AU
B1693

The BYD SRS (Supplemental Restraint System) strictly defines DTC B1693 as "Driver Airbag Circuit Resistance Low/Short to Ground", not a simple ground connection issue — Seal U

Safety System

The BYD SRS (Supplemental Restraint System) strictly defines DTC B1693 as "Driver Airbag Circuit Resistance Low/Short to Ground", not a simple ground connection issue.

This fault indicates the airbag control unit (ACU) detects the driver-side airbag (steering wheel airbag) firing circuit resistance is below the standard threshold (normal range 2.0–3.0 Ω; values below 1.5 Ω trigger this code).

Potential causes include an internal short circuit in the steering wheel clock spring flexible printed circuit, abnormal contact resistance at the airbag connector, damaged wiring harness insulation causing a short to ground, or a faulty ACU internal firing driver circuit.

This fault prevents airbag deployment during a collision (open-circuit condition) or causes unintentional deployment without a collision (short-circuit condition), representing a critical safety function failure.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Short or open circuit in the steering wheel clock spring internal FPC ribbon cable: Long-term steering wheel rotation causes fatigue damage to the flexible printed circuit inside the clock spring, resulting in abnormal circuit resistance or an intermittent short to ground.
  • 2Poor contact at the driver-side airbag connector: A loose airbag plug latch at the rear of the steering wheel, terminal oxidation, or water ingress causes resistance fluctuations or a false short circuit.
  • 3Steering column wiring harness mechanical wear: Steering wheel rotation causes the airbag wiring harness to rub against the steering column and instrument panel frame, damaging the insulation and shorting the harness to body ground.
  • 4Airbag Control Unit (ACU) poor ground or internal fault: A loose or oxidized ACU ground terminal, or a damaged internal ignition driver MOSFET, causes the resistance detection circuit to report a false fault.
  • 5Airbag inflator internal short circuit: Damaged insulation on the driver-side airbag igniter bridge wire causes the resistance to fall below the standard range.
What To Do
  • 1
    Safe power-down: Disconnect the battery negative terminal and wait at least 3 minutes for the SRS system capacitors to fully discharge to prevent accidental airbag deployment.
  • 2
    Initial visual inspection: Inspect the airbag wiring harness below the steering wheel for obvious wear or damaged insulation. Verify the airbag connector (usually yellow) fully seats and locks, and check for a broken retaining clip.
  • 3
    Static resistance measurement: Remove the steering wheel and disconnect the airbag connector. Use a multimeter to measure the airbag unit resistance (standard value: 2.0-3.0 Ω). Measure the resistance to ground at the lower end of the clock spring (ACU side) to check for a short to ground (resistance should be infinite).
  • 4
    Clock spring continuity check: Remove the steering wheel clock spring. Measure continuity in the free state and while rotating 360° in each direction to check for intermittent open or short circuits. Check the clock spring connector pins for oxidation or deformation.
  • 5
    Harness routing inspection: Inspect the harness routing from the steering wheel, through the steering column, to the ACU. Check the firewall pass-through hole, dashboard frame mounting points, and areas near the seat slide rails (if applicable) for harness chafing. Repair any damaged insulation and re-secure the harness to prevent interference.
  • 6
    Component replacement: If the clock spring is faulty, replace it with an OEM steering wheel clock spring assembly (note: some models require matching the angle position). If airbag module resistance is abnormal, or the clock spring output terminal is normal but the ACU terminal is abnormal, replace the corresponding component.
  • 7
    System configuration and reset: Reconnect all connectors and the battery. Use the VDS2000 or Launch X431 diagnostic tool to clear fault codes. Perform "SRS system configuration writing" or "ECU coding" (some models require rewriting the VIN and configuration parameters after replacing the clock spring).
  • 8
    Dynamic function verification: Start the vehicle and confirm the airbag warning lamp turns off after the self-check. Turn the steering wheel fully left and right 3 times each to simulate steering conditions and check if the fault code returns. Perform an SRS system self-diagnosis and confirm there are no current or stored fault codes.
Real-World Cases
BYD DTC AI Analysis

BYD Qin DM: Steering wheel clock spring short circuit caused airbag light to come on.

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Symptoms: Dashboard airbag warning light constantly illuminated, DTC B1693 (driver side airbag circuit resistance too low). No collision history. Diagnosis: Connected VDS scan tool and retrieved DTC B1693. Measured airbag circuit resistance at 0.8Ω (below normal 2.5-3.5Ω). Inspected steering wheel clock spring connector, found plug loose. Removed clock spring and found internal short in flat ribbon cable. Resolution: Replaced steering wheel clock spring. Reconnected and secured airbag wiring harness plug. Cleared DTC and road tested. Fault eliminated.
Original source ↗
BYD DTC AI Analysis

BYD Song Pro intermittent clock spring open circuit fault

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Symptoms: After startup, the instrument cluster displays "Check Airbag System". DTC B1693 appears intermittently, with the warning light occasionally flickering when turning the steering wheel. Diagnosis: Connected the scan tool and confirmed B1693 (Driver Side Airbag Stage 1 Circuit Short). Inspected the wiring harness beneath the steering wheel and found chafing due to frequent rotation. Checked the ACU connector and found oxidised pins. Measured continuity across the clock spring and detected an open circuit at certain steering angles. Repair: Replaced the genuine steering wheel clock spring assembly (Part No.: BYD-EG-5910). Cleaned the ACU connector pins and applied conductive grease. Adjusted the steering wheel harness routing to prevent interference.
Original source ↗
BYD DTC AI Analysis

Airbag circuit fault on BYD Tang DM after minor collision

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Symptoms: SRS warning light stays on continuously and cannot be cleared. Fault code B1693 (Driver Airbag Circuit Resistance Low) present. Vehicle had a minor front bumper impact but the airbags did not deploy. Diagnosis: Scanned with Launch X431, showing B1693. Checked the driver airbag connector and found it not fully seated. Measured airbag assembly resistance at 2.3 Ω (normal). Tested harness continuity from clock spring to ACU and found an internal short in the clock spring. Suspected that steering wheel impact during the collision caused internal damage to the clock spring. Resolution: Replaced the steering wheel clock spring. Re-secured all SRS connectors. Performed airbag configuration write using the diagnostic tool. Road tested to confirm the warning light extinguished.
Original source ↗
BYD DTC AI Analysis

Clock spring FPC fractured on BYD e5 battery electric vehicle

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Symptoms: Dashboard displayed airbag system fault, DTC B1693, occurring when starting after charging, along with intermittent steering wheel button failure. Diagnosis: Scan tool read B1693 as "driver airbag circuit short". Inspected clock spring FPC (flexible printed circuit) and found broken conductor traces. Checked ACU version – software was outdated. Measured clock spring resistance while turning the steering wheel: fluctuated between 0.5Ω and 5Ω. Solution: Replaced steering wheel clock spring with improved version (reinforced FPC). Updated airbag control unit software to latest version. Inspected and secured wiring harness cable ties to prevent strain on the harness during steering.
Original source ↗
BYD DTC AI Analysis

BYD Surui: Airbag warning light on after steering wheel removal and refitting

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Symptoms: Airbag warning light constantly on, fault code B1693. Vehicle over 5 years old, 80,000 km. Steering wheel recently removed to install multifunction buttons. Diagnosis: Used BYD diagnostic tool to confirm B1693 indicates driver side airbag circuit fault. Inspected airbag connector behind steering wheel, found connector clip broken causing poor contact. Checked clock spring, found internal ribbon cable fatigue fractured due to repeated removal and refitting. Measured airbag circuit resistance fluctuating between infinite (open circuit) and 0.2 Ω (short circuit). Solution: Replaced steering wheel clock spring assembly and airbag connector (added wiring harness retaining clip for positive contact). Re-matched airbag system by entering VIN.
Original source ↗
Other Seal U Fault Codes
B1108For the BYD Song MAX (2017–2019), DTC B1108 indicates a short circuit in the PM2.5 air quality detection module (dust sensor) or its wiring harness. The sensor uses laser scattering to detect in-cabin and outside PM2.5 concentrations and transmits data to the HVAC ECU via the LIN bus or an analog signal. Short circuit conditions include: 1) Sensor power supply wire (+5V/+12V) shorted to ground 2) Signal wire shorted to power or ground 3) Short circuit in the sensor's internal photoelectric detection circuit This fault prevents the automatic climate control from switching between fresh air and recirculation based on air quality. The system enters fail-safe mode (typically forced recirculation). Severe short-circuit current can destroy the HVAC ECU sampling circuit. The system classifies this as a Level 3 severe fault and restricts vehicle operation to prevent electrical fires or controller damage. For other BYD models (such as the Qin EV, E5, and Song DM), B1108 indicates a driver-side sunload sensor fault, reflecting differences in DTC definitions across models.B110811This DTC indicates a short circuit in the air conditioning system PM2.5 air quality sensor (rapid detector). Specifically, abnormal continuity exists between the sensor power supply circuit or signal output circuit and body ground or battery positive. This causes the control module (ACU/air conditioning controller) to detect abnormal current or a voltage signal outside the valid range (typically 0V or supply voltage). The PM2.5 sensor monitors internal and external particulate concentrations, providing the data the automatic air conditioning system uses to switch between fresh air and recirculation modes. A short circuit disables the air quality monitoring function. This fault may force the air conditioning system into recirculation protection mode and trigger related thermal management system faults, as the air conditioning system acts as a key actuator in vehicle thermal management. In severe cases, the short circuit current can damage the internal sampling circuit of the air conditioning controller or overheat the wiring harness.B1109DTC B1109 indicates an open circuit in the communication line between the air conditioning system PM2.5 air quality sensor (dust concentration sensor) and the air conditioning control unit (AC ECU), or an open circuit within the sensor internal circuitry. Typically located in the air conditioning intake duct, this sensor monitors real-time PM2.5 particle concentration inside and outside the vehicle. It provides data to the automatic air conditioning system for intelligent switching between fresh air and recirculation modes and for controlling the air purification device. During an open circuit fault, the AC ECU cannot receive the air quality signal, triggering the system fail-safe mode. Symptoms typically include failure of the automatic recirculation function, abnormal air purification indicator light operation, or abnormal air quality data displayed on the air conditioning panel. Severe cases may compromise the cabin environment control strategy, but do not directly affect vehicle driving safety.B110913DTC B110913 indicates an open signal circuit for the PM2.5 rapid detector (in-cabin air quality sensor). This sensor typically mounts inside the air conditioning system intake duct. It monitors in-cabin PM2.5 concentration in real time and provides data to the automatic air conditioning system for intelligent control of the air purification function. The BYD diagnostic protocol uses sub-code '13' to specifically indicate an open signal circuit. Although this fault theoretically affects a comfort feature, BYD Qin series vehicles classify it as a Level 3 (severe) fault. This classification occurs because the air conditioning system interacts with the battery thermal management system (e.g., monitoring battery cooling intake air quality). The fault can disable the automatic air conditioning mode and prevent the air purification function from operating. In extreme cases, it affects the battery compartment intake air quality assessment, triggering the 'repair immediately' strategy.B110AThis DTC indicates interrupted CAN bus communication or abnormal data between the air conditioning control unit (ACU) and the PM2.5 air quality sensor. The PM2.5 sensor monitors particulate concentration inside and outside the vehicle and provides the basis for purification control in the automatic air conditioning system. The ACU triggers this fault if it fails to receive a valid CAN message from the sensor within the specified period (usually 100-500 ms), if message verification fails, or if the signal frame times out. Although this fault does not affect vehicle driving safety, it disables the automatic air purification function. The air conditioning system cannot automatically switch between recirculation and fresh air modes or activate the air purification mode based on air quality. A persistent fault may restrict the thermal management strategy.
Data confidence: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.