Daytime Running Light Circuit [11/2020 - 12/2023]: Procedure

1. Check the operation of the low beam headlights.

   OK

   The low beam headlights operate normally.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [11/2020 - 12/2023] 

Result: 

OK 

See step  2

1. Perform the Active Test according to the display on the GTS.

   Body Electrical > Main Body > Active Test 

   Tester Display	Measurement Item	Control Range	Diagnostic Note
   Daytime Running Light	Daytime running lights	OFF or ON	-

   Body Electrical > Main Body > Active Test 

   Tester Display
   Daytime Running Light

   OK

   Daytime running lights illuminate.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [11/2020 - 12/2023] 

Result: 

NG 

See step  3

1. Disconnect the A29 headlight assembly LH connector.
2. Disconnect the A28 headlight assembly RH connector.
3. Disconnect the 4F driver side junction block assembly connector.
4. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A29-1 (B) - 4F-21	Always	Below 1 Ω
   A28-1 (B) - 4F-21	Always	Below 1 Ω
   A29-1 (B) or 4F-21 - Body ground	Always	10 kΩ or higher
   A28-1 (B) or 4F-21 - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Remove the driver side junction block assembly.

   Refer to REMOVAL [11/2020 - 11/2021] , or refer to REMOVAL [11/2021 - 12/2022] , or refer to REMOVAL [12/2022 - 12/2023]

2. Remove the main body ECU (multiplex network body ECU) from the driver side junction block assembly.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   4F-21 - A-25 (DRL)	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [11/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 12/2022]  , or refer to  REMOVAL [12/2022 - 12/2023] 

Result: 

NG 

REPLACE DRIVER SIDE JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL [11/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 12/2022]  , or refer to  REMOVAL [12/2022 - 12/2023]