12 51 001 Replacing wiring harness section for engine (N63)

Necessary preliminary tasks: 

• Read out fault memory of DME control unit
• Switch off ignition
• Clamp off battery negative lead  , see 61 20 900 DISCONNECTING AND CONNECTING BATTERY NEGATIVE LEAD .
• Remove left and right intake filter housings  , see 13 71 030 REMOVING AND INSTALLING/REPLACING BOTH INTAKE FILTER HOUSINGS (N63) .
• Remove intercooler  on left and right, see 17 51 001 REMOVING AND INSTALLING/REPLACING LEFT INTERCOOLER (N63) or 17 51 001 REMOVING AND INSTALLING/REPLACING RIGHT INTERCOOLER (N63)
• Remove intake manifold  on left and right, see 11 61 068 REMOVING AND INSTALLING/REPLACING RIGHT INTAKE MANIFOLD (N63) .
• Partially remove wiring harness  for ignition and injectors, see 12 51 100 Replacing wiring harness section for ignition and injectors (N63) .
• Detach engine oil line  from oil sump, see 17 22 080 REMOVING AND INSTALLING/REPLACING FEED AND RETURN LINES FOR ENGINE OIL COOLER (N63)

Lever out expander rivet.

Remove gasket (1).

Unscrew screws (2).

Feed out partition (3) and remove.

Fig 1: Identifying Feed Out Partition, Gasket And Screw

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Lever out expander rivet.

Release locks in direction of arrow.

Feed out fresh-air duct (1) and remove.

Fig 2: Identifying Fresh-Air Duct

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Open retainers.

Release lock (1) in direction of arrow.

Remove cover (2).

Fig 3: Identifying Lock And Cover

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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.

Fig 4: Identifying Plug Strip

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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).

Fig 5: Identifying Retaining Bar

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Release screw (1).

Tightening torque 12 51 2AZ, see 12 51 ENGINE WIRING HARNESS (N63) .

Fig 6: Identifying Retaining Bar And Screw

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Release screws (1).

Tightening torque 12 51 2AZ, see 12 51 ENGINE WIRING HARNESS (N63) .

Release wiring harness (2).

Release wiring harness (3) and lay to one side.

Fig 7: Releasing Wiring Harness

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Release screw (1).

Tightening torque 12 51 2AZ, see 12 51 ENGINE WIRING HARNESS (N63) .

Raise cable duct (2).

Fig 8: Raising Cable Duct

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Pull off cable duct (1) from cable holder (2) in upward direction.

Cable (3) does not have to be released.

Fig 9: Identifying Cable Duct And Cable Holder

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Release screws (1).

Tightening torque 12 51 2AZ, see 12 51 ENGINE WIRING HARNESS (N63) .

Raise cable duct (2).

Fig 10: Identifying Cable Duct And Screws

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Remove coolant pipe  (1), see 17 00... INSTRUCTIONS FOR WORKING ON COOLING SYSTEM . .

Unfasten screws (2).

Tightening torque 12 51 2AZ, see 12 51 ENGINE WIRING HARNESS (N63) .

Lay wiring harness (4) to one side.

Release wiring harness (3) and lay to one side.

Fig 11: Releasing Wiring Harness

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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.