Low Beam Headlight Circuit [11/2015 - 07/2020]: 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
   Headlight Relay	Headlight relay (low beam headlights)	ON/OFF	-

   Body Electrical > Main Body > Active Test 

   Tester Display
   Headlight Relay

   OK

   Headlight relay operates. (Low beam headlights 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]  , or refer to  PROBLEM SYMPTOMS TABLE [12/2018 -] 

Result: 

NG 

See step  2

1. Remove the No. 1 integration relay from the No. 1 engine room relay block and No. 1 junction block assembly.

   Refer to REMOVAL [11/2015 - 12/2018] , or refer to REMOVAL [12/2018 - 07/2020]

2. Inspect the No. 1 integration relay.

   Refer to INSPECTION [11/2015 -]

   OK

   No. 1 integration relay is normal.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE NO. 1 INTEGRATION RELAY. Refer to  REMOVAL [11/2015 - 12/2018]  , or refer to  REMOVAL [12/2018 - 07/2020] 

Result: 

OK 

See step  3

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   1A-5 - Body ground	Power switch off	11 to 14 V
   1B-8 - 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  4

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   1B-2 - 3F-31	Always	Below 1 Ω
   1B-2 or 3F-31 - Body ground	Always	10 kΩ or higher
   1A-11 - 3F-31	Always	Below 1 Ω
   1A-11 or 3F-31 - 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 instrument panel junction block assembly.

   Refer to REMOVAL [11/2015 - 12/2018] , or refer to REMOVAL [12/2018 - 07/2020]

2. Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.
3. Measure the resistance 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 Resistance

   Tester Connection	Condition	Specified Condition
   3F-31 - MB-15 (HRLY)	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [11/2015 - 12/2018]  , or refer to  REMOVAL [12/2018 - 07/2020] 

Result: 

NG 

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL [11/2015 - 12/2018]  , or refer to  REMOVAL [12/2018 - 07/2020]