Skid Control ECU (Brake Actuator Assembly)
Tester Connection Condition Specified Condition
I230-23 (IG31) - A151-36 (IGR) Always Below 1 Ω
I230-23 (IG31) - Body ground and other terminals Always 10 kΩ or higher
A151-36 (IGR) - 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



Result:
Proceed to
OK
NG



OK

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

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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
O124-7 (+B) - Body ground*1 Always 10.5 to 16 V
O18-7 (+B) - Body ground*2 Always 10.5 to 16 V
I253-4 (+B1) - Body ground*3 Always 10.5 to 16 V
I274-4 (+B1) - Body ground*4 Always 10.5 to 16 V


*1: w/o Smart Entry and Start System

*2: w/ Smart Entry and Start System

*3: w/ Navigation System

*4: w/o Navigation System



c.

Turn the ignition switch ACC.


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
I253-16 (ACC1) - Body ground*1 Always 10.5 to 16 V
I274-16 (ACC1) - Body ground*2 Always 10.5 to 16 V


*1: w/ Navigation System

*2: w/o Navigation System



e.

Turn the ignition switch to ON.


f.

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
O124-1 (IGR) - Body ground*1 Ignition switch ON 10.5 to 16 V
O18-1 (IGR) - Body ground*2 Ignition switch ON 10.5 to 16 V
I21-1 (IG) - Body ground Ignition switch ON 10.5 to 16 V
A151-36 (IGR) - Body ground Ignition switch ON 10.5 to 16 V
I4-38 (IG+) - Body ground Ignition switch ON 10.5 to 16 V
I24-1 (IG) - Body ground*3 Ignition switch ON 10.5 to 16 V
I37-9 (IG+) - Body ground*4 Ignition switch ON 10.5 to 16 V


*1: w/o Smart Entry and Start System

*2: w/ Smart Entry and Start System

*3: w/ Clearance Sonar System

*4: for Electrical Control Type



Result:
Proceed to
OK
NG



OK

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

NG

REPLACE ENGINE STOP AND START ECU

Click hereEngine / Hybrid System>STOP AND START>ENGINE STOP AND START ECU>REMOVAL


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.


Result:
Proceed to
OK
NG



OK

END

NG

7.CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - RADIO AND DISPLAY RECEIVER ASSEMBLY)
7.CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - RADIO AND DISPLAY RECEIVER ASSEMBLY)
a.

Disconnect the I230 engine stop and start ECU connector.


b.

Disconnect the I253*1 or I274*2 radio and display receiver assembly connector.

*1: w/ Navigation System

*2: w/o Navigation System



c.

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

Standard Resistance:
Tester Connection Condition Specified Condition
I230-12 (B42) - Body ground and other terminals Always 10 kΩ or higher
I253-4 (+B1) - Body ground and other terminals*1 Always 10 kΩ or higher
I274-4 (+B1) - Body ground and other terminals*2 Always 10 kΩ or higher


*1: w/ Navigation System

*2: w/o Navigation System



Result:
Proceed to
OK
NG



OK

GO TO AUDIO AND VISUAL SYSTEM

Click hereAudio / Visual / Telematics>AUDIO / VIDEO>AUDIO AND VISUAL SYSTEM (Production Date from 2023/04)>HOW TO PROCEED WITH TROUBLESHOOTING


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR