B1C1313 - Trunk Lock Motor Open Circuit

B1C1313 Trunk Lock Motor Open Circuit Technical Description

### Fault Definition Depth

DTC (B1C1313) is defined as "Trunk Lock Motor Open Circuit". This fault code mainly points to execution mechanism communication and drive integrity monitoring within the rear body control domain in the vehicle electronic architecture. This diagnostic item aims to ensure that the electrical connection between the rear domain controller and its controlled electric tailgate lock assembly is functioning normally. From a system level perspective, the setting of this fault code reflects that the Control Unit (Control Unit) cannot confirm the physical continuity of the motor drive loop, indicating a high impedance or open circuit phenomenon in the control loop. In electronic control systems, an open circuit usually means a physical interruption of the current path, causing the controller to be unable to obtain expected load response through closed-loop feedback mechanism, thereby judging it as a circuit anomaly. This definition covers complete electrical path safety monitoring logic from the power output end to the actuator (motor) and then to the controller input detection end.

### Common Fault Symptoms

When the system monitors the above control loop state abnormality, car owners or drivers may perceive the fault through the following physical phenomena, specifically manifested as restrictions in vehicle interactive functions:

• Trunk Lock Failure: When attempting to open or close the trunk door, the electric actuator completely loses response and cannot complete mechanical locking action.
• Center Display Anomaly: Warning prompts or icon lighting regarding the rear lock system may pop up on the vehicle information instrument panel or central screen.
• No Feedback on Operation: When sending trunk locking/unlocking commands via key remote, physical buttons, or App control, the system outputs signals but has no actual execution action.

### Core Fault Cause Analysis

According to diagnostic logic and hardware architecture, potential causes leading to "B1C1313 Trunk Lock Motor Open Circuit" can be summarized in the following three technical dimensions:

• Hardware Component Failure:
  • Trunk Lock Actuator Failure: Internal coil burned out, brush wear or electromagnetic drive mechanism damaged, causing it to be unable to form an effective current loop.
• Wiring and Physical Connection:
  • Harness or Connector Faults: Including open circuit of power wire from motor to controller, short circuit to ground (GND) causing voltage drop, or connector pin poor contact/corrosion leading to high impedance state.
• Controller Logic Computation:
  • Rear Domain Controller Failure: Controller internal driver chip damaged, input detection circuit (ADC module) failure or logic error in calculation/judgment of current channel.

### Technical Monitoring and Trigger Logic

The system dynamically monitors the running status of the trunk lock actuator via backend program, with specific trigger judgment logic as follows:

• Monitoring Target: Control Loop Current.
  • Controller continuously monitors real-time current value flowing through motor drive loop to confirm load is connected and conducting.
• Operating Conditions (Set Fault Conditions):
  • When system enters "Trunk Lock Working" mode, specifically monitoring at the instant controller issues locking or unlocking commands.
• Trigger Criteria (Trigger Fault Conditions):
  • After command sent, if Control Unit detects control loop current below set threshold, specific judgment standard is: Detecting no current in control loop.
  • When above electrical characteristics are met (i.e., no current flowing) and continuous satisfaction of specific time or count statistic threshold, system formally records B1C1313 fault code and lights corresponding warning lamp.