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 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 fault memory of DME control unit
- Turn off ignition
- Follow instructions for disconnecting and connecting battery
Disconnect battery negative 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 plug (1) and remove.
Unlock control unit (2) and raise approx. 5 cm.







Unlock plug on control unit and disconnect.
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.







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







Release screws and remove cable duct (1).

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

Work step
Unlock plug connections on
ignition coils and disconnect
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
Unlock plug on electric coolant
pump and disconnect
Unlock plug on coolant thermostat
and disconnect
Disconnect engine ground connection

NOTE:
Tightening torque 12 52 3AZ.
Replace screw.







NOTE:
Check stored fault messages.
Delete fault memory.