Battery Isolation Switch: Notes

The Battery Isolation Switch provides the vehicle with separate battery systems for the vehicle circuits and the starting circuit.

When the isolation switch is open, the vehicle circuit battery is the only power source connected to the power distribution center.

When the isolation switch is closed the starter battery is charged and the vehicle circuit battery is boosted by the starter battery.

Modes of the isolation switch:

Fig 1: Identifying Battery Isolation Switch

Courtesy of BMW OF NORTH AMERICA, INC.

• Starting Mode:
  • Normal Starting.
  • Safety Starting.
• Driving Mode.
• Charging Mode.
• Sleep Mode.