LEMON Manuals: Even more car manuals for everyone
Home >> Lexus >> 2017 >> IS 300 F Sport >> Repair and Diagnosis >> External Pages >> Different car >> Section 4 (Lighting System (Ext) - Diagnostic Codes & Circuit Tests) >> Lighting System >> DTC B2439: Headlight LH Circuit; DTC B243A: Headlight RH Circuit [09/2020 - ] >> Description

DTC B2439: Headlight LH Circuit; DTC B243A: Headlight RH Circuit [09/2020 - ]: Description

WARNING: This page does not describe the selected car, but rather 18 other vehicles, including the 2024 Lexus IS 500, 2024 Lexus IS 350, 2024 Lexus IS 300, 2023 Lexus IS 500, and 2023 Lexus IS 350. However, it is still accessible from the selected car via links, so may be relevant.

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

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

Malfunction duration: 
  1. 1 seconds or more
  • Headlight ECU sub-assembly LH
  • Headlight unit assembly LH
 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
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 
  1. 10 seconds or more
  • Headlight ECU sub-assembly RH
  • Headlight unit assembly RH
 HL AutoLeveling
scientia non olet · About LEMON Manuals