12 51 001 Replacing Wiring Harness Section for Engine

12 51 001 Replacing wiring harness section for engine (N55)







IMPORTANT:
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.
- Disconnect battery earth lead.
- Remove intake plenum.
- Partially detach wiring harness for injectors and ignition coils.
- Remove clean air pipe.
- Remove fan cowl.
- Remove front underbody protection.
- Remove rear underbody protection.
- Remove microfilter housing.







Lever out expanding rivet.
Remove gasket (1).
Unfasten screws (2).
Feed out partition wall (3) and remove.







Lever out expanding rivet.
Release locks in direction of arrow.
Feed out fresh-air duct (1) and remove.







Unlock and pull off all connectors from power distribution module (1).
Do not remove power distribution module.







Release screws and remove retaining bracket (1).
Unlock upper section (2) of partition seal in direction of arrow and remove.
Release grommets (3) for wiring harnesses from lower section of partition seal and from electronics box.

Installation note:
Make sure grommets are is correctly seated (watertightness).







Unlock all connectors (1) from control unit and disconnect.

Installation note:
Make sure plugs are correctly seated (water leaks).







Release screws (1) below cable channel (2).
Replace aluminium screws.
Tightening torque 13 53 10AZ.







Release screws (1).
Tightening torque 12 90 4AZ.
Release cable channel (2).

Installation note:
Reconnect the earth connection.
Replace aluminium screws.

Unlock and disconnect following connectors and lines
Unlock connector on charging pressure sensor and disconnect
Release connector on hot film air mass meter and disconnect
Release connector on intake pressure sensor and disconnect
Release connector on oxygen sensor and disconnect
Unlock connector on monitoring sensor and disconnect
Unlock connector on pressure converter and disconnect
Unlock connector on high-pressure fuel sensor and disconnect
Unlock connector on tank vent valve and disconnect
Unlock connector on starter motor and disconnect
Unlock connector on the knock sensors and disconnect
Unlock connector on oil temperature sensor and disconnect
Unlock connector on fuel low-pressure sensor and disconnect
Release connector on throttle body and disconnect
Release connector on high pressure pump and disconnect
Release connector on alternator and disconnect
Release connector on air conditioning compressor and disconnect
Unlock connector on oil level sensor and disconnect
Unlock connector on crankshaft sensor and disconnect
Unlock connector on heating element for air duct and disconnect
Unlock connector on coolant thermostat and disconnect
Unlock connector on hydraulic valve and disconnect
Unlock connector on the coolant pump and disconnect
Release connector on exhaust turbocharger and disconnect
Unlock connector on both camshaft adjustment solenoid valves and disconnect
Release earth cable on crankcase lower section
Tightening torque 12 90 2AZ.
Release earth cable at rear of cylinder head
Tightening torque 12 90 3AZ.
Unlock connector on intake camshaft pulse sensor and disconnect
Unlock connector on exhaust camshaft pulse sensor and disconnect
Unlock connector on oil pressure switch and disconnect
Unlock connector on servomotor for eccentric shaft and disconnect







Release wiring harness if necessary from existing clips and clamps.
Feed out wiring harness and remove.







Installation note:
Check wiring harness installation arrangement.
Check plug connections for correct fit.
Check stored fault message.
Delete fault memory.