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Home >> Lexus >> 2021 >> RX 350 Base, AWD >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Cruise Control Systems >> Dynamic Radar Cruise Control System - Diagnostic Codes & Cir Cut Tests >> Dynamic Radar Cruise Control 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 [09/2015 - 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 [09/2015 - 08/2019]: Description

The driving support ECU assembly communicates with each sensor and ECU via CAN communication.

If any malfunction is detected in a CAN communication circuit, one or more CAN communication system DTCs are stored.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL
U0100 Lost Communication with ECM / PCM "A" w/o Full-speed range following function: 
  • While the vehicle speed is 36 km/h (22 mph) or more and the dynamic radar cruise control system is operating, a communication error between the ECM and the driving support ECU assembly is detected for approximately 1 second or more.

w/ Full-speed range following function: 
  • While the vehicle speed is 5 km/h (3 mph) or more and the dynamic radar cruise control system is operating, a communication error between the ECM and the driving support ECU assembly is detected for approximately 1 second or more.
  • CAN communication system
  • ECM
  • Driving support ECU assembly
Does not come on
U0125 Lost Communication with Yaw Rate Sensor Module w/o Full-speed range following function: 
  • While the vehicle speed is 36 km/h (22 mph) or more and the dynamic radar cruise control system is operating, a communication error between the yaw rate sensor and the driving support ECU assembly is detected for approximately 1 second or more.

w/ Full-speed range following function: 
  • While the vehicle speed is 5 km/h (3 mph) or more and the dynamic radar cruise control system is operating, a communication error between the yaw rate sensor and the driving support ECU assembly is detected for approximately 1 second or more.
  • CAN communication system
  • Airbag sensor assembly (yaw rate and acceleration sensor)
  • Yaw rate sensor assembly
  • Driving support ECU assembly
Does not come on
U0126 Lost Communication with Steering Angle Sensor Module w/o Full-speed range following function: 
  • While the vehicle speed is 36 km/h (22 mph) or more and the dynamic radar cruise control system is operating, a communication error between the steering sensor and the driving support ECU assembly is detected for approximately 1 second or more.

w/ Full-speed range following function: 
  • While the vehicle speed is 5 km/h (3 mph) or more and the dynamic radar cruise control system is operating, a communication error between the steering sensor and the driving support ECU assembly is detected for approximately 1 second or more.
  • CAN communication system
  • Steering sensor
  • Driving support ECU assembly
Does not come on
U0129 Lost Communication with Brake System Control Module w/o Full-speed range following function: 
  • While the vehicle speed is 36 km/h (22 mph) or more and the dynamic radar cruise control system is operating, a communication error between the skid control ECU (brake actuator assembly) and the driving support ECU assembly is detected for approximately 2.5 seconds or more.

w/ Full-speed range following function: 
  • While the vehicle speed is 5 km/h (3 mph) or more and the dynamic radar cruise control system is operating, a communication error between the skid control ECU (brake actuator assembly) and the driving support ECU assembly is detected for approximately 2.5 seconds or more.
  • CAN communication system
  • Brake actuator assembly (skid control ECU)
  • Driving support ECU assembly
Does not come on