B1CDA13 - B1CDA13 Trunk Lighting Lamp Driver Circuit Open Circuit

B1CDA13 Detailed Fault Definition

Fault code B1CDA13 is defined in the vehicle network communication system as "Trunk Lighting Driver Circuit Open". This code identifies a high impedance or non-conductive state in the physical connection or electrical link between the Left Domain Controller and downstream actuators. In this control architecture, the Left Domain Controller is responsible for managing body comfort and functional loads output, while trunk lighting acts as a controlled load; its drive circuit continuity is a key indicator monitored by the system. When an open circuit is detected on the drive signal path, the system determines B1CDA13, indicating that the load cannot receive electrical energy through the predetermined current path, resulting in fail-safe operation for that function.

Common Fault Symptoms

When vehicle ECU (Electronic Control Unit) records and sets this fault code, user-perceivable driving experience and dashboard feedback typically manifest as:

• Function Failure: After opening trunk lid, lighting that should turn on does not light up, or brightness is significantly insufficient.
• System Prompt: Some models display body electrical system related warning icons in Driver Information Center or Instrument Cluster, indicating door/trunk circuit abnormality.
• Environmental Perception Impact: In dark parking environments, inability to obtain necessary local illumination when trunk opens may affect user item retrieval and safety.
• Logic State Lock: Vehicle control system may enter "Fail-Safe Mode", no longer attempting to control that load to protect the circuit from further damage.

Core Fault Cause Analysis

Based on electrical characteristics of system architecture and feedback loop principles, the root causes are mainly classified into the following three dimensions:

1. Hardware Component Failure (Actuator Side)

   • Physical damage to internal components of the trunk lighting itself (e.g., LED array, integrated driver or power module) causing an internal open circuit.
   • Bulb filament burns out or LED array fails, causing infinite impedance on the load side.

2. Wiring and Connector Failure (Connection Side)

   • Wire insulation damage and conductor break in the harness due to wear, fracture or external pull force.
   • Poor pin contact, oxidation corrosion or improper insertion of the connector, preventing control signal transmission to the load side.
   • Deformation of internal contact spring of the connector causing physical interruption of circuit connectivity.

3. Controller Failure (Logic and Drive Side)

   • Damage to power stage output circuit inside Left Domain Controller, unable to supply power normally to lighting.
   • Sampling circuit for current or voltage in controller shows offset, leading system misjudgement as open circuit.
   • Internal protection logic triggered inside controller, forcibly cutting off the output channel to that load.

Technical Monitoring and Trigger Logic

The setting of fault code B1CDA13 is based on the Left Domain Controller's bottom-level diagnostic algorithm; its monitoring process follows strict electrical characteristic comparison logic:

• Monitoring Target: System real-time monitors current flow in drive circuit and node voltage drop, focusing on zero current phenomena under instruction activation state.
• Trigger Conditions:
  • Configuration Requirement: The vehicle must have "Trunk Lighting Configuration" enabled; otherwise this logic remains inactive.
  • Load State: When the system receives an open command, and confirms that a "Trunk Lighting On" enable signal has been issued.
• Electrical Threshold Judgment:
  • The basic environment requirement for fault judgment is controller voltage between $9V$~$16V$. Within this working voltage interval, if the controller detects drive circuit open characteristics (e.g., missing current feedback or abnormal load side voltage), the condition is satisfied immediately.
  • Once detecting that the drive circuit cannot conduct even with instruction issued and normal power supply, control unit determines "Drive Circuit Open Detected", then records fault code B1CDA13 and stores fault counter.