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Home >> Toyota >> 2013 >> Prius Plug-in >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 129 (Lighting System (Diagnostic Codes & Circuit Tests) (Except Plug-In)) >> Lighting System >> Circuit Tests >> Headlight Signal Circuit >> Procedure
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Headlight Signal Circuit: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. READ VALUE 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 / HL Auto Leveling / Data List.
    5. Read the display on the Techstream.
      HL AUTO LEVELING

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Lo Beam St Low beam headlight state/ON or OFF ON: Low beam headlights on
      OFF: Low beam headlights off
      -

      OK

      Normal conditions listed above are displayed.

    NG → See step   2 

    OK → See step   3 

  2. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - ECU) 
    1. Disconnect the A48 headlight leveling ECU assembly connector.
      Fig 1: Identifying Headlight Leveling ECU Assembly Connector Terminals
      GTY221503Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A48-3 (HDLP) - Body ground Light control switch in head position 11 to 14 V
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Headlight Leveling ECU Assembly)

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → See step   4 

  3. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE 
  4. REPLACE HEADLIGHT LEVELING ECU ASSEMBLY. Refer to  REMOVAL