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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Accessories & Equipment >> Exterior Lights >> Lighting System (W/ AFS) - Diagnostic Codes (1 Of 2) >> LIGHTING SYSTEM (w/ AFS) >> DTC B2439: Headlight LH Circuit; DTC B243A: Headlight RH Circuit [12/2019 - 11/2023] >> Description

DTC B2439: Headlight LH Circuit; DTC B243A: Headlight RH Circuit [12/2019 - 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 Headlight LH Circuit 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 ECU sub-assembly LH
  • Headlight assembly LH
 AFS
B243A Headlight RH Circuit 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 ECU sub-assembly RH
  • Headlight assembly RH
 AFS (Sub)
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