U01D829 - U01D829 CMRR ADAS Core System Analyzed Abnormal Data

U01D829 Fault Code Technical Documentation

Fault Depth Definition

U01D829 CMRR ADAS Core System Analysis Identifies Abnormal Data is a control strategy in Advanced Driver Assistance Systems (ADAS) involving critical sensor data processing and integration. This fault code indicates that the CMRR ADAS core system within the control unit, while executing low-level data fusion algorithms, determines that the input data stream does not meet preset physical or logical consistency standards. This fault is primarily associated with the functional integrity of the Blind Spot Monitoring System (Blind Spot Monitoring, BSM), meaning the system cannot process effective feedback information from specific perception hardware in the background. At the control strategy level, this usually reflects that the core algorithm units within the vehicle's internal communication architecture have made an untrusted determination on multi-source sensor data (such as tire size, yaw rate, tracking target data), thereby triggering safety restriction logic.

Common Fault Symptoms

When the system records and stores this fault code, drivers may observe the following instrument or functional abnormalities:

• Blind Spot Monitoring System Function Failure: The blind spot assistance warning light on the dashboard turns off or lights up a fixed fault indicator, causing no visual prompts during lane changes or reversing.
• Left Rear Corner Radar Fault Indicator: The vehicle status monitoring interface clearly shows the left rear radar sensor is offline or signal loss.
• ADAS Function Limited: Other Advanced Driver Assistance features relying on data from this area (such as Automatic Emergency Braking, Lane Change Assist) may be temporarily disabled to ensure driving safety.
• System Self-Recovery State Abnormal: During driving, relevant warning information may not clear after restarting the ignition switch and requires control logic reset.

Core Fault Cause Analysis

According to original data and diagnostic logic, the root cause of this fault can be summarized into technical factors in the following three dimensions:

• Hardware Component Failure (Sensor Side)

  • Left Rear Corner Radar Module: The specific physical radar component may have signal transmission or reception anomalies, causing it to fail to output expected reflected wave data, directly triggering left rear corner radar fault.
  • External Connection Components: Includes electromagnetic interference sources around the radar probe and detection angle errors caused by installation position offsets.

• Wiring and Connectors (Transmission Side)

  • CAN Bus Communication Quality: Although no open circuit is explicitly reported, physical layer signal integrity degradation may cause left rear corner radar sent data packet checksum errors, subsequently judged as untrusted by the core system.
  • Grounding or Power Stability: Sensor supply voltage fluctuations may affect internal ADC sampling accuracy, causing data anomalies.

• Controller Logic Operation (ECU Side)

  • DAcore Algorithm Detection Logic: The DAcore control unit continuously monitors input data quality. Once the algorithm judges tire size (tire size parameter) appears untrusted data, yawrate (yaw rate) compensation data untrusted, or regular Target Data (Tracking Target Data) is abnormal within a specific threshold, it triggers logic lock conditions.
  • Configuration Mode Interference: When the system is in an abnormal debugging state (e.g., factory mode not off), diagnostic strategy may fail, leading to false reporting of this fault code.

Technical Monitoring and Trigger Logic

The generation of this fault code is based on strict diagnostic time windows and input operating conditions, specific judgment logic as follows:

• Diagnosis Start Conditions Only when the system meets all the following prerequisite requirements will DAcore activate the monitoring process for left rear corner radar and related data streams:

  • Bus Initialization Time: Public CAN communication bus completes initialization process at least $3\text{s}$.
  • Ignition Switch Status: Start switch must be in ON position, making system enter standby mode.
  • Bus Health Status: Pub CAN not enter busoff status; or if entered busoff, must meet recovery time at least $1\text{s}$.
  • Factory Mode Limitation: Vehicle configuration Factory mode OFF, ensuring operation under normal after-sales diagnostic conditions.

• Fault Setting Conditions After system activates monitoring, if continuous monitoring detects any of the following data abnormal logic meets judgment threshold, fault code will immediately write to storage:

  • DAcore detects tire size (tire size parameter) appears untrusted data.
  • DAcore detects yawrate (yaw rate) compensation data untrusted.
  • DAcore detects general Target Data analysis results abnormal or untrusted.

  This logic aims to ensure physical plausibility of all input sensor data during vehicle dynamic driving process, preventing ADAS system from misjudging road conditions due to single sensor failure.