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Home >> Lexus >> 2019 >> LS 500 Base, AWD >> Repair and Diagnosis (Single Page) >> Brakes >> Parking Brake System >> Electric Parking Brake System - Diagnostic Codes, Circuit & Symptom Tests >> Electric Parking Brake System >> DTC U0073: Control Module Communication Bus OFF; DTC U0100: Lost Communication with ECM / PCM "A"; DTC U0124: Lost Communication with Lateral Acceleration Sensor Module; DTC U0129: Lost Communication with Brake System Control Module [12/2017 - 10/2023] >> Description
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DTC U0073: Control Module Communication Bus OFF; DTC U0100: Lost Communication with ECM / PCM "A"; DTC U0124: Lost Communication with Lateral Acceleration Sensor Module; DTC U0129: Lost Communication with Brake System Control Module [12/2017 - 10/2023]: Description

The parking brake ECU assembly communicates with the skid control ECU assembly*1, skid control ECU (brake actuator assembly)*2, deceleration sensor (yaw rate sensor) and ECM via CAN communication.

  1. *1: w/o Vacuum Brake Booster
  2. *2: w/ Vacuum Brake Booster
DTC No. Detection Item DTC Detection Condition Trouble Area Memory Note
U0073 Control Module Communication Bus OFF
  • Diagnosis Condition:

    Engine switch on (IG)

  • Malfunction Status:

    Bus OFF (cannot communicate with other ECUs)

  • Malfunction Duration:

    2 seconds (differs according to communication timing)

 CAN communication system Yes An electric parking brake system malfunction is displayed on the multi-information display.
U0100 Lost Communication with ECM / PCM "A"
  • Diagnosis Condition:

    Engine switch on (IG) and vehicle driven at 15 km/h (9 mph) or more

  • Malfunction Status:

    Parking brake ECU assembly unable to receive signals from the ECM

  • Malfunction Duration:

    Approximately 10 seconds
  • CAN communication system
  • ECM
 Yes An electric parking brake system malfunction is displayed on the multi-information display.
U0124 Lost Communication with Lateral Acceleration Sensor Module
  • Diagnosis Condition:

    Engine switch on (IG) and vehicle driven at 7 km/h (9 mph) or more

  • Malfunction Status:

    Parking brake ECU assembly unable to receive signals from the deceleration sensor (yaw rate sensor)

  • Malfunction Duration:

    Approximately 1 second
  • CAN communication system
  • Deceleration sensor (Yaw rate sensor)
 Yes An electric parking brake system malfunction is displayed on the multi-information display.
U0129 Lost Communication with Brake System Control Module
  • Diagnosis Condition:

    Engine switch on (IG)

  • Malfunction Status:

    Parking brake ECU assembly cannot receive signals from skid control ECU assembly*1

  • Malfunction Status:

    Parking brake ECU assembly cannot receive signals from skid control ECU (brake actuator assembly)*2

  • Malfunction Duration:

    Approximately 1 second or approximately 10 seconds (duration differs according to signal)
  • CAN communication system
  • Skid control ECU assembly*1
  • Skid control ECU (brake actuator assembly)*2
 Yes An electric parking brake system malfunction is displayed on the multi-information display.
  1. *1: w/o Vacuum Brake Booster
  2. *2: w/ Vacuum Brake Booster
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