B1CE513 - B1CE513 Stop Lamp Drive Circuit Open Circuit Fault

In-depth Analysis of DTC B1CE513 Brake Light Drive Circuit Open Fault

Fault Depth Definition

DTC B1CE513 is a specific Diagnostic Trouble Code (DTC) applied to R1 platform vehicles, standing for "Brake Light Drive Circuit Open Fault". This fault code is primarily monitored and managed by the Left Domain Controller, with its core function ensuring the physical execution state of the brake light signals after safety commands are issued. When the vehicle enters the "ON" gear and the system judges that brake lights need to be lit, the Left Domain Controller detects the electrical continuity at the drive end via a real-time feedback loop. If the Controller sends an ON instruction to the load side but does not detect the expected current response, the system will judge that the drive circuit has an open circuit risk. This involves not just simple lighting functions, but also concerns the integrity of the driving safety system and the physical reliability of signal transmission, covering complete electrical path monitoring from controller output to brake light loads.

Common Fault Symptoms

During actual vehicle operation, triggering the B1CE513 fault code is usually accompanied by the following phenomena perceivable by users or maintenance technicians:

• With the low beam headlights ON, when the driver presses the brake pedal and opens the brake light switch, the rear brake lights do not light up at all;
• The failure indicator lamp on the dashboard (if available) may appear lit with alarm prompts;
• When reading data streams via a diagnostic tool through the communication network of the R1 platform, normal brake light load current feedback signals may not be obtainable;
• Under specific electrical configurations (without LIN bus or integrated with LIN), the system will judge the current state as an abnormal condition of "Brake Light Not Lit".

Core Fault Cause Analysis

The technical attribution of this fault code is generally parsed into three dimensions: hardware components, line physical connections, and controller logic operations:

• Hardware Component Failure (Brake Light Failure): Internal damage occurs to the brake lamp itself, such as LED modules burned out, light units open circuits, or driver chips damaged, preventing the load from conducting current.
• Line and Connector Anomalies (Harness or Connector Fault): The harness connecting the Left Domain Controller and the rear tail light module has broken wires or insulation damage causing open circuits; or connector internal pins withdrawn, oxidized/corroded causing high contact resistance or physical breakage.
• Controller Logic Operation Abnormality (Left Domain Controller Fault): Hardware damage to power drive level inside the Left Domain Controller, or sampling circuit deviation for current monitoring at the microcontroller end, leading to inability to correctly collect load feedback signals within normal voltage ranges.

Technical Monitoring & Trigger Logic

The judgment of DTC B1CE513 relies on precise electrical parameter comparison and timing monitoring, following strict engineering thresholds:

• Monitoring Target: The system focuses primarily on drive current ($I_{drive}$) and control voltage ($V_{ctrl}$). The focus is to confirm whether the actual current value fed back to the controller deviates from expectation when the load is activated.
• Numerical Range & Conditions: The premise condition for fault judgment is that the controller supply voltage is stable between $9V \sim 16V$. Only data collected within the effective working voltage interval has diagnostic effect. If voltage exceeds this range, the system typically prioritizes judging power abnormality rather than load open circuit. In addition, triggering this fault requires a continuous monitoring duration condition: that drive current remains constant at $0$ for a continuous time of $3s$.
• Working Condition & Configuration Constraints: Monitoring is only performed in "ON" gear, and logic needs to be distinguished according to tail light architecture configuration. For vehicle configurations without LIN rear tail lights, or with LIN but brake lights integrated into the rear tail lights, the system will judge faults based on the R1 platform's diagnostic tree. The trigger moment requires an effective brake light ON instruction, but no positive response in the current channel.