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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Accessories & Equipment >> Headlights >> Lighting System (W/ AFS) - Diagnostic Codes (1 Of 2) >> LIGHTING SYSTEM (w/ AFS) >> DTC B2439-00: Headlight Source LH Malfunction; DTC B243A-00: Headlight Source RH Malfunction [11/2023 - ] >> Description

DTC B2439-00: Headlight Source LH Malfunction; DTC B243A-00: Headlight Source RH Malfunction [11/2023 - ]: Description

The headlight ECU sub-assembly LH and headlight ECU sub-assembly RH internally boost the power supply voltage to ensure a constant supplied current for the Lo/Hi 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 DTC Output from
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 assembly malfunction
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 

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

Malfunction status: 

  • Headlight assembly malfunction
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 

  1. 10 seconds or more
  • Headlight assembly RH
  • Headlight ECU sub-assembly RH
 Headlight Control (Sub)
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