12 42 500 Replacing Battery Positive Lead (Between Starter, Alternator And Battery Positive Terminal)

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2013 BMW 128i, 2012 BMW 128i, 2011 BMW 128i, 2010 BMW 128i, and 2009 BMW 128i. 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 (CONVERTIBLE) or 61 20 900 DISCONNECTING AND CONNECTING BATTERY NEGATIVE LEAD (COUPE) .
Follow instructions for disconnecting and connecting battery . See 12 00... Instructions For Disconnecting And Connecting Battery .

Remove intake air manifold . See 11 61 050 REMOVING AND INSTALLING INTAKE AIR MANIFOLD (N51) .

Remove protective cap (not shown).

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

Tightening torque, see 12 42 1AZ in STARTER LEAD .

Fig 1: Identifying Battery Positive Lead

G04751340

Courtesy of BMW OF NORTH AMERICA, INC.

Release nut and remove battery positive lead (1) from alternator.

Tightening torque, see 12 31 1AZ in ALTERNATOR WITH DRIVE AND MOUNT .

Fig 2: Locating Nut For Battery Positive Lead

G04751341

Courtesy of BMW OF NORTH AMERICA, INC.

Unlock plug (1) and remove.

Unfasten nut.

Tightening torque, see 12 41 3AZ in 12 41 STARTER MOTOR WITH MOUNTING .

Detach battery positive lead (2) from starter motor and remove.

Fig 3: Identifying Plug & Nut

G04751335

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: Check stored fault messages.

Now clear the fault memory.