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Home >> Lexus >> 2022 >> LS 500h RWD >> Repair and Diagnosis >> Accessories & Equipment >> Headlights >> Lighting System (Ext) - Diagnostic Codes (2 Of 2) & Circuit Tests (1 Of 2) >> Lighting System >> DTC B243D: Left Low Beam Fan Malfunction; DTC B243E: Right Low Beam Fan Malfunction [10/2017 - 10/2023] >> Description

DTC B243D: Left Low Beam Fan Malfunction; DTC B243E: Right Low Beam Fan Malfunction [10/2017 - 10/2023]: Description

The headlight ECU sub-assembly operates the low beam fan to cool the headlight LED unit in order to prevent the headlight LED unit from overheating.

Illuminates the low beam headlights and continuously operates the low beam fan.

The headlight ECU sub-assembly monitors the pulse signals from the FANP terminal when the low beam fans are operating.

HINT: 

If B243D or B243E is output, the headlight ECU sub-assembly performs low beam headlight dimming control.

DTC No. Detection Item DTC Detection Condition Trouble Area DTC Output from Note
B243D Left Low Beam Fan Malfunction Detection condition: 
  1. Power switch on (IG), low beam headlights illuminated

Malfunction status: 

  1. Fan speed signals from the low beam fan of less than 1600 rpm are continuously detected

Malfunction duration: 

  1. 120 seconds or higher
  • Headlight unit assembly LH
  • Headlight ECU sub-assembly LH
AFS -
B243E Right Low Beam Fan Malfunction Detection condition: 
  1. Power switch on (IG), low beam headlights illuminated

Malfunction status: 

  1. Fan speed signals from the low beam fan of less than 1600 rpm are continuously detected

Malfunction duration: 

  1. 120 seconds or higher
  • Headlight unit assembly RH
  • Headlight ECU sub-assembly RH
AFS (Sub) -