B225707 - B225707 Sunshade Switch Stuck

B225707 Sunshade Switch Stuck

Fault Definition

B225707 represents a Sunshade Switch Stuck fault, this DTC mainly indicates that the vehicle internal control network has made an abnormal judgment on the feedback signal of the sunroof sunshade actuator. In the electronic electrical architecture, this fault means that the control unit (Left Domain Controller) detected that the sunshade position switch signal failed to reset or transition correctly, causing the system to be unable to accurately obtain the true state of the physical component. Technically, "Stuck" in this definition manifests as an abnormal persistent low-level logic state within a specific power supply domain, exceeding the preset normal operation window. This fault belongs to a logical operation exception in the feedback loop, reflecting persistent deviation between signal interaction links between the control unit and actuator, which may cause the system to misjudge whether the sunshade is currently closed or open.

Common Fault Symptoms

When B225707 is triggered, the vehicle sunroof control module will detect signal abnormalities and record fault history, specifically manifested in the following perceptible driving experience feedback:

• Sunshade Partial Function Failure: The system may completely prohibit sunshade lifting/lowering instructions, or cause it to stop at an unexpected position.
• Instrument Panel Warning Light On: The vehicle instrument panel may display warning icons related to the sunroof or electric systems, accompanied by fault information storage.
• Actuator Logic Conflict: When the driver operates the sunshade switch, the motor may respond slowly, fail to move, or remain stationary at an abnormal position.
• Diagnostic System Alarm: The On-Board Diagnostic (OBD) system will clearly display the B225707 fault code on a maintenance terminal, indicating that the signal level status remains locked in the low-level state.

Core Fault Cause Analysis

Based on original data and electronic control system architecture logic, potential factors leading to this DTC record can be summarized into abnormalities in the following three dimensions:

• Hardware Component Failure: The internal contacts of the sunshade switch adhere, mechanical structure jams or coil drive abnormality, causing inability to cut off the circuit under physical open/close state, continuously outputting low-level signals.
• Wiring and Connector Faults: Harness has ground short circuit phenomenon, or Connector contact resistance is too high, pin withdrawal leads to poor grounding, thereby causing signal logic state to be forcibly pulled down to erroneous level.
• Controller Logic Abnormality: Left Domain Controller internal software algorithm misjudgment or hardware circuit damage, leading to its incorrect analysis and locking of analog or digital signals from the switch, even with normal external wiring judged as stuck.

Technical Monitoring and Trigger Logic

The control unit's fault determination is based on real-time monitoring of electrical parameters within a specific power supply domain, specific trigger and record logic follows:

• Monitor System Power: This DTC is only valid when activated by Right Domain Constant Power, ensuring the monitoring circuit is in normal operating state.
• Voltage Monitoring Threshold: The system must operate under stable voltage windows, monitored signal levels must comply with the whole vehicle nominal range, accurate value range is $9V$~$16V$. Logical judgment within this voltage range excludes false alarms caused by low voltage.
• Time Trigger Condition: The control unit continuously collects logic states of switch signals. When detecting switch signal maintaining low-level state, the system starts a timer. If continuous duration $\ge 40s$, the system judges as "switch stuck", and formally records this B225707 fault code while lighting corresponding fault indicator lights.