B1CE913 - B1CE913 Left Footwell Light Drive Circuit Open Circuit Fault

In-depth Definition of B1CE913 Left Footwell Lamp Drive Circuit Open Fault

This DTC is B1CE913 Left Footwell Lamp Drive Circuit Open, primarily belonging to the vehicle's electronic electrical architecture lighting management system. This code indicates that the vehicle's Domain Controller or its integrated functional unit in the left body control module detects an open state while monitoring the drive loop of the left footwell lamp. In system logic, the control unit outputs commands to the lamp actuator via drive signals and monitors physical feedback (such as current path continuity or load voltage response) in real-time. When monitoring results deviate from expected load characteristics, showing high impedance or no current path connection, it is determined as a drive circuit open.

Common Fault Symptoms

When DTC B1CE913 is triggered and relevant warning information is displayed, drivers and occupants typically observe the following specific phenomena:

• After opening the left footwell lamp switch, there is no light response in the left interior lighting area.
• The instrument system may record this fault code and display functional disablement or fault indicators related to "Left Footwell Lamp".
• When the vehicle enters night mode or specific driving conditions, reading lights or welcome lights on that side cannot provide necessary visual assistance.
• In some integrated diagnostic systems, abnormal linkage states of other interior lighting modules may accompany this condition.

Core Fault Cause Analysis

According to original data attribution logic, the core source of fault occurrence mainly covers hardware or circuit issues in the following three dimensions:

1. Wiring Harness or Connector Fault: Refers to damaged physical transmission links between the control unit and the lamp. This includes internal wire breaks, poor connector pin contact, corrosion or loosening of plug pieces causing signals not to return to the controller, belonging to typical line open circuits (Open Circuit).
2. Left Footwell Lamp Fault: Refers to load end execution elements failing. Internal LED array opening, driver board burning out, or bulb base damage prevents normal current flow through the load, causing the control unit to misjudge loop disconnection.
3. Left Domain Controller Fault: Refers to abnormalities in logic operation and drive output stages. Even with normal lines and bulbs, internal power transistors (Driver Output Stage) responsible for that channel output are damaged, driving logic errors, or power supply interruptions cause inability to produce effective driving voltage to light the lamp.

Technical Monitoring and Trigger Logic

The control unit's judgment of this fault is based on real-time dynamic monitoring of drive circuit electrical characteristics, specific technical logic as follows:

• Monitoring Target: System continuously collects output voltage at the left footwell lamp driver pin (Driver Pin) and loop current status. Under normal conditions, when switch activates, the drive end should output specific control voltage and establish load path; open circuit fault manifests as abnormally high voltage (no load pull-down) or detected impedance tends to infinity.
• Trigger Conditions and Numerical Ranges: Monitoring usually proceeds under dynamic conditions of drive motor (here referring to drive circuit load switching), i.e., when user operates switch to turn on left footwell lamp. System judges line status based on preset electrical thresholds, if measured loop voltage deviates from normal load voltage drop standard, and impedance detection exceeds allowable upper limit, system will trigger open circuit diagnosis logic.
• Fault Determination Specific Logic: Generation of this DTC strictly depends on real-time monitoring under "switch activated" condition, once no expected current path or voltage feedback signal matching expected state is detected during activation (e.g., expected low level becomes high with no load current), controller immediately stores fault code B1CE913 and enters protection mode.