Power Source Mode does not Change to ON (IG) [07/2020 - ]: Procedure

1. Using the GTS, check for certification ECU (smart key ECU assembly) DTCs.

   Body Electrical > Power Source Control > Trouble Codes 

   Body Electrical > Smart Key > Trouble Codes 

   Result

   Result	Proceed to
   DTCs are not output	A
   Smart key system (for Start Function) DTCs are output	B

Result: 

B 

GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [07/2020 - 12/2021]  , or refer to  DIAGNOSTIC TROUBLE CODE CHART [12/2021 - ] 

Result: 

A 

See step  2

1. Disconnect the A15 certification ECU (smart key ECU assembly) connector.
2. Disconnect the 4B and 4C power distribution box assembly connectors.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A15-24 (IGPD) - 4C-17	Always	Below 1 Ω
   A15-11 (IGRD) - 4B-11	Always	Below 1 Ω
   4B-36 - Body ground	Always	Below 1 Ω
   A15-24 (IGPD) or 4C-17 - Other terminals and body ground	Always	10 kΩ or higher
   A15-11 (IGRD) or 4B-11 - Other terminals and body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  3

1. Connect the A15 certification ECU (smart key ECU assembly) connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (Certification ECU (Smart Key ECU Assembly))

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A15-11 (IGRD) - Body ground	Ignition switch ACC → Ignition switch ON	1 V or less → 9 V or higher
   A15-24 (IGPD) - Body ground	Ignition switch ACC → Ignition switch ON	1 V or less → 9 V or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [07/2020 - ] 

Result: 

OK 

See step  4

1. Disconnect the A15 certification ECU (smart key ECU assembly) connector.
2. Disconnect the 4B, 4C, 4D and 4H power distribution box assembly connectors.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   4H-1 - Body ground	Ignition switch off	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  5

1. Remove the power distribution box assembly.

   Refer to REMOVAL [07/2020 - 10/2022] , or refer to REMOVAL [10/2022 - ]

2. Remove the main body ECU (multiplex network body ECU) from the power distribution box assembly.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component without harness connected (Power Distribution Box Assembly)

   -

   -

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   4C-17 - 4D-13	Always	Below 1 Ω

4. Connect the auxiliary battery terminal (+) to the 4B-11 terminal.
5. Connect the auxiliary battery terminal (-) to the 4B-36 terminal.
6. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   4H-1 - 4C-34	Battery voltage applied between terminals 4B-11 and 4B-36	Below 1 Ω
   4H-1 - 4B-38	Battery voltage applied between terminals 4B-11 and 4B-36	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE POWER DISTRIBUTION BOX ASSEMBLY. Refer to  REMOVAL [07/2020 - 10/2022]  , or refer to  REMOVAL [10/2022 - ] 

Result: 

OK 

See step  6

1. Disconnect the 4D power distribution box assembly connector.
2. Remove the IGP relay from the No. 1 engine room relay block and No. 1 junction block assembly.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   4D-13 - No. 1 engine room relay block and No. 1 junction block assembly IGP relay terminal 1	Always	Below 1 Ω
   No. 1 engine room relay block and No. 1 junction block assembly IGP relay terminal 2 - Body ground	Always	Below 1 Ω
   4D-13 or No. 1 engine room relay block and No. 1 junction block assembly IGP relay terminal 1 - Other terminals and body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  7

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   3 - 5	Battery voltage applied between terminals 1 and 2	Below 1 Ω
   	Battery voltage not applied between terminals 1 and 2	10 kΩ or higher

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *1

   IGP Relay

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

NG 

REPLACE IGP RELAY