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 tasks:
- Read out fault memory of DME control unit
- Switch off ignition
- Clamp off battery negative lead
- Remove left and right intake filter housings.
- Remove intercooler on left and right
- Remove intake manifold on left and right
- Partially remove wiring harness for ignition and injectors.
- Detach engine oil line from oil sump







Lever out expander rivet.
Remove gasket (1).
Unscrew screws (2).
Feed out partition (3) and remove.







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







Open retainers.
Release lock (1) in direction of arrow.
Remove cover (2).







Unlock all plugs (1) of DME control unit and disconnect.
Unlock plug on electronics box fan and disconnect.
Unlock all plugs on plug strip (2) and detach.
Unlock plug strip (2) and remove towards top.
Unlock all plugs on plug strip (3) and detach.
Unlock plug strip (3) and remove towards top.

Installation:
When replacing wiring harness, modify plug strips (2) and (3) if necessary.







Release screws and remove retaining bar (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:
Make sure grommets are is correctly seated (watertightness).







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







Release screws (1).
Tightening torque 12 51 2AZ.
Release wiring harness (2).
Release wiring harness (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).







Remove coolant pipe (1).
Unfasten screws (2).
Tightening torque 12 51 2AZ.
Lay wiring harness (4) to one side.
Release wiring harness (3) and lay to one side.

Unlock and disconnect following plugs and leads

Unlock plug on crankshaft sensor and disconnect
Transmission wiring harness

Unlock plug on transmission and disconnect
Transmission wiring harness

Unlock plug on oil pressure sensor and disconnect
Transmission wiring harness

Unlock plug on right inlet camshaft pulse generator and disconnect
Transmission wiring harness

Unlock plug on right exhaust camshaft pulse generator and disconnect
Transmission wiring harness

Unlock plug on starter and disconnect
Transmission wiring harness

Unlock plug on oil level sensor and disconnect
Transmission wiring harness

Disconnect ground cable. Tightening torque 12 51 1AZ.
Transmission wiring harness

Unlock plug on left and right air mass sensors and disconnect
Engine wiring harness

Unlock plug on left and right high-pressure fuel pumps and disconnect
Engine wiring harness

Unlock plug on left and right control sensors and disconnect
Engine wiring harness

Unlock plug on left and right monitor sensors and disconnect
Engine wiring harness

Unlock plug on left and right high-pressure fuel sensors and disconnect
Engine wiring harness

Unlock plug on left and right intake air pressure sensors and disconnect
Engine wiring harness

Unlock plug on A/C compressor and disconnect
Engine wiring harness

Unlock plug on left and right knock sensors and disconnect
Engine wiring harness

Unlock plug on left and right charge-air pressure sensors and disconnect
Engine wiring harness

Unlock plug on coolant temperature sensor to coolant pump and disconnect
Engine wiring harness

Unlock plug on coolant thermostat and disconnect
Engine wiring harness

Unlock plug on pressure transducers and disconnect
Engine wiring harness

Unlock plug on left and right throttle valve assemblies and disconnect
Engine wiring harness

Unlock plugs on solenoid valves for camshaft adjustment on left and right and disconnect
Engine wiring harness

Unlock plug on turbocharger coolant pump and disconnect
Engine wiring harness

Unlock plug on turbochargers and disconnect
Engine wiring harness

Unlock plug on alternator and disconnect
Engine wiring harness

Unlock plug on right inlet camshaft pulse generator and disconnect
Engine wiring harness

Unlock plug on right exhaust camshaft pulse generator and disconnect
Engine wiring harness

Unlock plug on low-pressure fuel sensor and disconnect
Engine wiring harness

Unlock plug on coolant pump for intercooler and disconnect
Engine wiring harness







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







Installation:
Check wiring harness routing.
Check plug connections for correct seating.
Check stored fault message.
Now clear the fault memory.