AU
B1752

DTC B1752 indicates a short circuit to battery positive (B+) in the RHS Rear Side Airbag squib circuit — Atto 8

Safety System

DTC B1752 indicates a short circuit to battery positive (B+) in the RHS Rear Side Airbag squib circuit.

In the Supplemental Restraint System (SRS), normal airbag inflator resistance is 2-3 ohms.

The control unit determines circuit status by monitoring circuit current and voltage drop.

When wiring harness insulation damage causes a short to the 12V power supply wire, the control unit detects an abnormally high potential (near battery voltage) and triggers DTC B1752.

This fault causes the system to disable the affected airbag (fail-safe mode), preventing deployment during a collision.

Additionally, continuous current creates a risk of unintended airbag deployment.

The system classifies this as a level 3 severe fault.

5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Wiring harness wear inside the right B-pillar trim panel: Frequent rear passenger entry and exit or seat adjustment wears the harness sleeve between the B-pillar and the seat, shorting the copper wire to the body power supply wire.
  • 2Water ingress into under-seat connector: Water seeps into the airbag wiring harness connector under the right rear seat during vehicle wading or interior cleaning, causing a short circuit or conductive corrosion between terminals.
  • 3Airbag module internal fault: Abnormally low igniter resistance or an internal short circuit in the right rear side airbag assembly causes abnormal circuit resistance.
  • 4Wiring harness damage after accident repair: During a right-side collision or repair work, harness clips or sharp metal edges pinched the wiring harness in the B-pillar, sill, or C-pillar area, damaging the insulation.
  • 5SRS control unit internal drive circuit fault: A damaged ignition driver chip or monitoring circuit inside the airbag control module falsely reports a short to power.
What To Do
  • 1
    Safety preparation: Disconnect the 12V battery negative terminal and wait at least 90 seconds to fully discharge the SRS capacitor. Wear an anti-static wrist strap. Do not use radio equipment near the airbag assembly.
  • 2
    Initial diagnosis: Use a Launch X-431 or BYD dedicated diagnostic tool to read all SRS fault codes, check for B1752 and accompanying fault codes (such as B1751 short to ground), and record the freeze frame data.
  • 3
    Visual inspection: Remove the right B-pillar lower trim panel, right rear door sill trim panel, and right rear seat. Inspect the wiring harness for damage or burn marks, focusing on movement interference points between the seat and the B-pillar.
  • 4
    Electrical measurement: Disconnect the airbag control unit connector (note the shorting bar). Use a multimeter to measure the voltage to ground in the right rear side airbag circuit (usually corresponding to the connector pins). The normal value is less than 1V. A 12V reading confirms a short to power.
  • 5
    Section isolation: Disconnect the right rear side airbag module connector. Measure the wiring harness side and the airbag side separately. If 12V remains on the wiring harness side, the wiring harness is faulty. If the wiring harness side is normal but the airbag side is shorted, replace the airbag module.
  • 6
    Wiring harness repair: If the wiring harness is damaged, repair it using waterproof heat-shrink tubing or replace the wiring harness assembly. Route the harness away from seat slide rails and sharp metal edges, and re-secure the retaining clips.
  • 7
    Component test: After repair, reconnect all connectors. Use the diagnostic tool to perform the 'Airbag System Function Test' or 'Actuator Test'. Confirm B1752 becomes a history fault code and can be cleared.
  • 8
    Final verification: After clearing the fault code, road test the vehicle and perform multiple ignition cycles to confirm the fault code does not return. Verify the SRS warning light turns off normally.
Real-World Cases
BYD DTC AI Analysis

Song MAX: Right rear seat adjustment chafing B-pillar wiring harness

✓
A 2019 Song MAX with 32,000 km had the SRS warning light staying on. Retrieved DTC B1752. Removing the right B-pillar trim revealed the airbag harness sheath at the gap between the seat frame and B-pillar inner lining had worn through, caused by frequent second-row seat adjustments. The exposed copper wires shorted directly to the vehicle power wiring. Repair: Replaced the B-pillar-to-seat wiring harness assembly (part number 4G-5826934), added rubber protective sleeves and cable ties at wear points, and rerouted the harness away from moving parts. The repair cleared the fault. No recurrence at three-month follow-up.
BYD DTC AI Analysis

Tang DM airbag connector corroded and shorted after water wading.

✓
2021 Tang DM drove through standing water after heavy rain. The next day, the dashboard displayed 'Check Airbag System'. The scan tool retrieved codes B1752 and B1751 (short to ground). Inspection found the right rear carpet wet. Removing the airbag connector (yellow plug) under the seat revealed mud and water inside; electrolytic corrosion between the terminals created a conductive path. Cleaned the connector with anhydrous alcohol, dried it with compressed air, applied conductive grease, and replaced the waterproof seal. Also checked the sunroof drain tube for blockages to prevent further water ingress. After clearing the codes, the system returned to normal.
BYD DTC AI Analysis

Yuan EV wiring harness pinched after accident repair, causing short circuit

✓
A 2019 BYD Yuan EV sustained minor collision damage to the right rear side. Following repairs at an independent workshop, DTC B1752 appeared. Inspection at the dealer revealed that during installation of the B-pillar trim, the technician had trapped the airbag wiring harness between the metal clip and plastic trim panel. Long-term compression damaged the insulation, allowing the harness copper wires to contact the body's 12V constant power wire. Solution: Repaired the damaged harness section, rerouted the wiring to avoid running parallel to the power wire, wrapped it with fleece tape, and installed the trim clips to standard torque. Recoded and calibrated the airbag control unit.
BYD DTC AI Analysis

Internal short circuit in right rear side airbag module (Qin Pro)

✓
A 2020 BYD Qin (petrol) flagged a B1752 fault code. After disconnecting the airbag module connector, the harness side measured normal (no short to power), but the airbag module pins measured 0.5 ohms (normal range: 2-3 ohms). This indicated an internal igniter short in the airbag assembly. Replaced the right rear side airbag module (part number SCE-5826910) and the fault cleared. The cause: either the propellant inside the airbag had become damp or a manufacturing defect caused insulation failure between the igniter terminals.
BYD DTC AI Analysis

Intermittent fault caused by SRS control unit false alarm

✓
A 2019 Tang intermittently set B1752 on cold starts; the code cleared once warm. The wiring harness tested normal for continuity and insulation. Airbag circuit voltage measured an abnormal 12V during the fault. Inspection revealed slight oxidation on the SRS control unit (ACU) connector pins, causing reference voltage drift in the monitoring circuit. Cleaning the connector, applying electronic contact cleaner, and upgrading the ACU software from V2.1 to V2.3 to optimize the ignition circuit monitoring threshold resolved the issue. The fault has not returned.
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.