AU
B1752-00

DTC B1752-00 indicates the right rear side airbag igniter circuit is shorted to vehicle power (B+) — Atto 8

Safety System

DTC B1752-00 indicates the right rear side airbag igniter circuit is shorted to vehicle power (B+).

In the SRS (Supplemental Restraint System) circuit architecture, the airbag igniter is a low-impedance (nominal 2-5Ω) resistance wire.

Normally, the SRS control unit uses an internal boost circuit to supply a momentary high current (approx. 1-3A) to deploy the airbag during a collision.

Detecting a short to the 12V power supply in the igniter harness indicates an abnormal high-potential path in the circuit.

This creates two risks: first, continuous power supply may cause accidental airbag deployment without a collision (although modern SRS controllers typically feature short-circuit protection); second, during an actual collision, the external power short prevents the control unit from forming an effective current loop to deploy the airbag, disabling the safety function.

Consequently, the SRS control unit immediately illuminates the airbag warning lamp, stores this DTC, disables the right rear side airbag and related linked protection functions, and enters fail-safe mode.

5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Long-term bending and wear at the seat frame hinge damages the right rear seat side airbag wiring harness insulation, causing a short circuit to the seat heating or adjustment motor power wire.
  • 2Frequent folding or lowering of the rear seat, or modifying seat covers, causes the seat rails or metal frame to pinch the wiring harness, damaging the wire insulation and causing a short to power.
  • 3Water ingress and corrosion at the airbag connector (yellow plug) at the right rear C-pillar or under the seat (commonly due to aged sunroof drain tube leaks or vehicle wading) causes electrolyte conduction between terminals, creating a short circuit.
  • 4Power transistor breakdown in the airbag control unit (SRS ECU) internal ignition drive circuit, causing continuous 12V output to the igniter circuit.
  • 5During accident repair or interior trim removal and installation, missing wiring harness retaining clips cause the harness to shift, rub against sharp metal body edges, sustain damage, and contact a power wire.
What To Do
  • 1
    Safety preparation: Turn the power switch to OFF, disconnect the negative battery terminal, and wait at least 3 minutes (to fully discharge the SRS energy storage capacitor). Never measure the airbag circuit while energized.
  • 2
    Visual inspection: Remove the right rear seat and lower C-pillar trim panel. Check the right rear side airbag module connector (usually located on the side of the seat back or below the C-pillar) for looseness, water ingress, corrosion, or foreign objects. If necessary, clean with electrical contact cleaner and blow dry.
  • 3
    Circuit measurement: Disconnect the airbag module connector. Use a high-impedance multimeter to measure the voltage between the harness-side terminal and ground. Normal voltage is less than 1V. A 12V reading confirms a short to power. Measure the resistance between the terminal and ground. Normal resistance is greater than 1MΩ.
  • 4
    Fault isolation: If the measurement is abnormal, inspect along the routing of the yellow wiring harness sleeve. Focus on wear-prone areas such as the seat folding mechanism, guide rail mounting points, and C-pillar sheet metal holes. Repair damaged wiring harnesses (re-wrap or replace the harness section) and maintain a clearance of at least 20mm from the power cable.
  • 5
    Component replacement verification: If the wiring harness is normal, replace the original airbag module with a 2-3Ω non-inductive resistor (or dedicated airbag simulator). Restore the connection, power on the vehicle, clear the fault code, and perform an SRS self-check. If the fault disappears, confirm an internal short circuit in the airbag module and replace the right rear side airbag module (store the new part flat and away from heat sources).
  • 6
    System reset: After confirming fault resolution, reinstall all connectors and trim panels, connect the battery, use the BYD dedicated diagnostic tool (VDS or EDS) to clear the fault codes, and perform the 'SRS System Self-Learning' and 'Crash Sensor Configuration' procedures.
  • 7
    Function check: Set the power mode to ON and observe that the airbag warning light on the instrument cluster turns off after the 6-second self-check. Perform a road test simulating bumpy road conditions to confirm the fault code does not recur.
Real-World Cases
BYD DTC AI Analysis

Frequent folding of the right rear seat caused the wiring harness to wear through and short circuit.

✓
A 2018 BYD Qin EV450 with 80,000 km showed an airbag warning light on the dash. VDS pulled fault code B1752-00. The owner said they often used the car for hauling cargo, keeping the right rear seat folded down for long periods. Removing the seat revealed the side airbag wiring harness insulation had completely worn through at the seat frame hinge, exposing copper wire that shorted against the seat heater pad power line. Repair: replaced the damaged wiring section, fitted abrasion-resistant corrugated tubing, re-routed the harness, and added retaining clips to prevent flexing during seat movement. Fault resolved.
BYD DTC AI Analysis

C-pillar water leak caused airbag connector corrosion and short circuit

✓
2017 Qin 100 airbag warning light remained on after heavy rain, with DTC B1752-00. Found water inside the right rear C-pillar trim. The rear sunroof drain hose connector had deteriorated and detached, allowing rainwater to run down the C-pillar. The right rear side airbag connector (yellow) below the C-pillar had corroded from water ingress; oxide layers and electrolyte on the terminals caused a short to power. Repair: Unclogged and replaced the sunroof drain hose, removed water from the C-pillar, thoroughly cleaned the connector with electrical contact cleaner and applied conductive grease, blow-dried and left for 24 hours, then reinstalled and road tested. Fault resolved.
BYD DTC AI Analysis

Airbag module internal short circuit false alarm.

✓
No collision history. DTC B1752-00 sets intermittently and returns days after clearing. Disconnected the airbag module connector and measured the harness side – voltage <0.1V, resistance to ground >10MΩ. Substituted a 2.5Ω resistor for the airbag module to simulate the load and monitored continuously for one week without fault recurrence. Found insulation deterioration on the igniter resistor wire inside the right rear side airbag module, causing an internal short to the capacitor terminal. Replaced with a genuine airbag module (part number matches VIN), performed SRS configuration, and resolved the fault completely.
BYD DTC AI Analysis

Seat removal and refitting pinched the wiring harness, causing a short circuit.

✓
The vehicle developed DTC B1752-00 the day after an unauthorised repair shop replaced the right rear seat leather cover. Inspection at the dealership revealed that during seat installation, the technician had failed to properly clip the airbag wiring harness into the retention slot on the seat frame. The seat rails pinched the harness, and the metal edge cut the insulation during electric seat adjustment, causing a short to the seat motor power supply wire. Repair procedure: Rerouted the harness into the dedicated wiring channel, wrapped the damaged section with felt tape (copper core unaffected), fitted abrasion-resistant sleeving, and reinstalled the retaining clips. Cleared the fault code and verified normal operation through multiple seat adjustment cycles. Fault resolved.
BYD DTC AI Analysis

SRS control unit internal driver circuit fault

✓
After ruling out the wiring harness and airbag module, the fault remained. I measured a constant 12V at the SRS ECU drive terminal for the right rear side airbag (normally 0V; it should supply voltage only upon crash trigger). I removed the SRS control unit (under the centre console) and found the power MOSFET in the internal ignition drive circuit had short‑circuited, sending constant voltage to the igniter circuit. Since the control unit is a safety component and cannot be serviced separately, I replaced the SRS control unit assembly, carried out online coding (entering the vehicle VIN and configuration code), and calibrated the collision sensors to clear the fault.
Other Atto 8 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.