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Home >> Lexus >> 2021 >> LS 500 Base, RWD >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Exterior Lights >> Lighting System (Ext) - Diagnostic Codes (2 Of 3) >> Lighting System >> DTC B2439-00: Headlight Source LH Malfunction; DTC B243A-00: Headlight RH Circuit [10/2023 - ] >> Description

DTC B2439-00: Headlight Source LH Malfunction; DTC B243A-00: Headlight RH Circuit [10/2023 - ]: Description

The headlight ECU sub-assembly internally boost the power supply voltage to ensure a constant supplied current for the low beam LED of their respective headlight.

By monitoring the LED power supply voltage, abnormal current and malfunctions can be detected.

DTC No. Detection Item DTC Detection Condition Trouble Area Priority
B2439-00 Headlight Source LH Malfunction Detection condition: 
  1. All of the following conditions are met:
    • Ignition switch ON
    • Low beam headlights on

Malfunction status: 
  • Headlight unit LH malfunction
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 
  1. 10 seconds or more
  • Headlight unit assembly LH
  • Headlight ECU sub-assembly LH
 A
B243A-00 Headlight RH Circuit Detection condition: 
  1. All of the following conditions are met:
    • Ignition switch ON
    • Low beam headlights on

Malfunction status: 
  • Headlight unit RH malfunction
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 
  1. 10 seconds or more
  • Headlight unit assembly RH
  • Headlight ECU sub-assembly RH
 A
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