BMW X3 Service & Repair Manual: Notes for disconnecting and connecting battery

Observe SAFETY INFORMATIONS FOR HANDLING VEHICLE BATTERY .

Before disconnecting battery:

Turn off the ignition and other electrical loads/consumers to prevent sparking when reconnecting.

NOTE: If the ignition is not turned off when the battery is disconnected, fault memories may be set in some control units.

IMPORTANT:

• There is a danger of mixing up battery cables: If the battery positive and negative leads are the same color and you are in doubt, follow the polarity to the battery, then mark and cover the leads.
• The on-board computer and clock may lose your data.

General notes on disconnecting battery:

• Do not disconnect battery leads and leads from alternator and starter motor while engine is running.
• Disconnect terminal of BATTERY EARTH LEAD from the battery. Cover battery negative terminal(s) and secure.
• Disconnect both battery earth leads in version with auxiliary battery. Cover battery negative terminal(s) and secure.
• When work is carried out on the electrical system, faults may be caused in the fault memories of some control units when the battery is connected.
• When installing battery terminal

Only lead AGM battery:

• On vehicles with IBS at negative battery terminal:
  Do not under any circumstances pull/lever off pole shoes by force.
  Do not under any circumstances release socket-head cap screw of IBS.

After connecting battery:

IMPORTANT: The scope of application of some systems may be restricted after an open circuit.

Personal Profiles may also be lost.

Settings or activations must be carried out, depending on the equipment specification.

For example:

• Activate slide/tilt sunroof.
• Activate power window .

Refer to the diagnosis system for further vehicle-specific information.