12 51 100 Replacing wiring harness section for ignition coils (N52K)

WARNING: This page is about a different variant/trim than selected.

IMPORTANT: Aluminium-magnesium materials.

No steel screws/bolts may be used due to the threat of electrochemical corrosion.

A magnesium crankcase requires aluminum screws/bolts exclusively.

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

Aluminum screws/bolts are permitted with and without color coding (blue).

For reliable identification:

Aluminum screws/bolts are not magnetic.

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

IMPORTANT: Read and comply with notes on PROTECTION AGAINST ELECTROSTATIC DISCHARGE (ESD PROTECTION) .

Necessary preliminary tasks:

Read out fault memory of DME control unit
Turn off ignition
Disconnect BATTERY NEGATIVE LEAD
Remove IGNITION COIL COVER

Release bolts along line (1).

Tightening torque 12 90 1AZ .

Remove electronics box cover.

Fig 1: Identifying Electronic Box Cover Mounting Bolts

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Unlock battery positive lead (1), detach and lay to one side.

Release locks (2) in direction of arrows and pull control unit upwards slightly.

Fig 2: Opening Control Unit Locks

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Pull control unit (1) upwards slightly until plug (2) can be released from control unit in direction of arrow.

Unlock plug (2) and detach from control unit (1).

Fig 3: Pulling Control Unit Upwards

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Unlock and detach all plugs (1) from ignition coil wiring harness in electronics box.

Unclip rubber grommet hold-down device (2) and release ignition coil wiring harness from electronics box.

Installation:

Make sure rubber grommets are correctly seated (watertightness).

Fig 4: Identifying Plugs And Rubber Grommet Hold Down Device

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Press in retaining lugs and withdraw lock (1) in direction of arrow from plug housing.

Fig 5: Removing Locks By Pressing Retaining Tabs

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Press locking tabs (1) in direction of arrow and pull contact carrier (2) out of housing.

Fig 6: Pressing Locking Tab

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Press locking tab (1) in direction of arrow and pull contact carrier (2) out of housing.

Fig 7: Pressing Locking Tab

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Unclip cable duct upper section (1) and expose wiring harnesses.

Fig 8: Locating Wiring Harness In Cable Duct Upper Section

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Unlock and remove clip (1).

Unlock all plugs on ignition coils and disconnect.

Unlock plug (2) on Valvetronic servomotor and disconnect.

Release wiring harness from retainers and cable ties (3).

Replace defective cable ties.

Release nuts (4) and remove earth connections.

Tightening torque 12 90 2AZ .

Feed out ignition coil wiring harness and remove.

Fig 9: Identifying Clip, Plug, Cable Ties And Nuts

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Check wiring harness routing.

Check plug connections for correct seating.

Check stored fault messages.

clear fault memory.