Headlight ECU RH Communication Stop Mode [06/2018 - 07/2019]: Procedure

1. Disconnect the cable from the negative (-) auxiliary battery terminal.
2. Disconnect the A12 headlight ECU sub-assembly RH connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A12-24 (CANH) - A12-23 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	54 to 69 Ω

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   Result

   Result
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (HEADLIGHT ECU SUB-ASSEMBLY RH) 

Result: 

OK 

See step  2

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A12-12 (GND) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

2. Reconnect the cable to the negative (-) auxiliary battery terminal.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A12-4 (IG) - Body ground	Power switch on (IG)	11 to 14 V

   Result

   Result
   OK
   NG

Result: 

OK 

REPLACE HEADLIGHT ECU SUB-ASSEMBLY RH. Refer to  REMOVAL [06/2018 - 09/2022] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)