Jump Starting

CAUTION: Jump starting should be avoided if possible, voltage surges over 15 volts are harmful to many of the electronics in the vehicle. Replace or charge the battery properly whenever possible.

Most BMWs have their batteries in the trunk/cargo area or under the rear seat. Having the batteries out of the hot engine compartment helps to extend battery life. The rear location also helps in vehicle weight distribution and can act as a harmonic dampener.

If jump starting is the only alternative it should be conducted at the jump starting terminals in the engine compartment.

A review of proper jump starting is as follows:

Fig 1: Identifying Jump Starting Location (E36)

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Fig 2: Identifying Jump Starting Location (Typical Of E38, E39, E52 And E53)

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Carefully observe location and polarity of terminals.

Positive cable to support car.
Positive cable to car needing jump.
Negative cable to CHASSIS GROUND on support vehicle first then to the vehicle needing jump.

Fig 3: Locating Bolt
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Before disconnecting the jumper cables apply a load to the electrical system by: turning on the lights, rear window defroster, and blower on maximum. This will minimize risk of voltage surge when the cables are disconnected.
Remove cables in the reverse order.