Power Source Circuit [08/2019 - 08/2021]: Procedure

1. Disconnect the No. 1 headlight ECU sub-assembly connectors.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *A	for No. 1 Headlight ECU Sub-assembly LH
   *B	for No. 1 Headlight ECU Sub-assembly RH
   *a	Front view of wire harness connector (to No. 1 Headlight ECU Sub-assembly)

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

   Standard Voltage

   NO. 1 HEADLIGHT ECU SUB-ASSEMBLY LH
   
   

   Tester Connection	Switch Condition	Specified Condition
   A63-13 (ECUB) - Body ground	Engine switch on (IG)	11 to 14 V

   NO. 1 HEADLIGHT ECU SUB-ASSEMBLY RH
   
   

   Tester Connection	Switch Condition	Specified Condition
   A64-13 (ECUB) - Body ground	Engine switch on (IG)	11 to 14 V

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

   Standard Resistance

   NO. 1 HEADLIGHT ECU SUB-ASSEMBLY LH
   
   

   Tester Connection	Condition	Specified Condition
   A63-12 (GND) - Body ground	Always	Below 1 Ω

   NO. 1 HEADLIGHT ECU SUB-ASSEMBLY RH
   
   

   Tester Connection	Condition	Specified Condition
   A64-12 (GND) - Body ground	Always	Below 1 Ω

   Result

   Result	Proceed to
   OK	A
   NG (No. 1 Headlight ECU Sub-assembly LH)	B
   NG (No. 1 Headlight ECU Sub-assembly RH)	C

Result: 

A 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [08/2019 - ] 

Result: 

C 

See step  7

Result: 

B 

See step  2

1. Remove the headlight relay (H-LP LH) from the No. 1 engine room relay block.
2. Inspect the headlight relay (H-LP LH).

   Refer to ON-VEHICLE INSPECTION [08/2015 - ]

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE HEADLIGHT RELAY (H-LP LH) 

Result: 

OK 

See step  3

1. Remove the headlight relay (H-LP LH) from the No. 1 engine room relay block.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Headlight Relay [H-LP LH])

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   Relay terminal 1 - Body ground	Always	11 to 14 V
   Relay terminal 5 - Body ground	Always	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Remove the headlight relay (H-LP LH) from the No. 1 engine room relay block.
2. Disconnect the A63 No. 1 headlight ECU sub-assembly LH connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   Relay terminal 3 - A63-13 (ECUB)	Always	Below 1 Ω
   Relay terminal 3 or A63-13 (ECUB) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  5

1. Remove the headlight relay (H-LP LH) from the No. 1 engine room relay block.
2. Remove the driver side junction block assembly.

   Refer to REMOVAL [08/2019 - ]

3. Remove the main body ECU (multiplex network body ECU) from the driver side junction block assembly.

   Refer to REMOVAL [08/2019 - ]

4. Connect the 5F driver side junction block assembly connector.
5. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   Relay terminal 2 - A-15 (HRLY)	Always	Below 1 Ω
   Relay terminal 2 or A-15 (HRLY) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [08/2019 - ] 

Result: 

NG 

See step  6

1. Remove the headlight relay (H-LP LH) from the No. 1 engine room relay block.
2. Disconnect the 5F driver side junction block assembly.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   Relay terminal 2 - 5F-17	Always	Below 1 Ω
   Relay terminal 2 or 5F-17 - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE DRIVER SIDE JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL [08/2019 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

1. Remove the headlight relay (H-LP RH) from the No. 1 engine room relay block.
2. Inspect the headlight light relay (H-LP RH).

   Refer to ON-VEHICLE INSPECTION [08/2015 - ]

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE HEADLIGHT RELAY (H-LP RH) 

Result: 

OK 

See step  8

1. Remove the headlight relay (H-LP RH) from the No. 1 engine room relay block.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Headlight Relay [H-LP RH])

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   Relay terminal 5 - Body ground	Always	11 to 14 V
   Relay terminal 1 - Body ground	Always	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  9

1. Remove the headlight relay (H-LP RH) from the No. 1 engine room relay block.
2. Disconnect the A64 No. 1 headlight ECU sub-assembly RH connector.
3. Disconnect the G117 main body ECU (multiplex network body ECU) connector.
4. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   Relay terminal 3 - A64-13 (ECUB)	Always	Below 1 Ω
   Relay terminal 2 - G117-1 (DIM)	Always	Below 1 Ω
   Relay terminal 3 or A64-13 (ECUB) - Body ground	Always	10 kΩ or higher
   Relay terminal 2 or G117-1 (DIM) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [08/2019 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR