12 42 530 Replacing battery positive lead (between starter motor and alternator) (M54 / M56)

Read fault memory. Switch off ignition.

Observe safety instructions for handling vehicle battery. See 61 00... SAFETY INSTRUCTIONS FOR HANDLING VEHICLE BATTERY

Remove front underbody protection.

Observe instructions for disconnecting and connecting battery. See 12 00... Instructions for disconnecting and connecting battery 

Disconnect battery negative lead from battery and lay to one side.

Remove suction filter housing. See 13 71 000 REMOVE AND INSTALLING INTAKE FILTER HOUSING (M52TU, M54)

Release nut and disconnect battery positive lead (2) from alternator.

Installation: 

Fig 1: Releasing Nut & Disconnect Battery Positive Lead From Alternator

Courtesy of BMW OF NORTH AMERICA, INC.

E46 only: 

Remove reinforcement plate on front axle support. See 51 71 374 REMOVING AND INSTALLING/REPLACING REINFORCEMENT PLATE ON FRONT AXLE SUPPORT

If fitted:

Remove vacuum reservoir for exhaust flap. See 18 10 020 REMOVING AND INSTALLING/REPLACING VACUUM TANK FOR EXHAUST FLAP

Unscrew nut (1).

Installation: 

Disconnect battery positive lead (2) from starter motor.

Remove battery positive lead.

Fig 2: Disconnecting Battery Positive Lead From Starter Motor

Courtesy of BMW OF NORTH AMERICA, INC.

E39 only: 

Release screw connection of battery positive lead (1) (floorpan).

Release nut on starter motor (3).

Installation: 

Detach battery positive lead (1) from holder (2).

Fig 3: Detaching Battery Positive Lead From Holder

Courtesy of BMW OF NORTH AMERICA, INC.

• Read out fault memory of DME control unit
• Check stored faults
• Rectify faults
• Clear fault memory