12 31 020 Removing and installing or replacing alternator (M52, M52TU, S50US, S52, M54, M56)

WARNING: This page is about a different car, the 2003 BMW X5, 2002 BMW X5, and 2001 BMW X5. However, it is still accessible from the selected car via links, so may be relevant.

Necessary Preliminary Tasks:

Read out stored fault messages.
Switch off ignition.
Follow instructions for disconnecting and connecting battery. Refer to 12 00 ... INSTRUCTIONS FOR DISCONNECTING AND CONNECTING BATTERY .
Disconnect and cover battery negative terminal.
Remove suction filter housing. Refer to 13 71 000 REMOVING AND INSTALLING INTAKE FILTER HOUSING (M54) .
Remove fan clutch. Refer to 11 52 020 REMOVING AND INSTALLING/REPLACING FAN CLUTCH (S52 / S54 / M52 / M52TU / M54 / M56) .
Remove alternator drive belt. Refer to 11 28 010 REPLACING ALTERNATOR DRIVE BELT (M52 / S52 / M52TU / M54 / M56) .

If necessary, drain supply tank for power steering pump, remove with holder and place to one side.

NOTE: Lines on supply tank for power steering pump remain connected.

If fitted:

Remove air hose.

Fig 1: Removing Air Hose

Courtesy of BMW OF NORTH AMERICA, INC.

Version 1:

Take off cap on connections.

Disconnect plug connection (1).

Release nut (2) and disconnect battery positive lead.

Tightening torque, refer to 12 31 1AZ in ENGINE ELECTRICAL SYSTEM - TIGHTENING TORQUES .

Fig 2: Disconnecting Plug Connection And Battery Positive Lead (Version 1)

Courtesy of BMW OF NORTH AMERICA, INC.

Version 2:

Unlock and detach plug connection (1).

Release nut (2) and disconnect battery positive lead.

Tightening torque, refer to 12 31 1AZ in ENGINE ELECTRICAL SYSTEM - TIGHTENING TORQUES .

Fig 3: Disconnecting Plug Connection And Battery Positive Lead (Version 2)

Courtesy of BMW OF NORTH AMERICA, INC.

Version Without Idler Pulley:

Release alternator screws in succession while simultaneously gripping alternator firmly.

Remove alternator.

Fig 4: Removing Alternator (Version Without Idler Pulley)

Courtesy of BMW OF NORTH AMERICA, INC.

Version With Idler Pulley:

Remove cover from idler pulley (1).

Release screw and remove idler pulley (1).

Release screw and remove alternator (2).

Fig 5: Releasing Screw And Removing Alternator (Version With Idler Pulley)

Courtesy of BMW OF NORTH AMERICA, INC.

Version With Idler Pulley:

Installation:

Turning lock of tensioning roller must engage in alternator groove.

Fig 6: Turning Lock Of Tensioning Roller Must Engage In Alternator Groove (Version With Idler Pulley)

Courtesy of BMW OF NORTH AMERICA, INC.

Interrogate fault memory of DME control unit.

Now clear the fault memory.