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Home >> Toyota >> 2021 >> 4Runner TRD Pro >> Repair and Diagnosis (Single Page) >> Restraints >> Restraints Control Systems >> Pre-Collision System - Diagnostic Codes & Circuit Tests >> Pre-Collision System >> DTC U0100: Lost Communication with ECM / PCM "A"; DTC U0125: Lost Communication with Yaw Rate Sensor Module; DTC U0126: Lost Communication with Steering Angle Sensor Module; DTC U0129: Lost Communication with Brake System Control Module [08/2019 - ] >> Description
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DTC U0100: Lost Communication with ECM / PCM "A"; DTC U0125: Lost Communication with Yaw Rate Sensor Module; DTC U0126: Lost Communication with Steering Angle Sensor Module; DTC U0129: Lost Communication with Brake System Control Module [08/2019 - ]: Description

These DTCs are stored when a communication malfunction occurs between ECUs that perform pre-collision system control.

DTC No. Detection Item DTC Detection Condition Trouble Area
U0100 Lost Communication with ECM / PCM "A" When the vehicle is being driven at a speed of 5 km/h (4 mph) or more, a communication error between the ECM and millimeter wave radar sensor assembly is detected for approximately 4 seconds.
  • CAN communication system
  • ECM
  • Millimeter wave radar sensor assembly
U0125 Lost Communication with Yaw Rate Sensor Module When the vehicle is being driven at a speed of 5 km/h (4 mph) or more, a communication error between the yaw rate sensor (airbag sensor assembly) and millimeter wave radar sensor assembly is detected for approximately 1 second.
  • CAN communication system
  • Yaw rate sensor (Airbag sensor assembly)
  • Millimeter wave radar sensor assembly
U0126 Lost Communication with Steering Angle Sensor Module When the ignition switch is ON, a communication error between the steering angle sensor (spiral cable sub-assembly) and millimeter wave radar sensor assembly is detected for approximately 1 second.
  • CAN communication system
  • Steering angle sensor (spiral cable sub-assembly)
  • Millimeter wave radar sensor assembly
U0129 Lost Communication with Brake System Control Module When the ignition switch is ON, a communication error between the skid control ECU (master cylinder solenoid)*1 or skid control ECU (brake actuator assembly)*2 and millimeter wave radar sensor assembly is detected for approximately 3 seconds.
  • CAN communication system
  • Skid control ECU (master cylinder solenoid)*1 or skid control ECU (brake actuator assembly)*2
  • Millimeter wave radar sensor assembly
  1. *1: for Hydraulic Brake Booster
  2. *2: for Vacuum Brake Booster