LIGHTING SYSTEM(w/o Automatic Headlight Beam Level Control System) LO-beam Headlight does not Illuminate

DESCRIPTION

The main body ECU (multiplex network body ECU) controls the low beam headlights.

WIRING DIAGRAM

1. HEADLIGHT ASSEMBLY CIRCUIT

   

CAUTION / NOTICE / HINT

PROCEDURE

1. PERFORM ACTIVE TEST USING GTS

   
   

   1. Connect the GTS to the DLC3.

   2. Turn the ignition switch to ON.

   3. Turn the GTS on.

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

   5. 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
      Headlight Relay	Low beam headlights	OFF or ON	-

      
      Body Electrical > Main Body > Active Test

      Tester Display
      Headlight Relay

      OK
      Low beam headlights illuminate.

      Result
      Result Proceed to OK A NG (for LH Side) B NG (for RH Side) C

   
   

   A

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

   C

   INSPECT HEADLIGHT ASSEMBLY RH (LO TERMINAL VOLTAGE) Click here

   B

2. INSPECT HEADLIGHT ASSEMBLY LH (LO TERMINAL VOLTAGE)

   

   *a	Front view of wire harness connector (to Headlight Assembly LH)

   
   

   1. Disconnect the A74 headlight assembly LH connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition A74-3 (LO) - Body ground Light control switch in head position 11 to 14 V

      Result
      Proceed to OK NG

   
   

   NG

   CHECK HARNESS AND CONNECTOR (H-LP LH RELAY - HEADLIGHT ASSEMBLY LH) Click here

   OK

3. CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY LH - BODY GROUND)

   
   

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

      Standard Resistance
      Tester Connection Condition Specified Condition A74-1 (E) - Body ground Always Below 1 Ω

      Result
      Proceed to OK NG

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

4. INSPECT HEADLIGHT UNIT ASSEMBLY LH

   

   *a	Component without harness connected (to Wire Harness)	*b	Component without harness connected (to Light Control ECU)
   *c	Component without harness connected (to Headlight LED Unit Assembly LH)	-	-

   
   

   1. Remove the headlight assembly LH.

      Click here

   2. Remove the headlight unit assembly LH.

      Click here

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

      Standard Resistance
      Tester Connection Condition Specified Condition A74-1 (E) - B-6 Always Below 1 Ω A74-3 (LO) - B-7 Always Below 1 Ω B-4 - D-1 Always Below 1 Ω B-10 - D-2 Always Below 1 Ω

      Result
      Proceed to OK NG

   
   

   NG

   REPLACE HEADLIGHT UNIT ASSEMBLY LH Click here

   OK

5. CHECK LIGHT CONTROL ECU

   
   

   1. Remove each light control ECU, interchange the light control ECU (for LH) with (for RH) and connect the connectors.

      Click here

      Result
      Proceed to NEXT

   
   

   NEXT

6. CHECK OPERATION (LOW BEAM HEADLIGHT)

   
   

   1. Check that the low beam headlight operates normally.

      OK
      Low beam headlight operates normally.

      Result
      Proceed to OK NG

   
   

   OK

   REPLACE HEADLIGHT LED UNIT ASSEMBLY LH Click here

   NG

   REPLACE LIGHT CONTROL ECU Click here

7. CHECK HARNESS AND CONNECTOR (H-LP LH RELAY - HEADLIGHT ASSEMBLY LH)

   
   

   1. Remove the H-LP LH relay.

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

      Standard Resistance
      Tester Connection Condition Specified Condition 3 (H-LP LH relay) - A74-3 (LO) Always Below 1 Ω 3 (H-LP LH relay) or A74-3 (LO) - Body ground Always 10 kΩ or higher

      Result
      Proceed to OK NG

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

8. INSPECT H-LP LH RELAY

   
   

   1. Inspect the H-LP LH relay.

      Click here

      Result
      Proceed to OK NG

   
   

   NG

   REPLACE H-LP LH RELAY

   OK

9. CHECK HARNESS AND CONNECTOR (POWER SOURCE - H-LP LH RELAY)

   
   

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

      Standard Voltage
      Tester Connection Condition Specified Condition 2 (H-LP LH relay) - Body ground Always 11 to 14 V 5 (H-LP LH relay) - Body ground Always 11 to 14 V

      Result
      Proceed to OK NG

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

10. CHECK HARNESS AND CONNECTOR (H-LP LH RELAY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

    
    

    1. Disconnect the 3C 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 1 (H-LP LH relay) - 3C-31 Always Below 1 Ω 1 (H-LP LH relay) or 3C-31 - Body ground Always 10 kΩ or higher

       Result
       Proceed to OK NG

    
    

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

11. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

    

    *a

    Component without harness connected (Instrument Panel Junction Block Assembly)

    -

    -

    
    

    1. Remove the instrument panel junction block assembly.

       Click here

    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 3C-31 - MB-15 (HRLY) Always Below 1 Ω

       Result
       Proceed to OK NG

    
    

    OK

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

    NG

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY Click here

12. INSPECT HEADLIGHT ASSEMBLY RH (LO TERMINAL VOLTAGE)

    

    *a	Front view of wire harness connector (to Headlight Assembly RH)

    
    

    1. Disconnect the A73 headlight assembly RH connector.

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

       Standard Voltage
       Tester Connection Condition Specified Condition A73-3 (LO) - Body ground Light control switch in head position 11 to 14 V

       Result
       Proceed to OK NG

    
    

    NG

    CHECK HARNESS AND CONNECTOR (H-LP RH RELAY - HEADLIGHT ASSEMBLY RH) Click here

    OK

13. CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY RH - BODY GROUND)

    
    

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

       Standard Resistance
       Tester Connection Condition Specified Condition A73-1 (E) - Body ground Always Below 1 Ω

       Result
       Proceed to OK NG

    
    

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

14. INSPECT HEADLIGHT UNIT ASSEMBLY RH

    

    *a	Component without harness connected (to Wire Harness)	*b	Component without harness connected (to Light Control ECU)
    *c	Component without harness connected (to Headlight LED Unit Assembly RH)	-	-

    
    

    1. Remove the headlight assembly RH.

       Click here

    2. Remove the headlight unit assembly RH.

       Click here

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

       Standard Resistance
       Tester Connection Condition Specified Condition A73-1 (E) - B-6 Always Below 1 Ω A73-3 (LO) - B-7 Always Below 1 Ω B-4 - D-1 Always Below 1 Ω B-10 - D-2 Always Below 1 Ω

       Result
       Proceed to OK NG

    
    

    NG

    REPLACE HEADLIGHT UNIT ASSEMBLY RH Click here

    OK

15. CHECK LIGHT CONTROL ECU

    
    

    1. Remove each light control ECU, interchange the light control ECU (for RH) with (for LH) and connect the connectors.

       Click here

       Result
       Proceed to NEXT

    
    

    NEXT

16. CHECK OPERATION (LOW BEAM HEADLIGHT)

    
    

    1. Check that the low beam headlight operates normally.

       OK
       Low beam headlight operates normally.

       Result
       Proceed to OK NG

    
    

    OK

    REPLACE HEADLIGHT LED UNIT ASSEMBLY RH Click here

    NG

    REPLACE LIGHT CONTROL ECU Click here

17. CHECK HARNESS AND CONNECTOR (H-LP RH RELAY - HEADLIGHT ASSEMBLY RH)

    
    

    1. Remove the H-LP RH relay.

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

       Standard Resistance
       Tester Connection Condition Specified Condition 3 (H-LP RH relay) - A73-3 (LO) Always Below 1 Ω 3 (H-LP RH relay) or A73-3 (LO) - Body ground Always 10 kΩ or higher

       Result
       Proceed to OK NG

    
    

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

18. INSPECT H-LP RH RELAY

    
    

    1. Inspect the H-LP RH relay.

       Click here

       Result
       Proceed to OK NG

    
    

    NG

    REPLACE H-LP RH RELAY

    OK

19. CHECK HARNESS AND CONNECTOR (POWER SOURCE - H-LP RH RELAY)

    
    

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

       Standard Voltage
       Tester Connection Condition Specified Condition 2 (H-LP RH relay) - Body ground Always 11 to 14 V 5 (H-LP RH relay) - Body ground Always 11 to 14 V

       Result
       Proceed to OK NG

    
    

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

20. CHECK HARNESS AND CONNECTOR (H-LP RH RELAY - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU))

    
    

    1. Disconnect the K52 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 1 (H-LP RH relay) - K52-12 (HRY2) Always Below 1 Ω 1 (H-LP RH relay) or K52-12 (HRY2) - Body ground Always 10 kΩ or higher

       Result
       Proceed to OK NG

    
    

    OK

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

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR