BMW production started under the Austin license in 1928 in the Eisenbach factory. Their first car was dubbed the Dixi. The first Dixis had a 743 cc four-cylinder engine that produced 15 horsepower, and did a whopping 50 mph. The 1999 BMW 328I has come a long way since the Dixi. Today's BMW is a complex vehicle with a myriad of high-tech computers and automated systems, not to mention security devices. Most of these systems have memories programmed into them. The memory is kept alive with a very small amount of power when the vehicle is not running. Removing the battery without a back up system to keep the memories alive will erase the programming. A tool consisting of a 9-volt battery and a plug is necessary to preserve the memories when the main battery is disconnected. The battery for a BMW is of a specific group because of its location. It is a sealed battery and possesses a vent nipple on the top side. A vent hose from this nipple passes through a hole in the floor below the battery. For this reason, use no other battery, as the lack of venting can cause an explosion or excessive corrosion in the battery well.
Things You'll Need
- Set of wrenches
- Battery backup tool (can be purchased at most auto parts stores)
Plug the battery backup tool into the cigarette lighter (auxiliary power outlet). This is just a small 9-volt battery attached to a plug suitable to plug into this outlet. It will supply just enough power to keep the circuits and memories alive.
Open the trunk and remove the battery cover on the right side of the trunk floor. Remove the battery negative terminal connector with the use of a wrench. Remove the battery positive terminal connector. Loosen and remove the battery hold-down clamp using a wrench. Disconnect the battery vent tube. Lift the battery out of the car.
Install the new battery and tighten the hold down clamp using a wrench. Install the vent tube to the nipple on the top side of the battery and make sure the hose passes through the hole in the floor. Install the positive battery cable connector on the positive terminal on the battery and tighten it with a wrench.
Install the battery negative cable to the negative terminal on the battery and tighten it with a wrench. Re-install the battery cover on the trunk floor. Unplug the battery backup.
Tips & Warnings
- If a battery backup is not available you will need the radio and navigation codes to reactivate them. These codes are in the owner's manual on a credit card. If they are not available, the dealer will supply them with proof of ownership. Also the sunroof, windows, seats and various items will not function properly without reprogramming procedures found in the owner's manual.
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