AU
B1762

DTC B1762 indicates the SRS (Supplemental Restraint System) detected a short to ground in the Left Front Side Curtain Airbag deployment circuit — Seal U

Safety System

DTC B1762 indicates the SRS (Supplemental Restraint System) detected a short to ground in the Left Front Side Curtain Airbag deployment circuit.

Electrically, the side curtain airbag squib is a resistive load (typically 2-5 Ω).

The SRS ECU controls it via a twisted pair.

The ECU sets this code when it detects the circuit's insulation resistance to body ground falls below the threshold (typically <1 Ω) or when it detects abnormal ground voltage.

This fault indicates: 1) Positive or negative squib wiring shorted to body metal within the A-pillar, B-pillar, or C-pillar trim, or in the headliner harness; 2) Igniter bridge wire insulation failure inside the airbag module; 3) Driver MOSFET breakdown inside the SRS ECU.

This fault prevents the airbag from deploying during a collision (open-circuit protection mode) or, in extreme cases, creates a risk of unintended deployment.

Consequently, the ECU illuminates the airbag warning light and disables the system.

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Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Wiring harness abrasion inside the sill trim panel: The left front curtain airbag wiring harness routes from the SRS ECU along the floor sill to the roof. After sill trim panel removal and installation or vehicle wading, a damaged harness protective sleeve causes the copper wire to contact the vehicle body metal.
  • 2Water ingress into A-pillar/B-pillar connector: The side curtain airbag connector is located inside the A-pillar upper trim panel or B-pillar interior trim panel. Leaks from a blocked sunroof drain hose or water ingress during a car wash cause a short circuit between the connector terminals or to ground.
  • 3Airbag module internal fault: Aging or manufacturing defects in the curtain airbag inflator internal bridge wire insulation cause a short to ground, typically associated with a history of operation in high-humidity environments.
  • 4SRS ECU drive circuit fault: ECU internal ignition drive-stage transistor breakdown causes a false short-to-ground detection. Measure the resistance between the ECU output terminal and ground to confirm.
  • 5Accident repair damage: After a side impact or roof repair, trim panel clips pinch the wiring harness, metal burrs cut the wires, or overly tight cable ties damage the insulation.
What To Do
  • 1
    Safe power-down and system discharge: Turn off the ignition, disconnect the low-voltage battery negative terminal, and wait at least 5 minutes (10 minutes for some models) to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Locate the physical connection point: Remove the left A-pillar upper trim panel, left B-pillar interior trim panel, and the front edge of the headliner. Find the dedicated yellow connector for the side curtain airbag (usually located above the A-pillar or B-pillar). Check the connector for oxidation, water ingress, or foreign matter.
  • 3
    Segmented resistance measurement: Disconnect the airbag module connector. Use a digital multimeter to measure the resistance between each of the two wires on the harness side (ECU side) and the vehicle body. If the resistance is <1Ω, the circuit shorts to ground. If the resistance is infinite, short the two harness wires and measure the airbag side. If continuity to ground exists, the airbag module has an internal short circuit.
  • 4
    Inspect the wiring harness section by section: If testing confirms a short circuit, open the corrugated conduit section by section from the ECU toward the airbag. Focus on the transition between the door sill and the A-pillar, and the pinch points at the harness retaining clips. After locating the damage, repair the insulation using double-layer heat-shrink tubing or replace the wiring harness assembly.
  • 5
    Component replacement verification: If the wiring harness is normal but the airbag module has an internal short circuit, replace the left front side curtain airbag module; if you suspect an ECU fault, cross-check with a known-good ECU.
  • 6
    System reset and verification: After repair, reconnect all connectors and the battery. Use the dedicated diagnostic tool to clear the fault code. Perform the SRS system self-check (usually including static and dynamic tests). Confirm B1762 does not return and the airbag warning light turns off. Finally, perform a road test to verify.
Real-World Cases
BYD DTC AI Analysis

Worn door sill wiring harness causes intermittent short circuit on Song MAX

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Vehicle: 2019 BYD Song MAX DM, 80,000 km. Symptoms: Airbag warning light comes on intermittently, with increased frequency in rain or on rough roads. Diagnosis: DTC B1762 stored as a history fault. Removed the left front sill trim and found the side curtain airbag wiring harness had chafed against the sill reinforcement beam retaining clip, wearing through the insulation to expose the copper wire. Over bumps, the wire contacted the body causing an intermittent short to ground. Solution: Repaired the damaged wiring with double-layer heat shrink tubing, rerouted the harness clear of sharp edges, and replaced the retaining clips with rubber-sleeved types. Fault resolved.
BYD DTC AI Analysis

Qin Pro EV A-pillar connector water ingress and corrosion

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Vehicle: Qin Pro EV 2019. Symptoms: Airbag warning light stayed on after heavy rain, accompanied by poor sunroof drainage. Diagnosis: Active fault B1762. Measured side curtain airbag harness resistance to ground at 0.3Ω. Inspection: Connector inside A-pillar upper trim showed green corrosion in the yellow plug; insulation resistance between terminals and to ground failed. Root cause: Sunroof left-front drain hose connector detached, letting rainwater run down the A-pillar into the connector. Solution: Cleaned and dried connector terminals, sprayed electronic contact cleaner, repaired drain hose connector, wrapped waterproof tape around the connector, and adjusted mounting angle to prevent water pooling. Fault cleared.
BYD DTC AI Analysis

Side Curtain Airbag Module Internal Short Circuit Replacement Case

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Vehicle: Song MAX petrol 2020 model, no accident history. Symptoms: Airbag warning light stays on; DTC B1762 cannot be cleared. Diagnosis: Disconnected the airbag module connector. Harness side ground resistance >10MΩ (normal). Both pins on the module side measure <1Ω to ground. Confirmed internal short to ground in the airbag igniter. Removed and inspected the airbag module (located in the left roof rail); found the internal bridge wire shorted to the metal housing. Resolution: Replaced the left front side curtain airbag assembly (including inflator), performed configuration coding. System back to normal.
BYD DTC AI Analysis

Short circuit from improperly secured wiring harness after accident repair

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Vehicle: 2020 BYD Qin Fuel, left front previously scraped in a collision. Symptoms: B1762 fault code appeared one month post-repair. Diagnosis: During the accident repair, the technician failed to route the side curtain airbag harness into the dedicated wire channel when installing the B-pillar trim panel, instead pinching it under the trim clips. Over time, the sharp clip edges cut through the harness insulation, causing a short to ground. Solution: Rerouted the harness, installed OEM harness retaining clips, repaired the damaged insulation. Fault cleared.
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.