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B17631A

DTC B17631A indicates the Right Front Side Curtain Airbag ignition circuit resistance is 0 ohms — Qin Plus

Safety System

DTC B17631A indicates the Right Front Side Curtain Airbag ignition circuit resistance is 0 ohms.

This means the control module detects a short circuit (short to ground or short to power) in the airbag circuit.

In the airbag system (SRS), normal inflator resistance ranges from 1.5Ω to 3.0Ω.

A 0-ohm resistance indicates abnormal circuit continuity, presenting the following risks: 1) The side curtain airbag fails to deploy during a collision, resulting in a loss of side impact protection. 2) The wiring short circuit causes unintended airbag deployment in extreme cases.

This constitutes a hard fault in the SRS and typically illuminates the SRS warning light continuously.

The system enters fail-safe mode and disables the Right Front Side Curtain Airbag.

5
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Airbag wiring harness short to ground: The right front curtain airbag wiring harness chafes inside the A-pillar, C-pillar, or headliner. Damaged insulation causes the wire to ground to the vehicle body, resulting in 0 resistance.
  • 2Airbag connector fault: Water ingress, oxidation, or bent pins in the headliner or door frame airbag connector cause a short circuit, creating continuity between the signal wire and ground.
  • 3Airbag unit internal short circuit: The curtain airbag inflator igniter has an internal short circuit (very rare, but a manufacturing defect may cause this).
  • 4SRS control module internal fault: A damaged internal monitoring circuit falsely reports a short circuit, while the actual wiring harness and airbag assembly are normal.
  • 5Clock spring or slip ring fault (if applicable): Although curtain airbags typically use direct wiring, a slip ring short circuit can cause this fault on models with movable connections.
What To Do
  • 1
    Safety preparation: Disconnect the battery negative terminal and wait at least 90 seconds (some models require 3 minutes) to fully discharge the SRS capacitor and prevent accidental airbag deployment during repair.
  • 2
    Visual inspection: Remove the right A-pillar trim, headliner edge, and right front door seal. Inspect the curtain airbag wiring harness for wear, crushing, or water ingress. Focus on contact points between the wiring harness and sharp metal body edges.
  • 3
    Connector inspection: Disconnect the connector between the SRS control module and the right front side curtain airbag. Inspect the pins for oxidation, deformation, or short circuits caused by foreign matter.
  • 4
    Resistance measurement: Use a multimeter to measure the airbag-side wiring harness resistance (expected: infinite/open circuit) and the airbag unit resistance (expected: 1.5-3.0Ω). If the airbag unit resistance is 0, replace the airbag assembly. If the wiring harness has continuity to ground, repair the wiring harness.
  • 5
    Wiring harness repair: If the wiring harness is damaged, wrap it with waterproof insulating tape or replace the harness section. Securely fasten the harness and ensure it does not interfere with metal body components.
  • 6
    Control module check: If the wiring harness and airbag assembly are normal, measure continuity between the corresponding pins on the SRS control module. If testing confirms an internal short circuit, replace the SRS control module.
  • 7
    System reset and verification: Reconnect all connectors and restore the battery power supply. Use the diagnostic tool to clear the fault code. Perform an SRS system self-check and confirm B17631A does not return. Verify the right front side curtain airbag resistance reads normal (1.5-3.0Ω).
Real-World Cases
BYD DTC AI Analysis

BYD Tang DM front passenger-side airbag harness chafed and shorted

✓
Symptoms: SRS warning light stayed on. Scan tool read DTC B17631A (right front side curtain airbag resistance 0 Ω). Diagnosis: 1. Disconnected the battery and removed the right A-pillar trim. Found the curtain airbag harness loose from its retaining clip below the A-pillar, chafing against a sharp metal body edge. 2. Peeled back the harness sleeve to expose two wires with damaged insulation; bare copper strands were touching the body and shorting to ground. 3. Measured the airbag unit resistance at 2.1 Ω (normal), confirming only the harness was faulty. Repair: Cut out the damaged 15 cm section. Repaired with same-colour, same-gauge wire using soldered connections and heat-shrink tubing. Re-secured the harness and added a rubber protective sleeve to prevent further wear. Cleared the DTCs; the SRS self-test passed and the warning light went out.
Original source ↗
BYD DTC AI Analysis

BYD Song Pro roof lining wiring harness connector shorted due to water ingress

✓
Symptom: Owner reported the airbag warning light illuminated after driving in rain, with DTC B17631A present. Diagnosis: 1. Inspected the right front side curtain airbag connector (located on the right side of the headliner) and found visible water stains and green oxide inside; 2. Measured resistance between connector pins and found continuity between the signal pin and ground pin (0.2Ω), confirming water ingress caused a short circuit; 3. Traced the leak to aged sealant around the roof rack mounting bolts, allowing rainwater to enter through the bolt holes into the headliner. Resolution: 1. Thoroughly cleaned the connector with electronic cleaner, dried it, and applied conductive grease; 2. Resealed the roof rack bolt holes; 3. Replace the wiring harness connector if the pins are severely corroded. Fault cleared after repair.
Original source ↗
BYD DTC AI Analysis

BYD Qin PLUS DM-i curtain airbag module internal short circuit

✓
Symptoms: SRS warning light illuminated suddenly at 5,000 km on a new vehicle. DTC B17631A would not clear. Diagnosis: 1. Disconnected the connector between the SRS control module and the right front side curtain airbag. 2. Measured resistance to ground on the airbag side harness: infinite (normal). Harness undamaged. 3. Measured resistance directly between the pins of the right front side curtain airbag gas generator: 0.3Ω (abnormal; normal range 1.5–3.0Ω). Internal airbag igniter shorted. Solution: Curtain airbags are safety components and internal shorts cannot be repaired. Replaced the right front side curtain airbag assembly (includes gas generator and airbag cushion). Performed system configuration and self-test after replacement. DTC cleared.
Original source ↗
BYD DTC AI Analysis

BYD Han EV SRS control module false positive fault

✓
Symptoms: Minor scrape (no impact to airbag sensors) caused airbag warning on dash. Stored DTC B17631A. Diagnosis: 1. Right front side curtain airbag harness visually intact; connectors normal. 2. Airbag resistance: 1.9Ω (normal). Harness continuity good; no short to ground. 3. SRS module output signal showed internal monitoring circuit false detection under light vibration. Solution: Replaced SRS control module (programmed to match vehicle VIN and airbag configuration). Performed system initialization learning after replacement. Fault resolved.
Original source ↗
BYD DTC AI Analysis

BYD Yuan Plus: Improper assembly pinched wiring harness, causing short circuit

✓
Symptoms: SRS warning light lit up one week after delivery. Scan showed DTC B17631A. Diagnosis: 1. Found the right front side curtain airbag harness pinched by an interior trim clip at the roof-to-body joint. 2. Removing the roof edge trim revealed the clip had pierced the harness insulation, letting copper wires touch the body metal and short. 3. Production line assembly error; harness routed off-spec. Repair: Repaired the harness (partial replacement). Re-routed per the workshop manual using dedicated retaining clips to clear hard interior trim. Checked other harnesses in the same location for similar damage before handover.
Original source ↗
Other Qin Plus 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.