AU
B1708-00

BYD defines DTC B1708-00 as "Seat Driver Recline Rearward Switch Circuit Short To Ground", a body electrical system fault — Atto 8

Safety System

BYD defines DTC B1708-00 as "Seat Driver Recline Rearward Switch Circuit Short To Ground", a body electrical system fault.

This fault indicates the Seat Control Unit (SCU) detects an abnormal 0-ohm resistance (short to ground) in the driver seat recline rearward switch circuit.

Possible causes include switch contacts stuck closed, damaged harness insulation causing a short to ground, or connector water ingress.

This fault prevents rearward seat adjustment, causes uncontrolled continuous rearward movement, or disables the seat memory function.

Some third-party data sources incorrectly label this code as "left curtain airbag resistance is 0".

Airbag faults typically use the B10XX-B19XX range or dedicated SRS fault codes, and standard OBD-II assigns B1708 to the seat adjustment circuit.

5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Burnt internal contacts, a deformed spring plate, or water ingress in the driver seat backrest rearward adjustment switch causing a permanently closed short circuit.
  • 2Frequent forward and backward seat movement chafes the under-seat wiring harness, wearing through the insulation and exposing the copper wire, resulting in a short to ground.
  • 3Poor sealing of the seat wiring harness connector. Water ingress and oxidation after washing the vehicle or wading causes a short circuit between pins or a short to ground.
  • 4Improper modifications (such as floor mat retaining clips or aftermarket seat heaters) pierced or crushed the seat wiring harness.
  • 5Seat Control Module (SCU) or Body Control Module (BCM) internal driver circuit fault (low probability)
What To Do
  • 1
    Use the BYD dedicated diagnostic tool (BYD-EDS or Launch X-431) to read the fault codes. Confirm if B1708-00 is a current (Active) or historical (History) fault, and check for other accompanying seat fault codes.
  • 2
    Visually inspect the wiring harness under the driver's seat and near the seat rails. Check friction points against the metal frame and areas with an excessively small bend radius for damage, discoloration, or signs of water ingress.
  • 3
    Disconnect the seat adjustment switch connector. Use a multimeter to measure the resistance of the rearward adjustment position on the switch side. The normal reading is open circuit (OL). If the resistance is close to 0Ω, replace the switch assembly.
  • 4
    Measure harness-side resistance to ground (with SCU and switch disconnected). If continuity to ground exists, inspect the wiring harness section by section. Focus on the seat slide rail retaining clip and the wiring pass-through hole below the steering column.
  • 5
    If the wiring harness is damaged, repair the insulation with heat-shrink tubing or corrugated conduit, and adjust the harness retaining clips to increase slack. If the switch is shorted, replace the driver seat multi-directional adjustment switch assembly.
  • 6
    Check the seat control module software version. If necessary, update to the latest version to eliminate false codes.
  • 7
    After completing the repair, clear the fault code. Test the seat forward/backward, up/down, and backrest multi-angle adjustments to verify the memory function sets and recalls normally.
Real-World Cases
BYD DTC AI Analysis

BYD Qin Pro DM seat wiring harness worn through, causing short circuit

✓
Symptoms: Body system warning light illuminated on the instrument cluster. Diagnostic scan retrieved DTC B1708-00. Driver seat backrest rearward adjustment button inoperative. Diagnosis: Wiring harness connector beneath the driver seat found oxidised and loose. Frequent seat movement wore through the harness insulation, allowing internal wires to contact the vehicle body and short to ground. Repair: Replaced the driver seat backrest rearward adjustment switch assembly. Re-wrapped and secured the wiring harness beneath the seat. Fitted a protective sleeve to prevent future abrasion.
Original source ↗
BYD DTC AI Analysis

BYD Song PLUS EV seat switch shorted due to water ingress

✓
Symptom: Driver's seat adjustment failed suddenly while operating, and the memory function stopped working. Diagnostic scanner found DTC B1708-00 in the Seat Control Module (SCU). Disassembly found water ingress inside the side adjustment switch panel (owner spilled a drink). Testing confirmed a short circuit (abnormal continuity) in the rearward adjustment position. Repair: Replaced driver's seat adjustment switch assembly, applied waterproofing to seat harness connectors, and recalibrated memory function. All functions returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM-i seat wiring harness intermittent short circuit

✓
Symptoms: The dealership found historical fault code B1708-00 during a routine service. The owner had not noticed any obvious fault. Diagnosis: intermittent fault. While simulating seat fore/aft movement, the harness experienced excessive tension at extreme positions, causing momentary short circuits. Testing revealed microscopic damage to the harness insulation. Solution: Adjusted seat harness clip positions to increase slack, replaced the damaged harness segment, and installed high-grade abrasion-resistant protective conduit.
Original source ↗
BYD DTC AI Analysis

BYD Yuan Pro seat switch internal contacts deformed

✓
Symptoms: Driver seat backrest would not adjust rearward; forward adjustment worked normally. Scan tool retrieved DTC B1708-00. Removed the switch and tested it: pressing the rearward adjustment button gave a resistance reading near 0 ohms (normal should be several hundred ohms). Disassembled the switch and found the internal contact spring plate had deformed, causing a constant short circuit. Solution: Replaced the driver seat multi-way adjustment switch assembly. Checked the related wiring harness, found no faults, then reinstalled the components.
Original source ↗
BYD DTC AI Analysis

Modified clip pierced the BYD e2 seat wiring harness.

✓
Symptoms: Upon startup, the seat automatically moved to the rearward limit and could not be adjusted back. Diagnosis found the rearward adjustment switch stuck closed. The cause was traced to retaining clips from aftermarket floor mats piercing the wiring harness under the seat, shorting the power and signal wires. Resolution: Removed the improperly installed mat clips, repaired and re-insulated the damaged harness, replaced the seat adjustment switch damaged by the short circuit, and recalibrated the seat position memory function.
Original source ↗
Other Atto 8 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: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.