B1C1113 - Rear Right Door Lock Motor Open Circuit

Fault Depth Definition

B1C1113 is a specific diagnostic trouble code in automotive electrical architecture for the right rear door lock actuator, primarily identified as "Right Rear Door Lock Motor Open Circuit". In the context of the Body Control Network (Body Control Network), the core meaning of this fault code refers to the control unit (Left Domain Controller) detecting a high-impedance state in the drive circuit when executing door lock instructions, meaning the current loop is interrupted. This usually means the load on the actuator side failed to form a closed electrical path, or an open circuit failure occurred in the driving MOS transistor/power stage on the controller side. This fault code directly reflects anomalies in electrical connection integrity between body and door system electronic modules, belonging to key safety monitoring data under B-CAN or LIN bus control loops.

Common Fault Symptoms

When the system determines this fault is triggered, users and vehicle management systems can typically observe the following specific manifestations:

• Right Rear Door Unlock or Locking Abnormality: The vehicle cannot normally execute safety unlock or lock instructions for the right rear door, causing the mechanical door lock to remain in an unconfirmed state.
• Body Electrical System Warning Lights On: Body-related safety indicator lights on the instrument panel may light up, alerting users that there is a potential hazard in the current door electronic system.
• Right Rear Door Lock Function Restricted: Smart keys or remote signals cannot drive the physical door lock mechanism to complete actions, potentially leading to false alarms from the anti-theft alarm system.
• Fault History Data Recording: The onboard diagnostics (OBD) system will continuously store this fault code and its related freeze frame data.

Core Fault Cause Analysis

Based on the hierarchical logic of vehicle electrical architecture, this fault is mainly caused by hardware or control anomalies in the following three dimensions:

• Hardware Components (Actuator Side): Right Rear Door Lock Fault usually points to internal motor coil breakage within the door lock actuator, severe brush wear causing poor contact, or damage to the drive module inside the door lock mechanism. When a physical disconnection occurs in the motor winding, it will be unable to consume current signals issued by the controller.
• Wiring and Connections (Transmission Medium): Harness or Connector Faults are common external factors leading to circuit open loops. This includes physical breaks in power wires/return wires from door control unit to door lock actuator, breaks caused by damaged insulation layers, as well as pin loosening or excessive contact resistance during the hinge movement of the car door.
• Controller (Logic Operation & Output): Left Domain Controller Fault involves the main control chip's ability to output drive signals. Although rare, damage to the power output stage inside the controller responsible for driving the door lock motor (such as high-side/low-side driver), resulting in inability to output control voltage, will be misjudged by the system as an external loop open.

Technical Monitoring and Trigger Logic

The generation of this fault code follows strict "Set Conditions" and "Trigger Conditions" judgment logic, monitored in real-time by the Left Domain Controller:

• Monitoring Target: The controller focuses on monitoring the current status of the control loop driving the right rear door lock motor.
• Specific Operational Requirement (Setting Fault Condition): The system enters dynamic monitoring mode only when "Right Rear Door Lock is Operating". This means the current detection logic is activated only when unlock or lock instructions are received and the controller attempts to output drive signals.
• Trigger Judgment Threshold and Logic: The core basis for system judgment is "No Current Detected in Control Loop". During a normal driving cycle (e.g., when the door motor starts), the controller should be able to measure expected load current; if the system continuously monitors near-zero or below fault threshold current during drive pulses, it confirms an open circuit state.
• Recording Mechanism: Once the above condition of missing current is met, the electronic control unit will immediately mark this event and write DTC code B1C1113 into the communication protocol to report to repair diagnostic equipment.