12 51 100 Replacing wiring harness section for ignition and injectors (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 BOTH INTAKE FILTER HOUSINGS (N63) .
• Remove microfilter housing  , see 64 31 081 REMOVING AND INSTALLING/REPLACING MICROFILTER HOUSING .
• Partially release wiring harness  for engine, see 12 51 001 Replacing wiring harness section for engine (N63) .
• Remove coolant pipe  from cylinder head cover on left, see 17 00... INSTRUCTIONS FOR WORKING ON COOLING SYSTEM .
• Remove fuel feed line  , see 13 53 332 REMOVING AND INSTALLING/REPLACING FEED LINE (N63) .

Lever out expander rivet.

Remove gasket (1).

Unscrew screws (2).

Feed out partition (3) and remove.

Fig 1: Identifying Lever Out Expander Rivet, Gasket And Screws

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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 Cover And Lock

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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 correctly seated (watertightness).

Fig 5: Removing Retaining Bar

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Release clamps (1) and (2).

Replace clamps (2).

Detach both charge-air ducts (3) and remove.

Check gaskets on turbocharger, replacing if necessary.

Fig 6: Identifying Charge-Air Ducts And Clamps

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Picture shows the left side, the procedure for the right side is identical.

Detach hoses (1) from clean-air pipe.

Release screw (2).

Tightening torque 13 71 1AZ, see 13 71 AIR INTAKE DUCT .

Detach clean-air pipe (3) in direction of travel from turbocharger.

Check seal on clean-air pipe, replacing if necessary.

Fig 7: Checking Seal On Clean-Air Pipe

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Release bolts (1).

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

Unlock plugs on injectors and ignition coils and detach.

Release wiring harness (2).

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

Fig 8: 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 9: Identifying Cable Duct And Screw

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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 10: Pulling Cable Duct

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Release bolts (1).

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

Raise cable duct (2).

Fig 11: Raising Cable Duct

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

Release screws (2).

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

Unlock plugs on injectors and ignition coils and detach.

Lay wiring harness (4) to one side.

Feed out air wiring harness (3) and remove.

Fig 12: Laying Wiring Harness

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