BMW X5: Alternator With Drive

REPLACING ALTERNATOR BELT PULLEY

Special tools required:

• 12 7 110.

Remove and install alternator drive belt.

Depending on alternator type, grip shaft with:

• hexagon socket
• multi-tooth socket or
• Torx socket wrench

Release nut with special tool 12 7 110.

Installation:

Tightening torque, 12 31 2AZ / 12 31 3AZ.

Fig. 30: Identifying Special Tool (12 7 110)

REPLACING ALTERNATOR BELT PULLEY (WITH OVERRUNNING CLUTCH)

Special tools required:

• 12 7 120

Remove and install alternator drive belt.

Grip alternator shaft with:

• internal serration

Release nut with special tools 12 7 120.

Installation:

Tighten to specified torque.

CHECKING ALTERNATOR (BSD)

Necessary preliminary tasks:

• Correct connections on charged battery
• Correct connections on alternator and starter motor
• Good ground connection between engine and body
• Tensioned ribbed V-belt
• Read out DME/DDE fault memory.

NOTE: The alternator with BSD interface can communicate with the engine control unit (DME/DDE).

The alternator can identify various faults.

BSD alternator can be recognized by the plug connection on the alternator.

Connect diagnosis tester.

• Function selection
• Complete vehicle
• Drive
• Voltage and current regulation
• Voltage and current generation
• Alternator
• Follow instruction in diagnostic program

Oscillogram for a fault-free alternator:

Fig. 31: Wave Form Graph - Fault-Free Alternator

Oscillogram for a faulty alternator:

One phase interrupted.

Repair/exchange alternator.

Fig. 32: Wave Form Graph - One Phase Interrupted

Interturn fault.

Repair/exchange alternator.

Fig. 33: Wave Form Graph - Interturn Fault

Open circuit in negative diode.

Repair/exchange alternator.

Fig. 34: Wave Form Graph - Open Circuit In Negative Diode

Short circuit in positive diode.

Repair/exchange alternator.

Fig. 35: Wave Form Graph - Short Circuit In Positive Diode

Open circuit in positive diode.

Repair/exchange alternator.

Fig. 36: Wave Form Graph - Open Circuit In Positive Diode

Open circuit in exciter diode.

Repair/exchange alternator.

Fig. 37: Wave Form Graph - Open Circuit In Exciter Diode

Assemble engine.

Check function of DME/DDE.

REMOVING AND INSTALLING OR REPLACING ALTERNATOR (N52K)

IMPORTANT: Aluminum-magnesium materials.

A magnesium crankcase requires aluminum screws/bolts exclusively.

Aluminum screws/bolts must be replaced each time they are released.

Jointing torque and angle of rotation must be observed without fail (risk of damage).

Necessary preliminary tasks:

• Switch off ignition.
• Disconnect battery negative lead.
• Remove alternator drive belt.

Unlock plug (1) and remove.

Slacken nut (2).

Installation:

Tightening torque 12 31 1AZ.

Release screws and remove alternator (3).

Fig. 38: Identifying Alternator Plug And Nut

Installation:

Replace aluminum screws.

Tightening torque 12 31 1AZ.

Fig. 39: Identifying Alternator Guide Pulley

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