LIGHTING SYSTEM Low Beam Headlight Circuit

DESCRIPTION

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

WIRING DIAGRAM

1. 

   for HID Headlight:

2. 

   for Halogen Headlight:

CAUTION / NOTICE / HINT

PROCEDURE

1. Click here

   PERFORM ACTIVE TEST USING GTS

   
   

   1. Connect the GTS to the DLC3.

   2. Turn the power 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.

      Table 1. Main Body

      Tester Display	Test Part	Control Range	Diagnostic Note
      Headlight Relay	Headlight relay (Low beam headlights)	ON/OFF	-

      OK
      Headlight relay operates. (Low beam headlights illuminate.)

   
   
   • OK

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

   • NGClick here
2. Click here

   INSPECT H-LP RELAY

   
   

   1. Remove the H-LP relay from the engine room relay block and junction block assembly.

   2. 

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

      Standard Resistance
      Tester Connection Condition Specified Condition 3 - 5 Voltage not applied between terminals 1 and 2 10 kΩ or higher 3 - 5 Voltage applied between terminals 1 and 2 Below 1 Ω

   
   
   • OKClick here
   • NG

     REPLACE H-LP RELAY

3. Click here

   CHECK HARNESS AND CONNECTOR (H-LP-MAIN FUSE - H-LP RELAY)

   
   

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

      Standard Voltage
      Tester Connection Condition Specified Condition Relay terminal 2 - Body ground Always 11 to 14 V Relay terminal 5 - Body ground Always 11 to 14 V

   
   
   • OKClick here
   • NG

     REPAIR OR REPLACE HARNESS OR CONNECTOR

4. Click here

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

   
   

   1. Disconnect the A19*1 or A64*2 headlight assembly LH connector.

   2. Disconnect the A52*1 or A66*2 headlight assembly RH connector.

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

      Standard Resistance
      Table 2. *1 Tester Connection Condition Specified Condition Relay terminal 3 - A19-3 (LO) Always Below 1 Ω Relay terminal 3 - A52-3 (LO) Always Below 1 Ω Relay terminal 3 - Body ground Always 10 kΩ or higher
      Table 3. *2 Tester Connection Condition Specified Condition Relay terminal 3 - A64-2 (LO) Always Below 1 Ω Relay terminal 3 - A66-2 (LO) Always Below 1 Ω Relay terminal 3 - Body ground Always 10 kΩ or higher

      
      

      • *1: for HID Headlight

      • *2: for Halogen Headlight

   
   
   • OKClick here
   • NG

     REPAIR OR REPLACE HARNESS OR CONNECTOR

5. Click here

   CHECK HARNESS AND CONNECTOR (H-LP RELAY - INSTRUMENT PANEL 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 Relay terminal 1 - 3D-12 Always Below 1 Ω Relay terminal 1 - Body ground Always 10 kΩ or higher

   
   
   • OKClick here
   • NG

     REPAIR OR REPLACE HARNESS OR CONNECTOR

6. Click here

   INSPECT 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 3D-12 - MB-15 (HRLY) Always Below 1 Ω 3D-12 - Body ground Always 10 kΩ or higher

      Table 4. Text in Illustration

      *a	Component without harness connected (Instrument Panel Junction Block Assembly)

   
   
   • OK

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

   • NG

     REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (Click here)