P3445critical severityPowertrain
BMS Communication Bus Fault
on 2010 Toyota Highlander 3.3L V6 Hybrid · AWD
What this code means
The BMS internal communication bus connecting cell monitoring boards has a fault, preventing full battery monitoring.
Symptoms
- Partial battery data unavailable
- Power output limited as precaution
- Some cell voltages read as zero
- BMS warning indicator
- Charging may be limited
Common causes
- Internal CAN/SPI bus wiring fault
- Cell monitoring board failure
- Connector between modules loose
- EMI affecting internal communication
- BMS main controller port failure
Diagnostic steps
- Read BMS internal communication status
- Identify which monitoring board is affected
- Check internal bus termination
- Inspect inter-module connectors
- Test communication bus signal quality
Repair notes
Repair internal BMS communication bus. Replace affected cell monitoring board. Re-seat internal connectors.
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