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 — Seal U

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 Seal U indicates high resistance in the airbag control unit's ground circuit, causing an unstable power supply and constant airbag warning light. Severity is medium. Common causes include loose earth bolts or corroded ground points. Visit an authorised dealer for inspection and repair. Typical repair cost data is available based on 3 recorded cases.
3
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Earth point bolt loose or insufficiently torqued: 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: Wading, high-humidity environments, 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 excessive bending of the harness during accident repairs breaks or partially breaks internal copper strands, causing hidden high resistance.
  • 4Poor connector contact: G36 connector terminals 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 repairs results 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 freeze frame data.
  • 2
    Turn the power mode to OFF, disconnect the 12V battery negative terminal, and wait at least 90 seconds for the SRS capacitor to fully discharge.
  • 3
    Locate the SRS ECU mounting position (usually below the center of the dashboard or behind the glove box), and find connector G36 and the body ground point.
  • 4
    Visually inspect the ground bolt for tightness, check the ground wiring harness for damage or crush marks, and check 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 must be less than 1 Ω.
  • 6
    If the resistance exceeds the limit, remove the ground bolt and 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 to expose 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). 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
    Re-measure the resistance to ground at terminal G36-35 and confirm it is stable below 0.3Ω.
  • 10
    Connect the battery negative terminal, set the power mode to ON, and use the diagnostic tool to clear the fault code. Observe if the SRS warning lamp completes the self-check normally (illuminates for 6 seconds, then turns off).
  • 11
    Perform a road test or simulated vibration test to verify 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 Seal U Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.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.B173712DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
Common problems reported for Seal U →Seal U 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.