AU
B1763

DTC B1763 indicates the airbag control unit (SRS ECU) detects a 0 Ω (or near 0 Ω) resistance in the right front curtain shield airbag igniter circuit — Seal U

Safety System

DTC B1763 indicates the airbag control unit (SRS ECU) detects a 0 Ω (or near 0 Ω) resistance in the right front curtain shield airbag igniter circuit.

Normal airbag igniter resistance is 2.0-5.0 Ω.

A 0 Ω resistance indicates a short in the igniter circuit.

Possible causes include an internal igniter short, a wiring harness short to ground (GND) or power (B+), or a faulty SRS ECU internal drive circuit.

This fault causes the SRS system to enter fail-safe mode.

During a collision, the affected curtain shield airbag may fail to deploy.

The instrument panel SRS warning light illuminates continuously to indicate limited occupant protection system functionality.

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Cases Logged
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Causes
Likely Causes — Seal U
  • 1Right front side curtain airbag igniter internal short circuit: Manufacturing defects, aging, or prolonged vibration cause the igniter bridge wire inside the airbag module to break and short circuit.
  • 2Physical damage to the wiring harness: The A-pillar trim panel, headliner, or floor wiring harnesses chafe during accident repairs, modifications (e.g., routing dash cam cables), or long-term use, damaging the wire insulation and causing a short to ground or short to power.
  • 3Connector fault: Water ingress, oxidation, corrosion, or terminal deformation at the airbag wiring harness connector located inside the right front door sill trim panel or below the A-pillar, causing a short circuit between pins.
  • 4Internal SRS ECU fault: Damage to the airbag control unit internal driver chip or sampling circuit causes a false short circuit fault.
  • 5Improper repair procedures: failing to disconnect the 12V battery negative terminal as specified during previous repairs, measuring the airbag circuit directly with a multimeter resistance setting (use a dedicated airbag resistor), or electrostatic discharge causing a short circuit in the igniter.
What To Do
  • 1
    Safety preparation: Turn the vehicle OFF, disconnect the 12V battery negative terminal, and wait at least 90 seconds to fully discharge the SRS ECU backup power supply and prevent accidental airbag deployment during repair.
  • 2
    Fault confirmation and freeze frame analysis: Connect the diagnostic tool to read the freeze frame data for DTC B1763. Record environmental conditions when the fault occurred, such as vehicle speed, temperature, and voltage, to determine if the fault is intermittent or continuous.
  • 3
    Visual inspection: Remove the right A-pillar trim, headliner edge, and right front door sill trim. Inspect the curtain airbag wiring harness connector (usually a yellow plug) for looseness, water ingress, burning, or aftermarket wire taps.
  • 4
    Harness continuity test: Disconnect the SRS ECU connector and the right front curtain airbag connector. Use a multimeter to measure the resistance to ground and resistance to power at the harness-side terminals (SRS side and airbag side). The standard value must be greater than 1 MΩ. Measure harness continuity and verify no short to ground or power.
  • 5
    Airbag module isolation test: Connect a dedicated airbag substitute resistor (2.0Ω) to the circuit in place of the right front curtain airbag. Connect the negative battery terminal, clear the fault code, and power on for a self-check. If the fault code disappears, the airbag igniter has an internal short circuit; replace the right front curtain airbag assembly. If the fault code remains, the fault is in the wiring harness or ECU.
  • 6
    SRS ECU inspection: Check the ECU connector pins for corrosion or pin push-back. Measure the resistance of the corresponding ECU internal drive port. If necessary, update the SRS control unit software or replace the ECU.
  • 7
    Repair and verification: After repairing or replacing the faulty component, reconnect all connectors and install the 12V battery negative terminal. Use the diagnostic tool to clear the DTC and perform an SRS system self-check (center the steering wheel and level the vehicle). Finally, perform a road test to verify the SRS warning light turns off and no new fault codes appear.
Real-World Cases
BYD DTC AI Analysis

Song MAX right front curtain airbag short circuit after water ingress

✓
A 2019 Song MAX came in with the SRS light on after driving through heavy rain. DTC B1763 stored. Removed the right front A-pillar trim. Found the airbag circuit pins in the sill harness connector corroded from water ingress due to poor sealing, shorting the terminals (0.3Ω). Cleaned the connector with electronic contact cleaner, blew it dry, applied conductive grease, and replaced the waterproof seal. Fault cleared. Analysis: On flood-damaged vehicles, check the sealing of SRS harness connectors mounted low on the floor.
BYD DTC AI Analysis

Qin Pro modifications caused wiring harness chafing and short circuit

✓
The owner of a 2020 Qin Pro reported the SRS warning light illuminated with DTC B1763. Upon inquiry, the owner had recently installed a 360-degree camera system with wiring routed through the right-hand A-pillar. Inspection found the installer had pierced the factory SRS wiring harness insulation when securing cable clips, causing the airbag igniter wire to short to ground. Repaired damaged wiring using double-layer heat-shrink tubing, rerouted the harness to avoid sharp metal edges, cleared fault codes and restored normal operation. Note: Modifications involving the A-pillar or headliner require extra care to protect SRS wiring.
BYD DTC AI Analysis

Replaced airbag assembly due to internal short in igniter

✓
Case involves a 2019 BYD Song MAX with no accident history or modifications. After 30,000 km, the SRS warning light illuminated intermittently with DTC B1763. Disconnected the right-side roof curtain airbag connector and measured 0.1Ω across the airbag terminals (normal ~2.5Ω), indicating an internal short in the squib. Replaced the right front side curtain airbag assembly (requires headliner removal). Fault cleared. Root cause: Suspected moisture contamination of the propellant or a manufacturing defect caused the bridge wire to melt and short.
BYD DTC AI Analysis

SRS ECU false positive software fault

✓
A 2020 Qin petrol variant set a B1763 fault code. Airbag resistance and wiring harness measured normal. Consulted BYD TSB: early-batch SRS control unit software has a sampling error that triggers false short-circuit faults below 0°C. Fix: Updated SRS ECU software using VDS2000/3000 (version must be above V2.3). Fault has not returned since. Note: For short-circuit fault codes with normal measured values, suspect an ECU software bug.
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.