12 42 500 Replacing battery positive lead (between starter, alternator and battery positive terminal)

WARNING: This page is about a different car, the 2010 BMW 135i, 2009 BMW 135i, and 2008 BMW 135i. However, it is still accessible from the selected car via links, so may be relevant.

Necessary preliminary tasks:

Read out fault memory of DME control unit
Switch off ignition
Disconnect battery negative lead . See 61 20 900 DISCONNECTING AND CONNECTING BATTERY NEGATIVE LEAD .
Remove intake air manifold . See 11 61 050 REMOVING AND INSTALLING INTAKE AIR MANIFOLD (N54, N54T) .

Remove protective cap (not shown).

Release screw, remove battery positive lead (1) from battery positive terminal.

Tightening torque 12 42 3AZ, see 12 42 ALTERNATOR LEAD .

Fig 1: Identifying Battery Positive Lead On Battery Positive Terminal

Courtesy of BMW OF NORTH AMERICA, INC.

Remove protective cap and release nut underneath.

Tightening torque 12 42 1AZ, see 12 42 ALTERNATOR LEAD .

Disconnect battery positive lead (1) from alternator.

Fig 2: Identifying Battery Positive Lead On Alternator

Courtesy of BMW OF NORTH AMERICA, INC.

Unlock plug (1) and remove.

Unfasten nut.

Tightening torque 12 42 2AZ, see 12 42 ALTERNATOR LEAD .

Disconnect battery positive lead (2) from starter motor.

Fig 3: Identifying Plug And Battery Positive Lead

Courtesy of BMW OF NORTH AMERICA, INC.

Unclip battery positive lead (1) from holder (2) and remove.

Fig 4: Identifying Battery Positive Lead And Holder

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: Check stored fault messages.
Now clear the fault memory.