B1C6813 - B1C6813 Right Outside Mirror Reverser Internal Resistance Open

Fault Depth Definition

DTC B1C6813 (Right Outside Mirror Commutator Internal Resistance Open Circuit) is an electrical anomaly state monitored by the vehicle electronic control unit for the right side outside mirror motor drive circuit. In this system, the adjustment function of the right outside mirror relies on a precision resistance network within the "commutator" component to provide real-time feedback of the motor's physical position and rotational speed. When the system detects that the resistance inside the commutator presents high impedance (Open Circuit) characteristics, the control unit determines it is an open circuit fault. This usually means that there has been a sudden change in the load characteristics within the motor, causing the current loop to be interrupted or signal feedback to fail, thereby disrupting the closed-loop control logic of the mirror adjustment system. The underlying logic of this fault code involves comparative monitoring of load-side resistance values and expected baseline values, belonging to the category of typical actuator electrical integrity detection.

Common Fault Symptoms

When DTC B1C6813 is recorded, the vehicle's user experience and system feedback will exhibit the following perceptible abnormal states:

• Adjustment Function Failure: When the driver issues commands by operating the outside mirror adjustment switch, the right outside mirror cannot execute movement in any direction, including horizontal, vertical, and folding actions.
• System Alerts and Warnings: Some vehicle models may display fault indicator lights or text warning messages related to the rearview mirror subsystem on the instrument cluster or vehicle display screen.
• Memory Loss of Position: Due to the motor being unable to receive or execute control signals, the vehicle may fail to maintain preset personalized mirror angle memory for the driver after getting back into the vehicle.
• Missing Operation Feedback: Pressing the adjustment switch may only provide mechanical tactile feedback without action response, indicating that while a command has been issued, the actuator has not received valid drive energy or position confirmation signals.

Core Fault Cause Analysis

According to the technical definition of this fault code, its fundamental causes can be summarized into three dimensions of system-level anomalies:

• Hardware Component Dimension: Right Outside Mirror Commutator Motor Failure. Motor internal coil burnout, oxidation of commutator contacts, or physical breakage of internal resistance components are the most direct hardware causes for open circuit. Such faults cause the motor to be unable to establish a magnetic field or maintain current flow, thus losing drive capability.
• Wiring and Connector Dimension: Harness or Connector Fault. Pins at the connector location where the right side mirror is installed may have loose connections, disconnected pins, or corrosion due to vibration; the harness from the domain controller to the commutator motor may show breakage, insulation layer damage leading to ground shorting, preventing the resistance loop from forming a complete low-impedance path.
• Controller Logic Dimension: General Domain Controller Failure. Analog front-end circuitry inside the control unit (such as ADC) may be faulty, unable to read resistance values correctly; or internal diagnostic algorithms may make logic errors during signal sampling, misjudging normal electrical fluctuations as open circuit states.

Technical Monitoring and Trigger Logic

The vehicle electronic architecture determines this fault through continuous acquisition of electrical parameters, with specific monitoring and trigger mechanisms as follows:

• Monitoring Targets: The system focuses on monitoring the current flow characteristics, load resistance value changes, and feedback signal voltage in the motor drive circuit.
• Numerical Threshold Judgment: Control unit internal algorithms compare real-time acquired impedance data with normal baseline ranges in the calibration database. When the monitored resistance value significantly deviates from the expected working interval, approaching infinity ($\infty \Omega$) state, the system determines it is an open circuit condition. Logically, this usually means there is a lack of expected current load in the loop (for example $I \approx 0A$ and no voltage drop characteristics).
• Trigger Conditions: This fault is triggered during the dynamic monitoring phase when the ignition switch is on and the rearview mirror adjustment function is activated. If the system fails to detect effective resistance feedback or motor current response within one complete adjustment instruction cycle, the control unit will confirm the abnormality after several subsequent sampling cycles, record DTC B1C6813, enter fault mode (Limp Mode), thereby cutting off drive output to the actuator to protect circuit safety.