Backup Boost Converter Circuit [12/2024 - ]: Procedure

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	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	P323A-00 P323B-29 P323B-38	Does not come on	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: All of the following will not operate The tire pressure warning system Digital rear-view mirror system B42 terminal: - B43 terminal: - IG41 terminal: All of the following will not operate Tire pressure warning system Air conditioning system Intuitive parking assist system	Overcurrent applied to an output terminal (output terminal relay circuit is shutoff)	-	X087A	Does not come on	Systems do not operate as power supply from the converter is cut off	E
   Systems do not operate (Due to converter input side malfunction) IGP terminal: All of the following will not operate Tire pressure warning system Power steering system Air conditioning system Intuitive parking assist system Electronically controlled brake system Meter / gauge system IGR terminal: - ACC terminal: -	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: - 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 Air conditioning system Intuitive parking assist system Stabilizer with disconnection mechanism system B41 terminal: All of the following will not operate The tire pressure warning system Digital rear-view mirror system B42 terminal: - B43 terminal: -	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 Tire pressure warning system Air conditioning system Intuitive parking assist system Power steering system Electronically controlled brake system Meter / gauge system Digital rear-view mirror system	Open in BBC fuse circuit Short in converter circuit Backup boost converter malfunction	Stop and start control prohibited	P0615-11	Does not blink (Due to disabled meter / gauge system)	All systems that the converter supplies power to do not operate (see circuit diagram)	A
   			P323A-00 P323A-16 P323B-14 P323B-29 P323B-38
   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*1 The Data List "State of External BBC" displays "Overload" while an excessive volume circuit is protected*2	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 external backup boost converter (eco run vehicle converter assembly) output side system does not operate Navigation system Audio and visual system	Open in TIRE INF/BBC NO. 3 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) 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

   *1: w/o External Backup Boost Converter (EcoRun Vehicle Converter Assembly)*2: w/ External Backup Boost Converter (EcoRun Vehicle Converter Assembly)

   Result

   Proceed to
   A
   B
   C
   D
   E

Result: 

A 

GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer To  DIAGNOSTIC TROUBLE CODE CHART [12/2024 - ] 

Result: 

C 

See step  5

Result: 

D 

See step  7

Result: 

E 

See step  13

Result: 

B 

See step  2

1. 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
   A23-1 (BIN2) - Body ground	Always	9.5 to 14 V
   A23-3 (BIN1) - Body ground	Always	9.5 to 14 V

3. Turn the ignition switch to ACC.
4. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   K70-19 (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
   K70-21 (IGR) - Body ground	Ignition switch ON	9.5 to 14 V
   K70-18 (IGP) - Body ground	Ignition switch ON	9.5 to 14 V

7. Turn the headlight dimmer switch (light control switch) to the tail or head position.
8. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   K70-20 (ILL) - Body ground	Headlight dimmer switch (light control switch) in tail or head position	9.5 to 14 V

9. Turn the ignition switch off.
10. Measure the voltage according to the value(s) in the table below.

    Standard Voltage

    Tester Connection	Condition	Specified Condition
    K70-21 (IGR) - Body ground	Ignition switch off	0 to 1 V
    K70-19 (ACC) - Body ground	Ignition switch off	0 to 1 V
    K70-18 (IGP) - Body ground	Ignition switch off	0 to 1 V

    Result

    Proceed to
    OK
    NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  3

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

   TIRE PRESSURE WARNING SYSTEM
   
   

   Tester Connection	Condition	Specified Condition
   K70-3 (IG41) - T17-1 (IGR)	Always	Below 1 Ω
   K70-2 (B41) - T17-7 (+B)	Always	Below 1 Ω
   K70-3 (IG41) - Body ground	Always	10 kΩ or higher
   T17-1 (IGR) - Body ground	Always	10 kΩ or higher
   K70-2 (B41) - Body ground	Always	10 kΩ or higher
   T17-7 (+B) - Body ground	Always	10 kΩ or higher

   CLEARANCE WARNING ECU ASSEMBLY
   
   

   Tester Connection	Condition	Specified Condition
   K70-3 (IG41) - K58-1 (IG)	Always	Below 1 Ω
   K70-3 (IG41) - Body ground	Always	10 kΩ or higher
   K58-1 (IG) - Body ground	Always	10 kΩ or higher

   AIR CONDITIONING CONTROL ASSEMBLY
   
   

   Tester Connection	Condition	Specified Condition
   K70-3 (IG41) - K23-1 (IG+)	Always	Below 1 Ω
   K70-3 (IG41) - Body ground	Always	10 kΩ or higher
   K23-1 (IG+) - Body ground	Always	10 kΩ or higher

   POWER STEERING ECU
   
   

   Tester Connection	Condition	Specified Condition
   K70-23 (IG31) - D1-4 (IG)	Always	Below 1 Ω
   K70-23 (IG31) - Body ground	Always	10 kΩ or higher
   D1-4 (IG) - Body ground	Always	10 kΩ or higher

   SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY)
   
   

   Tester Connection	Condition	Specified Condition
   K70-23 (IG31) - A18-45 (IGR)	Always	Below 1 Ω
   K70-23 (IG31) - Body ground	Always	10 kΩ or higher
   A18-45 (IGR) - Body ground	Always	10 kΩ or higher

   COMBINATION METER ASSEMBLY
   
   

   Tester Connection	Condition	Specified Condition
   K70-10 (IG12) - K4-6 (IG+)	Always	Below 1 Ω
   K70-10 (IG12) - Body ground	Always	10 kΩ or higher
   K4-6 (IG+) - Body ground	Always	10 kΩ or higher

   INNER REAR VIEW MIRROR ASSEMBLY
   
   

   Tester Connection	Condition	Specified Condition
   K70-2 (B41) - X12-6 (+B)	Always	Below 1 Ω
   K70-2 (B41) - Body ground	Always	10 kΩ or higher
   X12-6 (+B) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Disconnect the connector from the corresponding system ECU/sensor.
2. 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
   T17-7 (+B) - Body ground	Always	10.5 to 16 V
   X12-6 (+B) - Body ground	Always	10.5 to 16 V

3. Turn the ignition switch to ON.
4. 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
   K4-6 (IG+) - Body ground	Ignition switch ON	10.5 to 16 V
   D1-4 (IG) - Body ground	Ignition switch ON	10.5 to 16 V
   A18-45 (IGR) - Body ground	Ignition switch ON	10.5 to 16 V
   T17-1 (IGR) - Body ground	Ignition switch ON	10.5 to 16 V
   K23-1 (IG+) - Body ground	Ignition switch ON	10.5 to 16 V
   K58-1 (IG) - Body ground	Ignition switch ON	10.5 to 16 V

   Result

   Proceed to
   OK
   NG

Result: 

OK 

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

Result: 

NG 

REPLACE ENGINE STOP AND START ECU ASSEMBLY 

Refer to REMOVAL [12/2024 - ]

1. Turn the ignition switch off and wait for 1 minute.
2. Turn the ignition switch to ON.
3. Lower the audio volume.
4. Check if the audio and visual system operates normally.

   OK

   Audio and visual system operates normally.

   Result

   Result	Proceed to
   OK	A
   NG (w/o External Backup Boost Converter (Eco Run Vehicle Converter Assembly))	B
   NG (w/ External Backup Boost Converter (Eco Run Vehicle Converter Assembly))	C

Result: 

A 

END 

Result: 

B 

GO TO AUDIO AND VISUAL SYSTEM 

Refer to "AUDIO AND VISUAL SYSTEM". Refer To AUDIO AND VISUAL SYSTEM

Result: 

C 

See step  6

1. Disconnect the external backup boost converter (eco run vehicle converter assembly) connector.
2. Disconnect the stereo component amplifier assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A1-5 (BO1) - Body ground and other terminals	Always	10 kΩ or higher
   T6-1 (+B) - Body ground and other terminals	Always	10 kΩ or higher
   T6-16 (+B2) - Body ground and other terminals	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

OK 

GO TO AUDIO AND VISUAL SYSTEM 

Refer to "AUDIO AND VISUAL SYSTEM". Refer To AUDIO AND VISUAL SYSTEM

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

1. Disconnect the external backup boost converter (eco run vehicle converter assembly) connector.
2. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A1-11 (BIN) - Body ground	Always	9.5 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

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

Result: 

OK 

See step  8

1. Disconnect the external backup boost converter (eco run vehicle converter assembly) connector.
2. Turn the ignition switch to ACC.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A1-3 (ACC) - Body ground	Ignition switch ACC	9.5 to 14 V

4. Turn the ignition switch off.
5. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A1-3 (ACC) - Body ground	Ignition switch off	0 to 1 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

See step  12

Result: 

OK 

See step  9

1. Disconnect the external backup boost converter (eco run vehicle converter assembly) connector.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A1-6 (GND) - Body ground	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  10

1. Disconnect the external backup boost converter (eco run vehicle converter assembly) connector.
2. Disconnect the connector from the corresponding system ECU/sensor.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A1-5 (BO1) - T6-1 (+B)	Always	Below 1 Ω
   A1-5 (BO1) - T6-16 (+B2)	Always	Below 1 Ω
   A1-5 (BO1) or T6-1 (+B) - Body ground and other terminals	Always	10 kΩ or higher
   A1-5 (BO1) or T6-16 (+B2) - Body ground and other terminals	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  11

1. Disconnect the connector from the corresponding system ECU/sensor.
2. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   T6-1 (+B) - Body ground	Ignition switch ACC	10.5 to 16 V
   T6-16 (+B2) - Body ground	Ignition switch ACC	10.5 to 16 V

   Result

   Proceed to
   OK
   NG

Result: 

OK 

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

Result: 

NG 

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

Refer to REMOVAL [12/2024 - ]

1. Disconnect the external backup boost converter (eco run vehicle converter assembly) connector.
2. Disconnect the power distribution box assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A1-3 (ACC) - K94-6	Always	Below 1 Ω
   A1-3 (ACC) or K94-6 - Body ground and other terminals	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE POWER DISTRIBUTION BOX ASSEMBLY 

Refer to REMOVAL [12/2024 - ]

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Pre-procedure1

1. Disconnect the engine stop and start ECU connector.
2. Remove the BBC NO. 1 and BBC NO. 2 fuses from the NO. 1 engine room relay block and junction block assembly.

   Procedure1

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A23-1 (BIN2) - BBC NO. 2 fuse terminal 2	Always	Below 1 Ω
   A23-3 (BIN1) - BBC NO. 1 fuse terminal 2	Always	Below 1 Ω
   A23-1 (BIN2) - Body ground	Always	10 kΩ or higher
   BBC NO. 2 fuse terminal 2 - Body ground	Always	10 kΩ or higher
   A23-3 (BIN1) - Body ground	Always	10 kΩ or higher
   BBC NO. 1 fuse terminal 2 - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

   Post-procedure1

4. None.

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  14

Pre-procedure1

1. Disconnect the engine stop and start ECU connector.
2. Disconnect the tire pressure warning ECU and receiver connector.
3. Disconnect the clearance warning ECU assembly connector.
4. Disconnect the NO. 2 air conditioning control assembly connector.
5. Disconnect the inner rear view mirror assembly connector.

   Procedure1

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   K70-3 (IG41) - T17-1 (IGR)	Always	Below 1 Ω
   K70-3 (IG41) - K23-1 (IG+)	Always	Below 1 Ω
   K70-3 (IG41) - K58-1 (IG)	Always	Below 1 Ω
   K70-2 (B41) - T17-7 (+B)	Always	Below 1 Ω
   K70-2 (B41) - X12-6 (+B)	Always	Below 1 Ω
   K70-3 (IG41) - Body ground	Always	10 kΩ or higher
   K70-2 (B41) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

   Post-procedure1

7. None.

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  15

Pre-procedure1

1. Disconnect the engine stop and start ECU connectors.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component without harness connected (Engine Stop and Start ECU)

   -

   -

   Procedure1

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   K70-3 (IG41) - A24-6 (DGND)	Always	10 kΩ or higher
   K70-2 (B41) - A24-6 (DGND)	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

   Post-procedure1

3. None.

Result: 

NG 

REPLACE ENGINE STOP AND START ECU ASSEMBLY 

Refer to REMOVAL [12/2024 - ]

Result: 

OK 

See step  16

1. Check that additional devices installed to the vehicle (aftermarket audio system, etc.) are not connected to the B41 or IG41 terminal circuit of the engine stop and start ECU.

   Result

   Result	Proceed to
   Load from an additional device installed to the vehicle (aftermarket audio system, etc.) is not applied.	A
   Load from an additional device installed to the vehicle (aftermarket audio system, etc.) is applied.	B

Result: 

A 

TROUBLESHOOT ECUS CONNECTED TO TERMINALS B41, B43 AND IG41 

Result: 

B 

END (REMOVE ADDITIONAL DEVICE)