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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 — Seal 6 EV

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.

3
Cases Logged
Real-World Cases
BYD DTC AI Analysis

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

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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.
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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.
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BYD DTC AI Analysis

Ground point oxidation fault on BYD Surui after wading through water

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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.
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Other Seal 6 EV 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.B110811This DTC indicates a short circuit in the air conditioning system PM2.5 air quality sensor (rapid detector). Specifically, abnormal continuity exists between the sensor power supply circuit or signal output circuit and body ground or battery positive. This causes the control module (ACU/air conditioning controller) to detect abnormal current or a voltage signal outside the valid range (typically 0V or supply voltage). The PM2.5 sensor monitors internal and external particulate concentrations, providing the data the automatic air conditioning system uses to switch between fresh air and recirculation modes. A short circuit disables the air quality monitoring function. This fault may force the air conditioning system into recirculation protection mode and trigger related thermal management system faults, as the air conditioning system acts as a key actuator in vehicle thermal management. In severe cases, the short circuit current can damage the internal sampling circuit of the air conditioning controller or overheat the wiring harness.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.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.
Data confidence: Community This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.