12 31 020 Removing and installing or replacing alternator (M54)

Necessary preliminary tasks:

Check stored fault messages.
Switch off ignition.
Observe instructions for disconnecting and connecting battery.
Disconnect battery ground wire and mask it.
Remove suction filter housing. See 13 71 000 REMOVING AND INSTALLING INTAKE FILTER HOUSING .
Remove alternator drive belt. See GENERATOR DRIVE BELT .

Unlock and detach plug connection (1).

Release nut (2) and remove battery positive lead.

Tightening torque, see 12 31 1AZ and 12 12 1AZ in ENGINE ELECTRICAL SYSTEM - TIGHTENING TORQUES .

Fig 1: Removing Battery Positive Lead

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Remove cover from idler pulley (1).

Release screw and remove idler pulley (1).

Release screw and remove alternator (2).

Fig 2: Removing Alternator

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Installation:

Turning lock of tensioning roller must engage in alternator groove.

Fig 3: Locating Lock Of Tensioning Roller

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NOTE: Read out fault memory of DME control unit.

Now clear the fault memory.