B2CE876 - B2CE876 System Blinded

Fault Depth Definition

DTC B2CE876 (System Blind) is a critical fault code in the Adaptive Cruise Control (ACC) system, typically indicating loss of effective operational capability in the perception subsystem. In vehicle electronic control architecture, this code corresponds to the control unit's failure to determine the integrity of forward sensor data. So-called "System Blindness" refers to the inability of the control unit to acquire valid target distance or relative speed data in dynamic driving environments, leading to interruption of active safety function logic. This fault code reflects unacceptable deviations in the signal link between the millimeter-wave radar sensor and the domain controller, causing the ACC algorithm to be unable to construct an accurate surrounding traffic scene model.

Common Fault Symptoms

When the vehicle enters a driving state and triggers this fault, specific manifestations perceptible to the driver are as follows:

• ACC Function Disabled: Adaptive Cruise Control system function fails, and the corresponding ACC indicator light on the dashboard extinguishes or displays as an unavailable status.
• Speed Keep Interruption: The vehicle cannot maintain the set following distance or target speed, and the control system forcibly downgrades the longitudinal control strategy to basic cruise or off mode.
• Instrument Warning Messages: "ACC Failure" or "Radar Blind Zone" related Chinese prompt text pops up on the multifunction display or cluster.
• Functional Limitation Mode: Some advanced driver assistance system (ADAS) related functions may synchronously enter a protective disabled state along with ACC status.

Core Fault Cause Analysis

Based on diagnostic logic and hardware architecture, the main reasons for storing B2CE876 fault code can be analyzed from the following three dimensions:

• Hardware Component Failure: As the perception source, the internal transmit/receive module of the front millimeter-wave radar may degrade performance due to electronic component aging, environmental humidity effects, or physical damage, directly causing signal source failure.
• Wiring and Connector Issues: The communication harness connecting the control unit and the radar may have intermittent open circuits or short circuits, or electromagnetic shielding layers near the radar radome may be damaged, causing pulse signals transmitted to the control unit to be attenuated or interfered by noise.
• Controller Logic Operation Abnormality: The adaptive cruise controller responsible for processing radar data may have internal algorithm misjudgment, unable to parse echo data within the effective range, thereby incorrectly determining a "blind" state.

Technical Monitoring and Trigger Logic

ECU evaluates the work stability of the ACC system through specific monitoring programs, and storage of this fault code requires satisfying the following strict conditions simultaneously:

• Monitoring Target: System continuously monitors radar echo confidence and effective data coverage rate to determine if "blind" characteristics exist.
• Numerical Threshold Setting: Only when vehicle driving speed exceeds $3 \text{m/s}$ and cumulative driving distance reaches above $5 \text{km}$ does the system execute final fault confirmation logic to exclude false alarms caused by short-term signal fluctuations.
• Trigger Condition Limitation: This permanent fault code can be recorded only under Factory Mode closed status. If in diagnostic or test mode (Factory Mode), the system may only show temporary fault information and will not solidly store it to non-volatile memory, therefore this specific condition of fault judgment excludes maintenance test scenarios.