Taillight Relay Circuit [11/2015 - 12/2018]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / Main Body / Active Test.
5. Perform the Active Test according to the display on the Techstream.

   Body Electrical > Main Body > Active Test 

   Tester Display	Measurement Item	Control Range	Diagnostic Note
   Taillight Relay	Taillight relay	ON/OFF	-

   Body Electrical > Main Body > Active Test 

   Tester Display
   Taillight Relay

   OK

   Taillight relay operates. (Taillights illuminate.)

   Result

   Proceed to
   OK
   NG

Result: 

OK 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [11/2015 - 12/2018] 

Result: 

NG 

See step  2

1. Disconnect the 3K instrument panel junction block assembly connector.
2. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   3K-1 - Body ground	Power switch off	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 instrument panel junction block assembly.

   Refer to REMOVAL [11/2015 - 12/2018]

2. Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.
3. Connect a positive (+) lead from the auxiliary battery to terminal 3K-1.
4. Connect a negative (-) lead from the auxiliary battery to terminal MB-14 (TRLY).
5. Measure the voltage according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component without harness connected (Instrument Panel Junction Block Assembly)

   -

   -

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   3F-32 - Negative (-) auxiliary battery terminal	Always	11 to 14 V
   3H-30 - Negative (-) auxiliary battery terminal	Always	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [11/2015 - 12/2018] 

Result: 

NG 

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL [11/2015 - 12/2018]