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Low Beam Headlight Circuit: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. PERFORM ACTIVE TEST USING TECHSTREAM 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Body Electrical / Main Body / Active Test.
    5. Check that the relays operate.
      MAIN BODY

      Tester Display Test Part Control Range Diagnostic Note
      Headlight Relay Headlight relays ON/OFF -

      OK

      Headlight relays operate. (Low beam headlights illuminate.)

    NG → See step   2 

    OK → See step   7 

  2. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - AUXILIARY BATTERY AND BODY GROUND) 
    1. Disconnect the 1H No. 1 integration relay connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connector Condition Specified Condition
      1H-7 (BATT) - Body ground Always 11 to 14 V
    3. Disconnect the 1G No. 1 integration relay connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1G-22 (GND1) - Body ground Always Below 1 Ω
      1H-3 (GND2) - Body ground Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY) 
    1. Disconnect the 2C 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-9 (HL4) - 2C-32 Always Below 1 Ω
      1G-9 (HL4) - Body ground Always 10 kΩ or higher

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  4. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY 
    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.
      Fig 1: Inspecting Instrument Panel Junction Block Assembly Connector Terminals
      GTY340989Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      2C-32 - MB-15 (HRLY) Always Below 1 Ω
      2C-32 - Body ground Always 10 kΩ or higher
      TEXT IN ILLUSTRATION

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

    NG → See step   8 

    OK: Go to next step 

  5. CHECK NO. 1 INTEGRATION RELAY 
    1. Replace the No. 1 integration relay with a new or known good one. Refer to REMOVAL .
    2. Check that the low beam headlights operate normally.

      OK

      Low beam headlights operate normally.

    NG → See step   6 

    OK → END (NO. 1 INTEGRATION RELAY WAS DEFECTIVE) 

  6. REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL 
  7. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE 
  8. REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL 
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