Headlight ECU Communication Stop Mode [09/2017 - 05/2019]: Procedure

1. Disconnect the cable from the negative (-) auxiliary battery terminal.
2. Disconnect the headlight ECU sub-assembly LH connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Headlight ECU Sub-assembly LH)

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A19-24 (CANH) - A19-23 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	54 to 69 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR 

Result: 

OK 

See step  2

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

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Headlight ECU Sub-assembly LH)

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A19-12 (GND) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω

2. Reconnect the cable to the negative (-) auxiliary battery terminal.
   NOTE:

   When disconnecting the cable, some systems need to be initialized after the cable is reconnected.

   Refer to INITIALIZATION [09/2017 - 05/2019]

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

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   A19-4 (IG) - Body ground	Power switch on (IG)	11 to 14 V
   	Power switch off	Below 1 V
   A19-13 (ECUB) - Body ground	Power switch on (IG)	11 to 14 V
   	Power switch off	Below 1 V

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE HEADLIGHT ECU SUB-ASSEMBLY LH. Refer to  REMOVAL [09/2017 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)