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) — Atto 3

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 Atto 3 indicates a high-severity short circuit between the SRS CAN communication line and vehicle power. This can disrupt airbag and seat belt pretensioner communication, creating a safety risk. Common causes include damaged wiring where CAN and power wires contact, or an internal Airbag Control Module fault. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Chafed engine compartment or cabin wiring harness damages CAN and power wire insulation, causing the wires to contact, 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 shorted to power, usually resulting from internal module component breakdown.
  • 3After driving through water or heavy rain, water ingress and corrosion in SRS system connectors (such as floor wiring harness connectors and under-seat connectors) cause a short circuit between the CAN line pins and power supply pins.
  • 4Incorrectly connecting the CAN line to the positive power supply during unauthorized modifications (such as installing a dash cam, large-screen navigation, or push-button start), or a pierced wiring harness causing the power supply to contact the CAN line.
  • 5Improper sheet metal repair during accident repairs causes wiring harness retaining clips to detach, allowing the harness to contact sharp edges and short circuit due to long-term vibration wear.
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 an accompanying U1004 (CAN short to ground) or other SRS communication fault codes.
  • 2
    Disconnect the 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 signs of water ingress, corrosion, or burning.
  • 3
    Use a multimeter to measure the resistance from the 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 (battery positive). Normal resistance is infinite. If the resistance is less than 10 kΩ, this 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 2.5-3.5 V, and CAN-L is approximately 1.5-2.5 V. A voltage near 12 V indicates an internal short circuit in the ACM. Replace and recode the airbag control module.
  • 5
    After confirming a wiring harness fault, use the sectional troubleshooting method: start from the ACM connector and inspect along the floor wiring harness towards the instrument panel and crash sensor. Focus on high-wear areas such as the firewall pass-through, under the seat slide rail, 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). Inspect adjacent wires for damage and replace the entire wiring harness if necessary.
  • 7
    After repair, measure the CAN bus terminating resistance (Qin series SRS terminating resistance is typically 120Ω, and approximately 60Ω with the bus in parallel). Confirm no short circuits exist, then reinstall all components.
  • 8
    Clear the fault code and perform an ignition cycle test. Confirm the SRS warning light 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 Atto 3 Fault Codes
P0AA6Hybrid Battery Voltage System Isolation FaultB1108For 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.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.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.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.
Common problems reported for Atto 3 →Atto 3 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.