12 51 100 Replacing Wiring Harness Section For Ignition Coil

12 51 100 Replacing Wiring Harness Section For Ignition Coil (N52, N52K)







IMPORTANT:
Aluminium-magnesium materials.
No steel screws/bolts may be used due to the threat of electrochemical corrosion.
A magnesium crankcase requires aluminium screws/bolts exclusively.
Aluminium screws/bolts must be replaced each time they are released
Aluminium screws/bolts are permitted with and without colour coding (blue).
For reliable identification:
Aluminium 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 the fault memory of the DME control unit.
- Switch off ignition.
- Follow instructions for disconnecting and connecting battery. Disconnect battery earth lead from battery and lay to one side.
- Remove lower section of microfilter housing.
- Remove acoustic cover
- Remove cylinder head cover.
- Remove front underbody protection.
- N84 only:
Remove pedestrian protection.







Unlock fasteners (1) from below and slide upwards approx. 10 mm.
Unlock locks (2) in direction of arrow.
Remove cover (3).







Unlock connector (1) and remove.
Unlock control unit (2) and raise approx. 5 cm.







Unlock connector on control unit and disconnect.
Unlock tab (1). Pull contact carrier (2) out of housing in the direction of arrow.
Unlock and disconnect all plug connections of ignition coil wiring harness section in electronics box.







Illustration shows cylinder head cover.
Release screws and remove holder (1).
Tightening torque 12 52 1AZ.






N52 only:
Release screws and remove cable channel (1).

Installation note:
Replace aluminium screws.
Tightening torque 12 52 2AZ.







N52K only:
Unlock and remove clip (1).
Unlock all connectors on ignition coils and disconnect.
Unlock connector (2) on Valvetronic servomotor and disconnect.
Release wiring harness from clamps and cable straps (3).
Replace defective cable straps.
Release nuts (4) and remove ground connections.
Feed out ignition coil wiring harness and remove.

Work step Note

Unlock plug connections on ignition
coils and disconnect
Unlock connector on eccentric shaft
sensor and disconnect
Unlock connector of servomotor for
eccentric shaft and disconnect
Unlock connector on both solenoid valves
and disconnect
Unlock connector on inlet and exhaust
camshaft sensors and disconnect
Unlock connector on air conditioning
compressor and disconnect
Unlock connector on oil pressure switch
and disconnect
Unlock connector on coolant temperature
sensor and disconnect
Disconnect connector strip from fuel
injection pipe
Unlock connector on electric coolant
pump and disconnect
Unlock connector on coolant thermostat
and disconnect
Disconnect engine ground connection Tightening torque 12 52 3AZ. Replace screw.







NOTE:
Check stored fault messages.
Delete fault memory.