AU
U1005-00

DTC U1005-00 indicates a short circuit between the Supplemental Restraint System (SRS) Controller Area Network (CAN) communication line and vehicle power (+B) — Qin Plus

Safety System

DTC U1005-00 indicates a short circuit between the Supplemental Restraint System (SRS) Controller Area Network (CAN) communication line and vehicle power (+B).

In BYD Qin series models, the Airbag Control Module (ACM) communicates with the vehicle network via the CAN bus.

When the CAN-H or CAN-L line shorts to constant power or ignition power, the short pulls the bus voltage up to 12V (battery voltage), distorting the CAN signal and interrupting communication.

This prevents the airbag system from receiving crash sensor signals or triggering airbag deployment, and may affect safety-related functions such as the seat belt pretensioners and the airbag warning lamp.

Because the CAN bus uses differential signal transmission, a short to power disrupts communication across the entire CAN network segment (typically including the instrument cluster and BCM).

This serious fault endangers driving safety.

The U1005-00 fault code on the Qin Plus indicates a high-severity short between the SRS CAN communication line and vehicle power. This can disrupt airbag system communication, seat belt pretensioners, and related safety functions. Common causes include damaged wiring where harnesses rub near the firewall or seat rails, or an internal Airbag Control Module fault. Stop driving if possible and visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
5
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Engine compartment or cabin wiring harness wear damages CAN and power wire insulation, causing them to contact each other, especially in high-wear areas such as the firewall pass-through and under the seat rails.
  • 2Airbag Control Module (ACM) internal transceiver circuit fault, CAN pin short to power, usually resulting from internal component breakdown.
  • 3After vehicle wading or heavy rain, water ingress and corrosion in SRS system connectors (such as floor harness connectors and under-seat connectors) cause a short circuit between the CAN line pins and power supply pins.
  • 4Mistakenly connecting the CAN line to the positive power supply during unauthorized modifications (such as installing a dashcam, large-screen navigation, or push-button start), or piercing the wiring harness, causing the power supply to contact the CAN line.
  • 5Improper body panel repair during accident repairs causes wiring harness retaining clips to detach. The harness contacts sharp edges, and long-term vibration wear causes a short circuit.
What To Do
  • 1
    Use VDS2000 or a dedicated diagnostic tool to read all fault codes. Confirm U1005-00 is a current fault, not a history fault. Check for accompanying U1004 (CAN short to ground) or other SRS communication fault codes.
  • 2
    Disconnect the 12V battery negative terminal and wait 3 minutes. Perform the high-voltage power-down procedure (for EV models). Remove the airbag control module (located in the center tunnel or under the instrument panel). Visually inspect the connector for water ingress, corrosion, or burn marks.
  • 3
    Use a multimeter to measure the resistance from harness-side CAN-H (orange/black) and CAN-L (orange/brown) to body ground. Normal resistance is greater than 1 MΩ. Measure the resistance to +B (constant power). Normal resistance is infinite. A resistance below 10 kΩ confirms a short circuit in the wiring harness.
  • 4
    If the wiring harness insulation is normal, reconnect the battery (do not disconnect the ACM connector). Turn the ignition ON and measure the CAN line voltage: normal CAN-H is approximately 2.5-3.5V, and CAN-L is approximately 1.5-2.5V. If the voltage is close to 12V, this indicates an internal short circuit in the ACM. Replace and recode the airbag control module.
  • 5
    If confirming a wiring harness fault, use the sectional troubleshooting method: start from the ACM connector and inspect along the floor wiring harness toward the instrument panel and crash sensor. Focus on wear-prone areas such as the firewall pass-through, under the seat slide rails, inside the A-pillar trim panel, and inside the sill wiring harness sleeve.
  • 6
    After locating the damage, repair the wiring harness (cut out the damaged section, solder, and insulate with heat-shrink tubing; do not simply wrap the wire). Check adjacent wires for damage and replace the entire wiring harness if necessary.
  • 7
    After repair, measure the CAN bus terminal resistance (Qin series SRS terminal resistance is typically 120Ω, and approximately 60Ω across the parallel bus). Confirm no short circuit exists, then reinstall all components.
  • 8
    Clear the fault code and perform an ignition cycle test. Confirm the SRS warning lamp turns off after a normal self-check. Use the diagnostic tool to confirm communication with the ACM is restored. Perform an airbag system function test.
Real-World Cases
BYD DTC AI Analysis

Qin EV300: Worn floor harness caused CAN short to power

✓
A 2017 Qin EV300 with 80,000 km displayed "Check SRS System" on the instrument cluster and the airbag warning light remained on. The scanner read DTC U1005-00. Inspection found the floor harness retaining clip beneath the driver's seat rail had detached. The harness had chafed against the seat rail, wearing through the CAN-H line insulation and shorting it to the seat heater power line (+B). Repair: Cut out the 20 cm damaged section, re-soldered and double-insulated the joint, replaced the retaining clip, and rerouted the harness clear of moving parts. This cleared the fault and restored normal communication.
BYD DTC AI Analysis

Qin 80: Airbag control module connector corroded after driving through water

✓
2017 BYD Qin 80 set DTC U1005-00 after wading through heavy floodwater, with a damp musty odour inside. Inspection found water had reached sill height. The airbag control module (ACM) connector seal under the centre console had degraded, letting water into the connector and causing electrolytic corrosion that shorted the CAN bus pins to constant power. Resolution: Disconnected the battery, thoroughly cleaned the connector terminals with precision instrument cleaner and ultrasonic cleaning, dried them with compressed air, applied conductive anti-corrosion grease, and replaced the waterproof seal. ACM internals were undamaged, so the module didn't need replacement. Also inspected and cleared the drain holes to prevent future water ingress.
BYD DTC AI Analysis

BYD Qin EV450: Aftermarket Large-Screen Navigation Triggered CAN Bus Fault

✓
A 2018 BYD Qin EV450 threw a U1005-00 code and the factory multi-function steering wheel stopped working after an aftermarket workshop fitted a third-party Android head unit. Inspection found the installer had tapped into the dashboard wiring harness CAN bus using insulation-piercing connectors to get a vehicle speed signal, but clamped the CAN-H line to the head unit's constant power (+12V), shorting the CAN bus to power. Repair: Removed the unauthorized wiring, cut out the damaged CAN section (approximately 15cm), resoldered the connections per factory wire order with proper insulation, and restored the original harness layout. Replaced the damaged CAN bus termination resistor (located in the dashboard harness). Restored the factory navigation system; fault cleared.
BYD DTC AI Analysis

Internal circuit breakdown in Qin 100 ACM caused short circuit

✓
A 2017 Qin 100 suddenly showed the airbag warning light during normal operation. Scanned U1005-00. Checked the harness—no damage or water ingress. Measured 12V on the CAN lines at the ACM connector. Disconnected the ACM and measured normal voltage (2.5V/2.3V) on the harness side. Confirmed the ACM’s internal transceiver circuit failed, shorting the CAN pins to internal power. The Qin 100’s ACM and airbag trigger IC are too highly integrated to allow separate circuit board repair. Replaced the OEM airbag control module (PN: BYD-3638100-X), coded and configured it using VDS2000, performed the airbag system calibration, and cleared the fault codes. System returned to normal.
BYD DTC AI Analysis

BYD Qin EV300: Wiring harness improperly secured after accident repair

✓
A Qin EV300 with front-end collision damage threw an intermittent U1005-00 code after dealership repairs. The crash repair replaced the instrument panel harness, but the firewall grommet was not installed correctly, letting the CAN harness contact the heater pipe bracket. Motor vibration rubbed the harness against the bracket, causing intermittent shorts to power (the bracket grounds to the body, but a nearby +12V wire had insulation damage). Fix: Reroute the instrument panel harness, secure with OEM clips, add a rubber grommet at the firewall, repair the damaged power wire insulation, and keep the harness 20mm clear of metal components. The fault has not returned.
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.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.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Qin Plus →Qin Plus overview →
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.