B18E971 - Front Passenger Seat Fan Assembly Stall

B18E971 Fault Depth Definition

The fault code B18E971 is a critical diagnostic identifier within the Body Electronic Electrical Architecture, defined as Passenger Seat Fan Assembly Stall. This code indicates that the right domain controller (or related control unit) monitoring mechanism for the passenger-side seat ventilation system actuator has been activated. The system aims to determine if the actuator (fan motor) is in an unexpected stop, mechanical seizure, or electrical overload state by collecting drive current signals and voltage status in real-time. This logic ensures that the body electronic architecture can accurately identify abnormal physical connections when facing abnormal loads and record corresponding fault data, preventing equipment damage due to long-term operation under abnormal conditions.

Common Fault Symptoms

When the above diagnostic conditions are met and the fault code is established, drivers and passengers typically observe the following system performance and feedback:

• Passenger seat cooling function fails, unable to execute expected air circulation and cooling tasks.
• Dashboard ventilation control indicator lights may abnormally light up, flash, or turn off.
• In-vehicle Infotainment System (IVI) displays corresponding fault code records, prompting the user for maintenance.

Core Fault Cause Analysis

According to the control unit's logic determination and architecture analysis, the main reasons for recording fault code B18E971 cover the following three technical dimensions:

• Hardware Component Failure: The fan motor drive unit inside the passenger seat assembly is damaged, causing abnormal mechanical load, internal coil short circuit in the motor, or inability to rotate.
• Wiring and Connector Connection: Wiring harness has short circuits, open circuits, insulation layer damage or excessively high contact resistance; or connector loose, pin oxidation or other physical connection problems causing current loop overload.
• Controller Logic Operation: The right domain controller itself has software logic errors or hardware faults, leading to inability to correctly parse current signals or incorrect execution of control strategies.

Technical Monitoring and Trigger Logic

The determination of this fault code is based on strict threshold detection algorithms; the system records DTC only when specific conditions are met, with specific technical parameters and trigger logic as follows:

• Monitored Parameter: Real-time collection of supply voltage and feedback current waveforms for the passenger seat ventilation system.
• System Active State: The vehicle must be in ON position power state, and the passenger seat ventilation function must be actively working.
• Fault Determination Value Range: System detects supply voltage stable within effective operating range of $9V$~$16V$; simultaneously, drive current threshold is set to $> 10A$.
• Fault Duration Logic: Control unit needs continuous acquisition of drive current exceeding $10A$ lasting for $3s$ (note: time, current parameters are configurable). Only when controller enters active control mode and voltage satisfies conditions will the above threshold exceedance trigger fault determination.