General notes

Courtesy of BMW OF NORTH AMERICA, INC.

WARNING: Hybrid cars have an additional high-voltage electrical system which has its own safety regulations to be observed.

Work on live high-voltage components is expressly prohibited. Prior to every operation which involves a high-voltage component, it is essential to disconnect the high-voltage system from the voltage supply and to secure it against unauthorized return to service.

Switch off ignition.
Remove the high-voltage safety connector.
Prevent the high-voltage safety connector from being reinserted.
Switch the ignition on.
Always wait 10 seconds until the "High-voltage system switched off" Check Control message (ID 636) appears in the instrument cluster.

Courtesy of BMW OF NORTH AMERICA, INC.