This content was compiled automatically and has not yet been reviewed by a technician. For reference only.
For reference only. Always confirm part numbers and procedures for your specific vehicle.
Fault diagnosis
BYD F3DM B1234: Repair case of severe battery pack electrical leakage and failure to enter OK
After prolonged parking, the vehicle cannot enter OK; red engine and motor warning lights remain on after low-voltage recharging.
BYD F3DM B1234: Repair case of severe battery pack electrical leakage and failure to enter OK
Symptoms
- After prolonged parking, the vehicle cannot enter OK; red engine and motor warning lights remain on after low-voltage recharging. [1]
Diagnostic trouble codes
- B1234 (manufacturer): Severe battery pack electrical leakage (original diagnostic-tool definition in Fig.3; only applies to this case) [1]
Possible causes
- After ruling out insulation abnormalities on the load side and external output cables, the case found corrosion of the battery housing, poor sealing and water ingress, with damage to two internal module groups. [1]
Checks
- First check low-voltage power supply and current codes; a qualified technician capable of high-voltage work must follow the model-specific power isolation, discharge waiting, insulation protection and absence-of-voltage verification procedures to distinguish the load side from the battery side. Only diagnostic clues for isolating sections are retained here; no steps for opening an energised battery pack are provided. [1]
What to do
- In the original case, OK was restored after addressing the damaged modules, balancing and retesting; this only records the outcome and does not present replacement of old modules as general repair advice. [1]
Applicability and limits
- Source limits: BYD F3DM, 2011 model year; a single-vehicle repair case. The code definition is limited by the model and diagnostic system; do not extend to other BYD models. For inspection clues only; related parts do not constitute a replacement recommendation. No vehicle model has been linked; do not assume applicability to other models of the same brand. Scope: unknown [1]
- Single-vehicle repair case; the code definition is limited by the model and diagnostic system. Do not extend to other BYD models
Related part categories
- Traction battery modules [1]
- Traction battery sealing components [1]
Sources
[Source 1] BYD F3DM Severe Battery Pack Electrical Leakage Troubleshooting | Repair Case — "Fault symptoms", Fig.3; "Fault diagnosis and repair", Figs.10–11 and final paragraph (accessed 2026-11-01)
https://www.casstime.com/index/news/detail/id/1715.html
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