Taillight Circuit [08/2017 - 08/2019]: Procedure

1. Using the Techstream, perform the Active Test.

   Refer to DATA LIST / ACTIVE TEST [08/2017 - 08/2019]

   MAIN BODY
   
   

   Tester Display	Test Part	Control Range	Diagnostic Note
   Taillight Relay	Taillight relay (TAIL)	OFF or ON	-

   OK

   Taillight relay (TAIL) operates (taillights turn on).

   Result

   Proceed to
   OK
   NG

Result: 

OK 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [08/2017 - 08/2019] 

Result: 

NG 

See step  2

1. Disconnect the cowl side junction block LH connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Cowl Side Junction Block LH)

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   3G-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  3

1. Remove the cowl side junction block LH.

   Refer to REMOVAL [08/2017 - 08/2019]

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component without harness connected (Cowl Side Junction Block LH)

   -

   -

2. Remove the main body ECU (multiplex network body ECU) from the cowl side junction block LH.

   Refer to REMOVAL [08/2017 - 08/2019]

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   3K-30 - Battery negative (-) terminal	Battery not connected to A-14 (TRLY) - 3G-1	Below 1 V
   	Battery positive (+) → 3G-1 Battery negative (-) → A-14 (TRLY)	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [08/2017 - 08/2019] 

Result: 

NG 

REPLACE COWL SIDE JUNCTION BLOCK LH. Refer to  REMOVAL [08/2017 - 08/2019]