12 51 100 Replacing wiring harness section for ignition coil (N54, N54T)

IMPORTANT: 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:
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 the fault memory of the DME control unit.
Switch off ignition.
Disconnect BATTERY EARTH LEAD .
Remove ignition coil cover. See 11 00 REMOVING AND INSTALLING/REPLACING IGNITION COIL COVER (N54, N54T) .
Remove intake port. See 13..... REMOVING INTAKE PORT (N54, N54T) .

Unlock fasteners (1) from below and slide upwards approx. 10 mm.

Unlock locks (2) in direction of arrow.

Remove cover (3).

Fig 1: Removing Cover Fasteners

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Unlock connector (1) and remove.

Unlock control unit (2) and raise approx. 5 cm.

Fig 2: Identifying Control Unit And Connector

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

Fig 3: Pulling Contact Carrier Out Of Housing

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

Fig 4: Pressing Locking Tabs

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

Fig 5: Pulling Contact Carrier Out Of Housing

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Release screws and remove cable channel (1).

Installation note:

Replace aluminum screws.

Tightening torque: 12 52 2AZ .

Fig 6: Identifying Cover Screws

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Work step	Note
Detach positive battery cable from positive battery connection point.
Unlock plug connections on ignition coils and disconnect
Unlock and pull off connector on injectors.
Release the ground connections.
Unlock plug on pressure transducers and disconnect
Unlock connector on both solenoid valves and disconnect
Unlock connector on inlet and exhaust camshaft sensors and disconnect
Release connector for high pressure sensor and remove.
Unlock connector on oil pressure switch and disconnect
Unlock connector on coolant temperature sensor and disconnect
Remove front underbody protection . See 51 47 490 REMOVING AND INSTALLING/REPLACING FRONT UNDERBODY PROTECTION or 51 47 490 REMOVING AND INSTALLING/REPLACING FRONT UNDERBODY PROTECTION (AWD)
Unlock connector on electric coolant pump and disconnect
Unlock connector on coolant thermostat and disconnect
Disconnect engine ground connection next to the coolant pump	Tightening torque: 12 52 3AZ , replace screw.

NOTE: Check stored fault messages.

Delete fault memory.