12 51 100 Replacing Wiring Harness Section For Ignition Coil (N54)

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IMPORTANT:

Aluminum-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.

The end faces of aluminum screws/bolts are painted blue for the purposes of 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 damage (ESD protection). (See 61 35 ... NOTES ON ESD PROTECTION (ELECTRO STATIC DISCHARGE) and 61 35 ... NOTES ON ESD PROTECTION (ELECTRO STATIC DISCHARGE) )

Necessary preliminary tasks:

Read out fault memory of DME control unit
Switch off ignition
Disconnect battery negative lead (See 61 20 900 DISCONNECTING AND CONNECTING BATTERY NEGATIVE LEAD and/or 61 20 900 DISCONNECTING AND CONNECTING BATTERY NEGATIVE LEAD )
Remove acoustic cover (See 11 00 REMOVING AND INSTALLING/REPLACING ACOUSTIC COVER (N52) )
Remove intake duct (See 13 REMOVING INTAKE DUCT (N52/N52K/N51/N53) )

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

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Unlock plug (1) and remove.

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

Fig 2: Identifying Control Unit

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

Fig 3: Pressing Locking Tab (1 Of 2)

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

Fig 4: Pressing Locking Tab (2 Of 2)

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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 duct (1).

Installation:

Replace aluminum screws.

Tightening torque 12 52 2AZ, see ENGINE ELECTRICAL SYSTEM -- TORQUE SPECIFICATIONS -- TWIN TURBO .

Fig 6: Identifying Cable Duct

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WORK STEP TABLE

Work step	Note:
Disconnect positive lead at jump-start connection point	-
Unlock plug connections on ignition coils and disconnect	-
Unlock plug on injectors and disconnect	-
Release ground connections	-
Unlock plug on pressure transducers and disconnect	-
Unlock plug on both solenoid valves and disconnect	-
Unlock plug on inlet and exhaust camshaft sensors and disconnect	-
Unlock plug for high-pressure sensor and disconnect	-
Unlock plug on oil pressure switch and disconnect	-
Unlock plug on coolant temperature sensor and disconnect	-
Remove front underbody protection (See 51 47 490 REMOVING AND INSTALLING/REPLACING FRONT ASSEMBLY UNDERSIDE PROTECTION and/or 51 47 490 REMOVING AND INSTALLING/REPLACING FRONT ASSEMBLY UNDERSIDE PROTECTION )	-
Unlock plug on electric coolant pump and disconnect	-
Unlock plug on coolant thermostat and disconnect	-
Release ground connection on engine next to coolant pump	Tightening torque 12 52 3AZ. Replace screw. See ENGINE ELECTRICAL SYSTEM - TIGHTENING TORQUES - COUPE .

NOTE:

Check stored fault messages.

Now clear the fault memory.