VCFRONT_a478 — LVBMS MOSFET Open

Full alert identifier: VCFRONT_a478_LVBMS_MOSFET_Open

Message shown in the car

Low voltage battery service is required Schedule service - Vehicle may not restart

Alert description

The low voltage battery management system (LVBMS) has opened the low voltage (LV) battery's internal protection transistor (MOSFET), disconnecting the LV battery from the rest of the vehicle electrical systems.

Potential impact

The LV battery is unable to support vehicle electrical systems or to recharge via the power conversion system (PCS). The high voltage (HV) system will remain energized to continue supplying electrical power to the vehicle while the LV battery is unavailable. This may result in greater range loss than expected, increased HV system energy consumption when the vehicle is idle, and prevent the vehicle from sleeping.

Set condition

The LVBMS reports the LV battery's internal protection transistor (MOSFET) is open.

Clear condition

The LVBMS reports the LV battery's internal protection transistor (MOSFET) is closed again.

Signals to check

These diagnostic fields are associated with VCFRONT_a478. Check the alert's Payload in Service Mode Plus for available values.

Signal	Unit
Bms mia `VCFRONT_a478_BMS_MIA`	—
HV Blocking Mismatch `VCFRONT_a478_HVBlockingMismatch`	—
Hv up `VCFRONT_a478_HV_UP`	—
Pcs mia `VCFRONT_a478_PCS_MIA`	—
Batt Fault Cell Over Voltage `VCFRONT_a478_battFaultCellOverVoltage`	—
Batt Fault Cell Under Voltage `VCFRONT_a478_battFaultCellUnderVoltage`	—
Batt Fault Charge Over Current `VCFRONT_a478_battFaultChargeOverCurrent`	—
Batt Fault Hardware Over Current `VCFRONT_a478_battFaultHardwareOverCurrent`	—

Show 16 more fields

Signal	Unit
Batt Fault Pack Over Voltage `VCFRONT_a478_battFaultPackOverVoltage`	—
Battery SM State `VCFRONT_a478_batterySMState`	—
Battery Type `VCFRONT_a478_batteryType` 0 UNKNOWN 1 ATLASBX B24 FLOODED 2 CLARIOS B24 FLOODED 3 CATL LI ION 4 TESLA 16V LI ION 5 TESLA 48V LI ION	—
Bms State `VCFRONT_a478_bmsState`	—
Contactor E Fuse Stable `VCFRONT_a478_contactorEFuseStable`	—
Crash Detected `VCFRONT_a478_crashDetected`	—
Dcdc LV Support Status `VCFRONT_a478_dcdcLVSupportStatus` 0 IDLE 1 ACTIVE 2 FAULTED	—
Factory Mode `VCFRONT_a478_factoryMode`	—
Frunk Open `VCFRONT_a478_frunkOpen`	—
Hvc E Fuse Stable `VCFRONT_a478_hvcEFuseStable`	—
Not Enough Power For Support `VCFRONT_a478_notEnoughPowerForSupport`	—
Pcs E Fuse Stable `VCFRONT_a478_pcsEFuseStable`	—
Service Mode `VCFRONT_a478_serviceMode`	—
Transport Mode `VCFRONT_a478_transportMode`	—
Vcright E Fuse Stable `VCFRONT_a478_vcrightEFuseStable`	—
Vehicle Power State `VCFRONT_a478_vehiclePowerState` 0 OFF 1 CONDITIONING 2 ACCESSORY 3 DRIVE	—

Check other alerts

With Service Mode Plus enabled, open Service Alerts → All. Review the other alerts for clues to the cause of VCFRONT_a478.