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B1761

DTC B1761 indicates the Left Front Side Curtain Airbag ignition drive circuit shorted to the vehicle power supply positive (B+) — Seal 6 EV

Safety System

DTC B1761 indicates the Left Front Side Curtain Airbag ignition drive circuit shorted to the vehicle power supply positive (B+).

In the SRS system, normal airbag igniter resistance is approximately 2.0-3.0Ω.

The control module determines circuit condition by monitoring voltage and resistance.

If wiring harness insulation damage, misaligned connector terminals, or an internal airbag module fault causes the ignition circuit to contact a power wire, the control module detects an abnormally high voltage (near battery voltage).

The module immediately sets DTC B1761 and enters fail-safe mode.

This disables the Left Front Side Curtain Airbag and potentially related airbag functions, preventing deployment during a side impact and creating a severe safety hazard.

The B1761 fault code on the Seal 6 EV indicates a short to battery positive in the left front side curtain airbag ignition circuit. This is a high-severity SRS fault because it can disable that airbag and affect crash protection. Common causes include damaged wiring near the A-pillar, roof rail, or B-pillar, or a corroded/loose airbag connector. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Seal 6 EV
  • 1Harness insulation damage: Chafing, crushing, or rodent damage at the A-pillar, roof side rail, or B-pillar breaks the left front side curtain airbag harness insulation, shorting it to the body power wire.
  • 2Connector fault: Water ingress, corrosion, or terminal detachment at the airbag connector below the A-pillar (usually labeled DAB or SAB), shorting the ignition circuit terminal to the power supply terminal.
  • 3Airbag module internal short circuit: Insulation failure of the internal igniter in the side curtain airbag inflator causes a short circuit between the terminals or a short to power.
  • 4Improper accident repair: After a collision or water ingress, incorrectly securing the wiring harness or omitting clips during repair causes the harness to rub against sharp metal edges and sustain damage.
  • 5SRS control module internal fault: Component breakdown in the internal drive circuit causes a continuous high-level output, falsely detected as an external short circuit.
What To Do
  • 1
    Safety preparation: Park the vehicle on a level surface, turn off all electrical equipment, disconnect the negative battery terminal, and wait at least 90 seconds to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Fault confirmation: Use VDS2000 or a BYD dedicated diagnostic tool to read fault codes. Confirm B1761 is a current fault (Active), record freeze frame data, and check for accompanying fault codes (e.g., B1762, U0151).
  • 3
    Visual inspection: Inspect the left front curtain airbag wiring harness routing at the A-pillar trim, front roof, and B-pillar. Check for harness damage, crushing, or burn marks. Specifically inspect connector D111 (Song MAX) or D10 (Qin series) for water ingress, corrosion, or terminal back-out.
  • 4
    Circuit measurement: Disconnect the SRS control module and left front curtain airbag module connectors. Use a multimeter to measure the insulation resistance between the ignition circuit and the power supply. Normal resistance is greater than 10MΩ. Continuity or low resistance indicates a short circuit.
  • 5
    Sectional troubleshooting: Use the sectional isolation method. Disconnect the intermediate connector on the main wiring harness. Measure the circuits on the control module side and the airbag side separately to locate the short circuit. Common short-circuit points are located near the A-pillar hinge (where the door wiring harness connects to the body wiring harness).
  • 6
    Repair or replace: If the wiring harness is damaged, repair it with heat-shrink tubing or waterproof tape, then re-secure the harness to prevent interference; if the connector is damaged, replace the connector; if the airbag module has a confirmed internal short circuit, you must replace the left front side curtain airbag assembly.
  • 7
    System verification: Restore all connections, connect the battery, and turn the ignition switch ON. Use the diagnostic tool to clear the fault code. Perform the SRS system self-test (Active Test). Verify B1761 does not return and the instrument panel airbag warning light turns off.
  • 8
    Road test verification: Perform a road test simulating bumpy roads. Check if the fault code returns to confirm the repair is complete.
Real-World Cases
BYD DTC AI Analysis

Song MAX B1761 Fault After Water Wading — A-Pillar Connector Water Ingress Corrosion

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A 2019 Song MAX developed a constant airbag warning light after driving through heavy flood water. Scanning revealed DTC B1761. Inspection showed the water level had exceeded the door sills. Removing the A-pillar trim revealed significant water ingress and verdigris inside the left front side curtain airbag connector D111. The technician cleaned the connector terminals, applied conductive grease, and verified normal insulation resistance. They replaced the waterproof seal, re-secured the wiring harness, and cleared the fault. The connector seal had aged and failed during wading, causing a short circuit between terminals.
BYD DTC AI Analysis

Intermittent B1761 fault following Qin Pro accident repair — crushed wiring harness

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2020 Qin Pro intermittently set DTC B1761 after side impact collision repairs. Inspection found accident repairs had pinched the left front side curtain airbag wiring harness at the B-pillar trim clip, damaging the insulation and exposing copper wires. Harness movement while driving occasionally contacted body power lines, causing a short. Rerouted the harness to avoid the interference point, wrapped it with fleece tape, secured it, and replaced the damaged section. Fault completely resolved.
BYD DTC AI Analysis

Song Plus B1761 after panoramic sunroof modification — wiring harness pierced by screw

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A Song PLUS DM-i showed an airbag warning light after a third-party panoramic sunroof install, with the scanner reading B1761. Inspection revealed that during the modification, the installer missed the wiring clearance when tightening roof crossbeam screws, and a screw pierced the left front side curtain airbag harness, shorting the power wire to the igniter wire. The short was inside the roof rail, so the shop removed the headliner to repair the harness. They replaced the damaged section and adjusted the screw length, clearing the fault. When modifying, strictly follow the body wiring layout diagram.
BYD DTC AI Analysis

Long-term vibration caused B1761 in Qin EV — wiring harness chafing, short to power

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A 2020 Qin EV with 120,000 km set a B1761 DTC. Inspection revealed the left front side curtain airbag harness at the A-pillar hinge had suffered insulation damage from vibration due to repeated door opening and closing, with the wiring rubbing against sharp sheet metal edges. Internal conductors contacted both the A-pillar reinforcement beam (ground) and the adjacent interior light power wire simultaneously, creating a short to power. Repaired the damaged harness, fitted rubber protective sleeving and harness retaining clips, and eliminated the vibration source to resolve the fault.
Other Seal 6 EV 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.B1737DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive). The SRS ECU monitors the airbag inflator resistance via an internal current source (normal resistance: 2.0–3.0 Ω). If the ECU detects the voltage across the inflator circuit remaining close to battery voltage (>5 V and approaching 12 V) instead of the expected low potential or floating state, it identifies a short to power. This fault prevents the airbag from deploying normally during a collision because the short circuit bypasses the firing current. In extreme cases, abnormal current can cause unintended deployment, posing a severe safety hazard.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Seal 6 EV →Seal 6 EV overview →
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.