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Home >> Lexus >> 2021 >> LC 500 2D Coupe >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Electronically Controlled Brake System - Diagnostic Codes (Coupe) (3 Of 4) >> Electronically Controlled Brake System >> DTC C1378/44: Capacitor Communication Malfunction [03/2017 - 09/2018] >> Description

DTC C1378/44: Capacitor Communication Malfunction [03/2017 - 09/2018]: Description

The brake control power supply with bracket assembly provides auxiliary power for brake control when the battery (12 V) voltage drops.

The FAIL and ENA lines are placed between the skid control ECU assembly and the brake control power supply with bracket assembly.

Signals indicating that the brake control power supply with bracket assembly is in auxiliary mode are sent to the skid control ECU assembly through the FAIL line.

Charge permit prohibition signals are sent to the brake control power supply with bracket assembly through the ENA line.

DTC No. Detection Item INF Code DTC Detection Condition Trouble Area Note
C1378/44 Capacitor Communication Malfunction 112 Any of the following is detected
  1. Open or short in FAIL line.
  2. Malfunction inside the power back up unit.
  3. IG1 terminal voltage is 9.5 V or more, and brake control power supply with bracket assembly communication malfunction continues for 12 seconds or more.
  • Wire harness and connector
  • Improperly connected connector, deformation or corrosion of terminals
  • Brake control power supply with bracket assembly
Electronically controlled brake system DTC
DTC No. Brake warning light / yellow (minor malfunction) code ABS warning light code Slip indicator light code Brake hold standby indicator light code
C1378 44 - - -