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Home >> Lexus >> 2016 >> RX 350 Base, AWD >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Exterior Lights >> Lighting System (W/ Automatic Headlight Beam Level Control System) - Diagnostic Codes >> LIGHTING SYSTEM (w/ Automatic Headlight Beam Level Control System) >> DTC B2439: Headlight LH Circuit; DTC B243A: Headlight RH Circuit [08/2019 - ] >> Description
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DTC B2439: Headlight LH Circuit; DTC B243A: Headlight RH Circuit [08/2019 - ]: Description

The No. 1 headlight ECU sub-assembly LH and No. 1 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 MULTIPLE BEAM HEADLIGHT

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 malfunction
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 
  1. 1 seconds or more
  • No. 1 headlight ECU sub-assembly LH
  • Headlight unit LH
 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 malfunction
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 
  1. 10 seconds or more
  • No. 1 headlight ECU sub-assembly RH
  • Headlight unit RH
 AFS
FOR SINGLE BEAM HEADLIGHT

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 malfunction
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 
  1. 1 seconds or more
  • No. 1 headlight ECU sub-assembly LH
  • Headlight unit LH
 HL Auto Leveling
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 malfunction
  • Open/short in Lo/Hi beam circuit

Malfunction duration: 
  1. 10 seconds or more
  • No. 1 headlight ECU sub-assembly RH
  • Headlight unit RH
 HL Auto Leveling
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