AU
B1693-00

DTC B1693-00 indicates high resistance or an intermittent open circuit in the Supplemental Restraint System (SRS) Electronic Control Unit (ECU) ground circuit — Atto 3

Safety System

DTC B1693-00 indicates high resistance or an intermittent open circuit in the Supplemental Restraint System (SRS) Electronic Control Unit (ECU) ground circuit.

Specifically, the resistance of the ground path from the SRS ECU through connector G36 (specifically terminal G36-35) to the main body ground point exceeds the calibrated threshold (normally less than 1Ω).

This fault causes an unstable ECU power supply reference potential, triggers a system self-check failure, and continuously illuminates the airbag warning lamp (SRS lamp).

In extreme cases, this condition prevents airbag deployment during a collision or causes unintended deployment, severely compromising passive safety system functionality.

The B1693-00 fault code on the Atto 3 indicates high resistance or an intermittent open circuit in the SRS (airbag) control unit ground circuit, causing an unstable power supply and illuminated airbag warning light. This medium severity fault may prevent airbag deployment or cause unintended deployment. Common causes include loose or corroded ground connections at the instrument panel frame or centre tunnel. Visit an authorised dealer for inspection. Typical repair cost data is available based on 3 recorded cases.
3
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Loose earth point bolt or insufficient torque: Prolonged driving vibration loosens the SRS ECU earth bolt located on the instrument panel frame or centre tunnel, increasing contact resistance.
  • 2Ground point oxidation or corrosion: Water ingress, high humidity, or battery leakage causes the ground terminal to rust or oxidize, forming an oxide layer that obstructs current flow.
  • 3Internal damage to the ground wiring harness: Crushing or excessively bending the wiring harness during accident repairs breaks or partially breaks the internal copper strands, resulting in hidden high resistance.
  • 4Poor connector contact: G36 connector terminals are backed out, loose, or corroded, causing poor contact with ECU pins.
  • 5Improper treatment of the body ground terminal: Failure to remove paint, sealant, or coating from the body surface at the ground point after repair, resulting in a poor ground connection.
What To Do
  • 1
    Connect the BYD dedicated diagnostic tool (VDS or ED400) to read the fault code, confirm B1693-00 is present, and record the freeze frame data.
  • 2
    Turn the power mode to OFF, disconnect the battery negative terminal, and wait at least 90 seconds to fully discharge the SRS capacitor.
  • 3
    Locate the SRS ECU mounting position (usually below the center of the dashboard or behind the glovebox) and find connector G36 and the body ground point.
  • 4
    Visually inspect the ground bolt tightness, check the ground wiring harness for damage or crush marks, and inspect the connector for water ingress or corrosion.
  • 5
    Disconnect connector G36. Use a multimeter to measure the resistance between harness-side terminal G36-35 and a clean metal part of the vehicle body. The standard value is less than 1Ω.
  • 6
    If the resistance exceeds the limit, remove the ground bolt. Use sandpaper (400-600 grit recommended) to sand the contact surface of the wiring harness terminal and the vehicle body ground surface. Completely remove the oxide layer, paint, and rust to expose shiny bare metal.
  • 7
    Apply conductive paste (anti-oxidation conductive compound) evenly to the contact surface, reinstall the ground bolt, and tighten it to the specified torque (usually 10-12 N·m) to ensure a secure installation.
  • 8
    If the wiring harness has breaks or internal damage, replace the SRS ECU-to-body ground wiring harness assembly; do not repair it.
  • 9
    Remeasure the resistance between terminal G36-35 and ground to confirm it remains stable below 0.3 Ω.
  • 10
    Connect the battery negative terminal, switch the power mode to ON, and use the diagnostic tool to clear the fault code. Verify the SRS warning light completes its self-check normally (illuminates for 6 seconds, then turns off).
  • 11
    Perform a road test or simulated vibration test to confirm the fault does not recur.
Real-World Cases
BYD DTC AI Analysis

Loose ground point on BYD S6/S7 causing SRS warning light

✓
Symptoms: After starting the vehicle, the SRS warning light on the dashboard stays on. The scan tool read DTC B1693-00 (poor ground connection). Diagnosis: The technician inspected the airbag ECU ground point (located near the dashboard frame) and found the ground bolt loose. They disconnected the G36 connector and measured 3.5Ω resistance between terminal G36-35 on the harness side and body ground (standard value should be less than 1Ω), indicating poor grounding. They also found slight oxidation on the ECU housing ground contact surface. Resolution: They removed the ground bolt and sanded the body ground end and harness terminal with sandpaper to remove the oxidation layer. They reinstalled and tightened the ground bolt to the specified torque of 10-12 N·m. They remeasured the resistance between G36-35 and body ground; it returned to 0.3Ω. They connected the diagnostic tool and cleared the fault code. After a normal self-check, the SRS light went out. Fault resolved.
Original source ↗
BYD DTC AI Analysis

BYD Qin: wiring harness damaged after accident repair caused B1693-00.

✓
After front collision repairs on a BYD Qin, the airbag warning light remained on. A scan tool retrieved DTC B1693-00 with the description "poor ground connection". The technician followed the Qin SRS diagnostic procedure for DTC B1693-00 and inspected the power and ground circuits for the airbag ECU. The ground point was not loose, but the resistance between terminal G36-35 and chassis ground fluctuated between 2Ω and 10Ω, and the voltage to ground was not 0V (indicating a voltage drop). Tracing the harness revealed it had been pinched during the accident repairs, partially breaking the copper strands inside the ground wire and causing poor contact. Replaced the ground harness assembly between the SRS ECU and the main chassis ground point. Remeasured the resistance between G36-35 and chassis ground; it stabilized at 0.2Ω (below the 1Ω specification). Verified the airbag ECU case ground was good. Cleared the DTC and road-tested the vehicle; the SRS light remained off and the system returned to normal.
Original source ↗
BYD DTC AI Analysis

Ground point oxidation fault on BYD Surui after wading through water

✓
Symptoms: The owner reported the airbag warning light illuminated on the instrument panel after driving through water. Diagnostic equipment retrieved fault code B1693-00 (poor earth connection). Other vehicle functions remained normal. Diagnosis: The technician consulted the BYD Surui SRS system fault code list and confirmed B1693-00 indicates an earth connection issue. The technician inspected the SRS ECU earth point located at the cabin floor (near the pedals) and found water stains and rust from the water ingress. The technician measured resistance between this earth point and the vehicle body at 15Ω, far exceeding the standard value (less than 1Ω), determining oxidation had caused poor earthing. The technician inspected connector G36 and confirmed the terminals showed no corrosion, though the earth bolt showed signs of rust. Solution: The technician thoroughly cleaned the earth point, used a dedicated cleaner to remove rust, and applied conductive paste to prevent further oxidation. If corrosion is severe, replace the earth bolt and earth terminal with new ones. After treatment, resistance dropped below 0.5Ω. The technician cleared the fault code; the SRS system self-test passed, and the warning light went out.
Original source ↗
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.