B18E913 - B18E913 B18E913 Passenger Seat Fan Assembly Open Circuit

meaning of this DTC is "Passenger Seat Fan Assembly Open Circuit", indicating that the control system detected an open circuit condition or abnormal impedance in the drive side fan motor circuit, causing current to fail flowing through the load end. In the vehicle's electronic electrical architecture, this code reflects a failure of the domain controller to validate feedback signals from the actuator (fan motor). When the control unit issues a drive command, the expected drive port current is not recognized in closed-loop feedback, and the system determines physical connection interruption or internal coil failure, thereby marking this DTC to record vehicle diagnostic data.

Common Fault Symptoms

When B18E913 fault code illuminates or is stored, actual driving performance observable by users typically includes the following characteristics:

• Ventilation Function Completely Lost: No air flows out of the ventilation outlet below the passenger seat, even when the control system is turned on.
• System Feedback Abnormality: The dashboard or center screen may display warning icons related to seat ventilation or prompt text such as "Please check passenger seat".
• Relay Actuation Sound May Be Missing: When attempting to turn on the ventilation function, the action sound of the drive relay cannot be heard, indicating that no effective load was obtained at the output end.
• Intermittent Response Failure: Under specific operating conditions (e.g., after severe vibration), if there is poor contact in connectors, functional interruption may occur suddenly.

Core Fault Cause Analysis

From the perspective of the vehicle electronic system architecture, triggering B18E913 is usually caused by hardware or logic factors in the following three dimensions:

• Hardware Component Internal Failure (Passenger Seat Assembly): The motor coil inside the fan assembly physically burns out, opens circuit, or the solenoid actuation mechanism sticks. This is the most direct reason for no current feedback at the drive port and belongs to damage at the actuator end.
• Wiring and Connector Fault: Wires connecting between the Right Zone Controller and the passenger seat harness have an open circuit; or connector pins in the wire harness terminal are retracted, oxidized/corroded leading to physical contact not conducting, causing signal transmission path interruption.
• Controller Logic Output Abnormality (Right Zone Controller): The power stage circuit driving the port (such as internal MOSFET tube or relay coil) is damaged and cannot supply power to the load; or the current monitoring sampling resistor inside the control chip opens circuit, leading to misjudgment of external open circuit.

Technical Monitoring & Trigger Logic

The Right Zone Controller's determination of passenger seat fan assembly open circuit fault follows a strict dynamic monitoring strategy, its trigger logic must simultaneously meet the following voltage, operating condition and time threshold conditions:

1. Supply Voltage Range: System only enables monitoring when it detects drive port voltage within normal supply interval of $9V \sim 16V$. Below this range is usually determined as battery or supply fault, not pure load open circuit.
2. Function Status Requirement: Prerequisite for trigger determination is driver has operated to "ON" position (ignition switch open or system ready), and passenger seat ventilation is in working state (i.e., controller has output drive command). If system not activated ventilation mode, current 0 is normal logic, no error reported.
3. Current Feedback Threshold: Core criterion is current value monitored for continuous time. Control system sets threshold judgment standard as collecting drive port current equals $0$ (current value zero or near-zero minimal signal).
4. Duration Parameter: Controller internal timer needs to detect above current condition satisfied continuously for $3s$. Note: This time threshold parameter is configurable in lower-level calibration to adapt to different vehicle models' high requirements for dynamic stability. Only when the above voltage interval, function mode and current time base features all hold, diagnostic algorithm finally establishes B18E913 fault code and lights up indicator light.

Cause Analysis From the perspective of the vehicle electronic system architecture, triggering B18E913 is usually caused by hardware or logic factors in the following three dimensions:

• Hardware Component Internal Failure (Passenger Seat Assembly): The motor coil inside the fan assembly physically burns out, opens circuit, or the solenoid actuation mechanism sticks. This is the most direct reason for no current feedback at the drive port and belongs to damage at the actuator end.
• Wiring and Connector Fault: Wires connecting between the Right Zone Controller and the passenger seat harness have an open circuit; or connector pins in the wire harness terminal are retracted, oxidized/corroded leading to physical contact not conducting, causing signal transmission path interruption.
• Controller Logic Output Abnormality (Right Zone Controller): The power stage circuit driving the port (such as internal MOSFET tube or relay coil) is damaged and cannot supply power to the load; or the current monitoring sampling resistor inside the control chip opens circuit, leading to misjudgment of external open circuit.

Technical Monitoring & Trigger Logic

The Right Zone Controller's determination of passenger seat fan assembly open circuit fault follows a strict dynamic monitoring strategy, its trigger logic must simultaneously meet the following voltage, operating condition and time threshold conditions:

1. Supply Voltage Range: System only enables monitoring when it detects drive port voltage within normal supply interval of $9V \sim 16V$. Below this range is usually determined as battery or supply fault, not pure load open circuit.
2. Function Status Requirement: Prerequisite for trigger determination is driver has operated to "ON" position (ignition switch open or system ready), and passenger seat ventilation is in working state (i.e., controller has output drive command). If system not activated ventilation mode, current 0 is normal logic, no error reported.
3. Current Feedback Threshold: Core criterion is current value monitored for continuous time. Control system sets threshold judgment standard as collecting drive port current equals $0$ (current value zero or near-zero minimal signal).
4. Duration Parameter: Controller internal timer needs to detect above current condition satisfied continuously for $3s$. Note: This time threshold parameter is configurable in lower-level calibration to adapt to different vehicle models' high requirements for dynamic stability. Only when the above voltage interval, function mode and current time base features all hold, diagnostic algorithm finally establishes B18E913 fault code and lights up indicator light.