VCFRONT_a402 — LV Battery Cannot Support Vehicle
Full alert identifier: VCFRONT_a402_LVBatteryCannotSupportVehicle
Message shown in the car
Electrical system backup power is unavailable Vehicle will consume more energy while idle
Alert description
The vehicle controller has detected a condition where the low voltage (LV) battery is unable to support vehicle electrical systems. The vehicle is likely to shut down if high voltage (HV) battery support for vehicle electrical systems via the power conversion system (PCS) is lost, so the HV system will remain energized to continue supplying electrical power to the vehicle until the alert clears.
Potential impact
The LV battery is unable to support vehicle electrical systems. 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 LV battery is disconnected or showing degraded functionality, the LV battery internal protection transistor (MOSFET) is detected open, or the reverse battery eFuse has tripped (circuit is open).
Clear condition
The vehicle controller no longer detects a condition where the LV battery is unable to support vehicle electrical systems. May include reconnecting or replacing the LV battery, the LV battery internal protection transistor (MOSFET) being detected closed, or reverse battery eFuse no longer tripped (circuit closed again).
Signals to check
Open this alert in Service Mode Plus and review the Payload tab. Use the field names below to identify the values shown by your vehicle.
| Signal | Unit |
|---|---|
LV Battery Temp
VCFRONT_
|
degC |
| Signal | Unit |
|---|---|
MOS Open
VCFRONT_
|
— |
Battery SM State
VCFRONT_
|
— |
Communication Disconnect LV Battery
VCFRONT_
|
— |
Electrical Disconnect LV Battery
VCFRONT_
|
— |
Failure To Precharge Risk
VCFRONT_
|
— |
Frunk Open
VCFRONT_
|
— |
Reverse Battery Fault
VCFRONT_
|
— |
Service Mode
VCFRONT_
|
— |
Check other alerts
With Service Mode Plus enabled, open Service Alerts → All. Review the other alerts for clues to the cause of VCFRONT_a402.