Always make sure the ignition switch is in the OFF position before disconnecting the battery. Failure to do so may store faults in the control units.
When the battery is disconnected the radio code, on-board computer and clock settings will be lost. The radio code should be obtained before disconnecting the battery or radio. Once the battery has been reconnected, the radio will not function unless the code is keyed in.
When the battery has been disconnected on E36 models, the finger-jam protection on electrically operated windows must be reinitialized. Failure to reinitialize may result in physical injury.