B1BA701 - Left Strut Hall Signal Abnormal

B1BA701 Deep Definition of Fault: Left Support Rod Hall Signal Abnormality

In the control architecture of the electric tailgate system, fault code B1BA701 (Left Support Rod Hall Signal Abnormality) indicates that the rear domain controller cannot receive valid physical position feedback data. The core of this fault lies in the "Hall signal", a key electrical signal used to provide real-time feedback on the physical position and rotational speed of the motor and mechanical structure. When the system detects during diagnostics that sensor output data from the left tailgate support rod exceeds expected logical ranges or is completely lost, the control unit defines this state as signal abnormality. This fault directly impacts the integrity of the electric tailgate's opening and closing functions and belongs to a typical fault definition in system communication and actuator feedback loops.

Common Fault Symptoms

Based on logical deduction of system function failure, car owners may observe the following phenomena during actual driving:

• Electric Tailgate System Partial Function Failure: The tailgate cannot complete full-travel opening or closing actions normally; it may stop halfway or lose position calibration.
• Dashboard Fault Indicator Light Illumination: The vehicle's information entertainment system or powertrain control module may display tailgate-related warning icons or text prompts on the instrument screen.
• Operation Response Delay or Error Reporting: When triggering the electric tailgate via remote buttons, remote key fob, or interior buttons, the system may return an instruction protection state of "position unknown".

Core Fault Cause Analysis

Regarding the generation mechanism of this fault code, technical diagnosis attributes the fault source to hardware or logical abnormalities in the following three dimensions:

• Hardware Components (Left Tailgate Support Rod): Internal components within the assembly carrying the Hall sensor show aging, wear, or physical damage. Failure of the sensor itself regarding its magnetic sensitivity characteristics leads to an inability to generate standard pulse signals.
• Wiring and Connectors (Physical Connection): Wires connecting the left support rod to the rear domain controller experience open circuit, short circuit, or excessive contact resistance; connector terminals become unstable due to oxidation or loosening, causing signal transmission interruption.
• Controller (Logical Operation): The signal processing module inside the rear domain controller exhibits logical deviation or calculation anomalies, failing to correctly parse received analog/digital hybrid signals, thereby determining a fault state.

Technical Monitoring & Trigger Logic

The control unit's monitoring of the left support rod Hall signal follows strict dynamic judgment logic, with specific monitoring targets as follows:

• Monitoring Targets:

  • Signal Validity: Continuously monitor the integrity of electrical signals output by the Hall sensor, identifying any open circuits or voltage drift.
  • Position Correspondence: During motor drive processes, real-time comparison of physical motion position with feedback signal consistency to ensure no signal lag or jumping occurs.

• Trigger Conditions & Judgment Logic:

  • This fault is mainly activated during the dynamic monitoring stage when driving the motor. When the system requires the tailgate to execute opening/closing actions, if characteristic values conforming to the motion curve do not appear in the Hall signal received within an allowed time window, the controller will judge it as "abnormal".
  • The system compares the expected signal range with the actual received range; once the difference exceeds a preset tolerance threshold (such as signal interruption or numerical overflow), fault code B1BA701 record is triggered.