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Home >> Lexus >> 2020 >> ES 300h Luxury >> Repair and Diagnosis >> External Pages >> Different car >> Section 166 (Lighting System (Ext) (Except Hybrid) - Diagnostic Codes (2 Of 2) & Symptom Tests) >> LIGHTING SYSTEM (for Gasoline Model) >> DTC B2439: Headlight LH Circuit; DTC B243A: Headlight RH Circuit [06/2018 - 08/2021] >> Description

DTC B2439: Headlight LH Circuit; DTC B243A: Headlight RH Circuit [06/2018 - 08/2021]: Description

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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.

FOR LED TYPE TURN SIGNAL LIGHT

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:
    • Engine switch on (IG)
    • Low beam headlights on

Malfunction status: 
  • Headlight unit assembly malfunction (for TMC Made)
  • Headlight assembly malfunction (for TMMK Made)
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 
  1. 10 seconds or more
  • Headlight ECU sub-assembly LH
  • Headlight unit assembly LH (for TMC Made)
  • Headlight assembly LH (for TMMK Made)
 AFS
B243A Headlight RH Circuit Detection condition: 
  1. All of the following conditions are met:
    • Engine switch on (IG)
    • Low beam headlights on

Malfunction status: 
  • Headlight unit assembly malfunction (for TMC Made)
  • Headlight assembly malfunction (for TMMK Made)
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 
  1. 10 seconds or more
  • Headlight ECU sub-assembly RH
  • Headlight unit assembly RH (for TMC Made)
  • Headlight assembly RH (for TMMK Made)
 AFS (Sub)
FOR BULB TYPE TURN SIGNAL LIGHT

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:
    • Engine switch on (IG)
    • Low beam headlights on

Malfunction status: 
  • Headlight unit assembly malfunction (for TMC Made)
  • Headlight assembly malfunction (for TMMK Made)
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 
  1. 10 seconds or more
  • Headlight ECU sub-assembly LH
  • Headlight unit assembly LH (for TMC Made)
  • Headlight assembly LH (for TMMK Made)
 HL AutoLeveling
B243A Headlight RH Circuit Detection condition: 
  1. All of the following conditions are met:
    • Engine switch on (IG)
    • Low beam headlights on

Malfunction status: 
  • Headlight unit assembly malfunction (for TMC Made)
  • Headlight assembly malfunction (for TMMK Made)
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 
  1. 10 seconds or more
  • Headlight ECU sub-assembly RH
  • Headlight unit assembly RH (for TMC Made)
  • Headlight assembly RH (for TMMK Made)
 HL AutoLeveling (Sub)
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