12 51 001 Replacing Wiring Harness Section For Engine

12 51 001 Replacing Wiring Harness Section For Engine (N63)







IMPORTANT: Read and comply with notes on protection against electrostatic damage (ESD protection).







Necessary preliminary work:
- Read out the fault memory of the DME control unit.
- Switch off ignition.
- Disconnect battery earth lead.
- Remove right suspension crossbrace.
- Remove sound insulation for bulkhead on left
- Remove left and right intake filter housings.
- Remove charge air cooler on left and right.
- Remove intake manifold on left and right.
- Partially remove wiring harness for ignition and injectors.
- Detach engine oil pipe from oil sump







Picture shows the left side, the procedure for the right side is identical.
Lever expander rivets (1) out of cover (2).

Installation note:
If necessary, replace damaged expanding rivets.
Make sure holders (3) are correctly seated.







Release screws (1).
Tightening torque 12 90 4AZ.
Release retainer (2).
Remove cover (3) from supplementary box.







Disconnect all plugs from carrier plate (1) and release from supplementary electronics box.

Installation note:
Make sure rubber grommets are correctly fitted (watertightness).







Unclip grommet hold-down device (1).
Release wiring harness (2) from bulkhead.
Unlock connector (3) and remove.







Release screws (1).
Tightening torque 12 90 2AZ.
Remove electronics box cover (2).







Unlock all connectors (1) from control unit and disconnect.
Unclip grommet hold-down device (2) and remove.
Detach rubber grommets (3) from electronics box. Place wiring harnesses to the side.

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







Slacken nut (1).
Tightening torque 12 51 1AZ.
Detach earthing cable (2).







Release screw (1).
Tightening torque 12 51 2AZ.







Release screws (1).
Tightening torque 12 51 2AZ.
Release wiring harness (2).
Release wiring loom (3) and lay to one side.







Release screw (1).
Tightening torque 12 51 2AZ.
Raise cable duct (2).







Pull off cable duct (1) from cable holder (2) in upward direction.
Cable (3) does not have to be released.







Release screws (1).
Tightening torque 12 51 2AZ.
Raise cable duct (2).







Release screws (1).
Tightening torque 12 51 2AZ.
Release screw (2).
Lay wiring loom (4) to one side.
Release wiring harness (3) and lay to one side.

Unlock and disconnect following connectors and lines
Unlock connector on crankshaft sensor and disconnect
Release connector on transmission and disconnect
Release connector on oil pressure sensor and disconnect
Unlock plug on right inlet camshaft pulse generator and disconnect
Unlock plug on right exhaust camshaft pulse generator and disconnect
Unlock connector on starter motor and disconnect
Unlock connector on oil level sensor and disconnect
Unlock connector on left and right hot film air mass meter and remove
Unlock connector on left and right high pressure pumps and disconnect
Unlock connector on left and right control sensors and disconnect
Unlock plug on left and right monitor sensors and disconnect
Unlock plug on left and right high-pressure fuel sensors and disconnect
Unlock plug on left and right intake air pressure sensors and disconnect
Release connector on air conditioning compressor and disconnect
Unlock plug on left and right knock sensors and disconnect
Unlock plug on left and right charge-air pressure sensors and disconnect
Unlock plug on coolant temperature sensor to coolant pump and disconnect
Unlock connector on coolant thermostat and disconnect
Unlock plug on left and right throttle valve assemblies and disconnect
Unlock plugs on solenoid valves for camshaft adjustment on left and right and disconnect
Unlock plug on turbocharger coolant pump and disconnect
Unlock connector on the exhaust turbochargers and disconnect
Release connector on alternator and disconnect
Unlock plug on left inlet camshaft pulse generator and disconnect
Unlock plug on left exhaust camshaft pulse generator and disconnect
Unlock plug on low-pressure fuel sensor and disconnect
Unlock plug on coolant pump for charge air cooler 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.