LIGHTING SYSTEM Front Fog Light Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) controls the front fog lights via the engine room junction block assembly.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. CHECK OPERATION (TAILLIGHTS)

   
   

   1. Check the operation of the taillights.

      OK
      Taillights operate normally.

   
   

   NG

   GO TO PROBLEM SYMPTOMS TABLE Click here

   OK

2. PERFORM ACTIVE TEST USING GTS

   
   

   1. Connect the GTS to the DLC3.

   2. Turn the engine switch on (IG).

   3. Turn the GTS on.

   4. Enter the following menus: Body Electrical / Main Body / Active Test.

   5. Check that the relay operates.

      Main Body

      Tester Display	Test Part	Control Range	Diagnostic Note
      Front Fog Light Relay	Front fog light relay	ON/OFF	Light control switch is in tail position

      OK
      Front fog light relay operates. (Front fog lights come on.)

   
   

   NG

   CHECK ENGINE ROOM JUNCTION BLOCK ASSEMBLY Click here

   OK

   PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

3. CHECK ENGINE ROOM JUNCTION BLOCK ASSEMBLY

   
   

   1. Using a voltmeter, check the signal reading of the engine room junction block assembly Click here.

      OK
      Output signal reading is normal.

   
   

   NG

   INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY (RESULTS OF SIGNAL READING CHECK) Click here

   OK

4. CHECK HARNESS AND CONNECTOR (ENGINE ROOM JUNCTION BLOCK ASSEMBLY POWER SOURCE AND BODY GROUND)

   
   

   1. Remove the engine room junction block assembly from the engine room relay block and junction block assembly Click here.

      

      Text in Illustration

      *a

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

      -

      -

   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

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

5. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - ENGINE ROOM JUNCTION BLOCK ASSEMBLY)

   
   

   1. Disconnect the 3D 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 1G-2 (TAIL) - 3D-9 Always Below 1 Ω 3D-9 - Body ground Always 10 kΩ or higher 1F-13 (FOGS) - 3D-38 Always Below 1 Ω 3D-38 - Body ground Always 10 kΩ or higher

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

6. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

   
   

   1. Remove the instrument panel junction block assembly Click here.

   2. 

      Text in Illustration

      *A	for LHD
      *B	for RHD
      *a	Component without harness connected (Instrument Panel Junction Block Assembly)

      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 MB-13 (FFGO) - 3D-38 Always Below 1 Ω 3D-38 - Body ground Always 10 kΩ or higher

   4. Connect a positive (+) lead from the battery to terminal 3E-1*1 or 3F-1*2.

   5. Connect a negative (-) lead from the battery to terminal MB-14 (TRLY).

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

      Standard Voltage
      Tester Connection Condition Specified Condition 3D-9 - Body ground Always 11 to 14 V

      
      

      • *1: for LHD

      • *2: for RHD

   
   

   NG

   REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY Click here

   OK

7. CHECK ENGINE ROOM JUNCTION BLOCK ASSEMBLY

   
   

   1. Replace the engine room junction block assembly with a new or known good one Click here.

   2. Check that the fog lights operate normally.

      OK
      The fog lights operate normally.

   
   

   NG

   REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here

   OK

   END (ENGINE ROOM JUNCTION BLOCK ASSEMBLY WAS DEFECTIVE)