B225813 - B225813 Sun Visor Motor Open Circuit

Fault Depth Definition

DTC B225813: Sunshade Motor Open Circuit

In the vehicle electronic electrical architecture, this fault code indicates an electrical interruption in the communication or power transmission link between the Right Domain Controller and the sunshade motor. From a system control logic perspective, an "open circuit" state means that when the control unit attempts to establish a load drive loop, it detects infinite impedance on the circuit or discontinuous physical connection. This fault code reflects the failure of real-time evaluation of actuator response capability by the power management module. When the control unit sends drive instructions to the sunshade motor and monitors feedback signals, if a closed loop cannot be formed on the electrical path, the system determines an open circuit fault. This not only means interruption of power transmission but also implies potential electrical safety hazards or possibility of internal winding damage in the actuator.

Common Fault Symptoms

When B225813 fault code is triggered during vehicle operation and the Right Domain Controller records motor open circuit conditions, users may perceive the following specific phenomena in driving experience:

• Function Loss: After operating the sunshade control switch, the sunshade completely has no action or response delay.
• Dashboard Feedback Anomaly: Dashboard may pop up relevant warning information, indicating Sunroof System or sunshade function fault.
• Silent Run Failure: When attempting to adjust sunshade position, the system may refuse to execute move instruction due to detecting no load current, causing sunshade to stay stationary.

Core Fault Cause Analysis

According to Right Domain Controller internal diagnostic logic, this fault is usually caused by hardware or physical factors in the following three dimensions:

• Hardware Component (Motor Side): Sunshade motor itself is damaged, most commonly drive coil open circuit, Hall sensor failure, or internal mechanical seizure causing abnormal current. This leads controller unable to detect normal load current signal.
• Wiring and Connectors: Wiring harness connecting Right Domain Controller and sunshade motor has physical damage, such as cable fracture, pin withdrawal, or poor contact. Connector oxidation leading to false connection also produces high impedance, simulating open circuit state, causing control unit to judge circuit interruption.
• Controller (Logic Operation): Hardware fault occurs in Right Domain Controller internal drive module, or software level logic misjudgment, leading to inability to correctly output drive signals or accurately collect current data of motor loop.

Technical Monitoring and Trigger Logic

Setting of this fault code follows strict electrical monitoring strategy, aiming to distinguish normal start-stop status from real circuit anomalies. Right Domain Controller, when attempting to control sunshade motor, will monitor current feedback in loop in real-time.

• Monitoring Target: Core monitoring object is current signal during drive period. When system is in "no current detected" state, determined as open circuit.
• Voltage Threshold Logic: Specific working conditions for fault determination are limited to dynamic process of Right Domain Controller driving sunshade motor. During this period, system must monitor current within effective working voltage range. According to diagnostic conditions, voltage environment range triggering this fault is $9V\text{~}16V$. Only when power supply voltage is in valid interval of $9V$ to $16V$, if controller detects no current flowing through output terminal, system will immediately judge open circuit fault and store DTC B225813.
• Trigger Condition: When Right Domain Controller executes drive instruction, if expected load current response cannot be detected, and system voltage maintains within $9V\text{~}16V$ range, diagnostic program confirms "no current detected", thereby formally setting fault condition and recording fault code.