12 51 100 Replacing Wiring Harness Section For Ignition Coil (N51, N52K)

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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.

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 damage (ESD protection). See 61 35... NOTES ON ESD PROTECTION (ELECTRO STATIC DISCHARGE) (CONVERTIBLE) or 61 35... NOTES ON ESD PROTECTION (ELECTRO STATIC DISCHARGE) (COUPE) .

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 (CONVERTIBLE) or 61 20 900 DISCONNECTING AND CONNECTING BATTERY NEGATIVE LEAD (COUPE) .
Remove ignition coil cover . See 11 00 REMOVING AND INSTALLING/REPLACING ACOUSTIC COVER (N52/N52K) .
Remove intake duct . See 13 REMOVING INTAKE DUCT (N52) .

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

Unlock locks (2) in direction of arrow.

Remove cover (3).

Fig 1: Unlocking Locks In Direction Of Arrow

Courtesy of BMW OF NORTH AMERICA, INC.

Unlock plug (1) and remove.

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

Release grommet (3) from electronics box.

Installation:

Make sure grommet (3) is correctly seated in electronics box (watertightness).

Fig 2: Unlock Plug & Control Unit

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Unlock tab (1). Pull contact carrier (2) in direction of arrow out of housing.

Unlock and disconnect all plug connections of ignition coil wiring harness section in electronics box.

Fig 3: Pulling Contact Carrier

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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: Pressing Locking Tab

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WORK STEP TABLE

Work step	Note:
Disconnect positive lead from battery positive terminal	-
Disconnect ground cables	-
Unlock plug connections on ignition coils and disconnect	-
Unlock cable duct on cylinder head cover and detach	-
Unlock plug on eccentric shaft sensor and disconnect	-
Unlock plug on positioning motor for eccentric shaft and disconnect	-
Unlock plug on both solenoid valves and disconnect	-
Unlock plug on inlet and exhaust camshaft sensors and disconnect	-
Unlock plug on air-conditioning compressor and disconnect	-
Unlock plug on oil pressure switch and disconnect	-
Unlock plug on coolant temperature sensor and disconnect	-
Disconnect connector strip from fuel rail	-
Remove front underbody protection	-
Unlock plug on electric coolant pump and disconnect	-
Unlock plug on coolant thermostat and disconnect	-
Disconnect engine ground connection	Tightening torque, see 12 52 3AZ in 12 52 PLUG CONNECTIONS, TERMINALS, LOOSE PARTS . Replace screw.

NOTE:

Check stored fault messages.

Now clear the fault memory.