Daytime Running Light Relay Circuit: Procedure

1. Check the operation of the high beam headlights.

   OK

   The high beam headlights operate normally.

NG → GO TO  PROBLEM SYMPTOMS TABLE 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / Main Body / Active Test.
5. Check that the daytime running lights illuminate.
   MAIN BODY
   
   

   Tester Display	Test Part	Control Range	Diagnostic Note
   Daytime Running Light	Daytime running lights	ON/OFF	-

   OK

   The daytime running lights illuminate.

NG → See step   3 

OK → See step   8 

1. Using a voltmeter, check the signal reading of the engine room junction block assembly. Refer to ON-VEHICLE INSPECTION .

   OK

   Output signal reading is normal.

NG → See step   9 

OK: Go to next step 

1. Remove the engine room junction block assembly from the engine room relay block and junction block assembly. Refer to REMOVAL .
   Fig 1: Checking Harness And Connector (Engine Room Junction Block Assembly Power Source And Body Ground)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A-1 (BATT) - Body ground	Always	11 to 14 V
   B-1 (ALT) - Body ground	Always	11 to 14 V

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   1F-3 (GND1) - Body ground	Always	Below 1 Ω
   1G-4 (GND2) - Body ground	Always	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   *a

   Component without engine room junction block assembly (Engine Room Relay Block and Junction Block Assembly)

   -

   -

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the 3D main body ECU (multiplex network body ECU) connector.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   1F-14 - 3D-23	Always	Below 1 Ω
   3D-23 - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the instrument panel junction block assembly. Refer to REMOVAL .
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.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   3D-23 - MB-25 (DRL)	Always	Below 1 Ω

NG → See step   10 

OK: Go to next step 

1. Replace the engine room junction block assembly with a new or a known good one. Refer to REMOVAL .
2. Check that the daytime running lights operate normally.

   OK

   The daytime running lights operate normally.

NG → See step   11 

OK → END (ENGINE ROOM JUNCTION BLOCK ASSEMBLY WAS DEFECTIVE)