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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 — Qin Plus

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 Qin Plus indicates high resistance in the airbag control unit's ground circuit, causing an unstable power supply and an illuminated SRS warning light. This medium severity fault may prevent airbag deployment. Common causes include a loose ground bolt or corroded ground terminal. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from 3 recorded cases.
3
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Ground point bolt loose or insufficiently torqued: Prolonged driving vibration loosens the SRS ECU ground bolt located on the instrument panel frame or center tunnel, increasing contact resistance.
  • 2Ground point oxidation or corrosion: Water wading, high-humidity environments, or battery leakage causes the ground terminal to rust or oxidize, forming an oxide layer that obstructs current flow.
  • 3Internal ground wiring harness damage: Crushing or excessive bending of the wiring harness during accident repairs completely or partially breaks the internal copper strands, causing hidden high resistance.
  • 4Poor connector contact: G36 connector terminals backed out, loose, or corroded, causing poor contact with the 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 repairs results in a poor ground connection.
What To Do
  • 1
    Connect the BYD dedicated diagnostic tool (VDS or ED400) to read fault codes, confirm B1693-00 is present, and record the freeze frame data.
  • 2
    Turn the power switch to OFF, disconnect the negative battery terminal, and wait at least 90 seconds for the SRS capacitor to fully discharge.
  • 3
    Locate the SRS ECU (usually below the center of the instrument panel or behind the glovebox) and find the G36 connector and body ground point.
  • 4
    Visually check the ground bolt for tightness. Check the ground wiring harness for damage or crush marks. Check the connector for water ingress or corrosion.
  • 5
    Disconnect connector G36. Use a multimeter to measure the resistance between wiring harness terminal G36-35 and a clean metal part of the vehicle body. The standard value must be less than 1Ω.
  • 6
    If resistance exceeds the limit, remove the ground bolt. Use sandpaper (400-600 grit recommended) to sand the wiring harness terminal contact surface and the vehicle body ground surface. Completely remove the oxide layer, paint, and rust until bare metal is exposed.
  • 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 fit.
  • 8
    If the wiring harness has breaks or internal damage, replace the SRS ECU-to-body ground wiring harness assembly. Do not repair the harness.
  • 9
    Remeasure the resistance between terminal G36-35 and ground to verify it is stable below 0.3Ω.
  • 10
    Connect the battery negative terminal, set the power mode to ON, and clear the fault code using the diagnostic tool. Check if the SRS light completes the 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.

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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 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.