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

Necessary preliminary work: 

• Read out the fault memory of the DME control unit.
• Switch off ignition.
• Disconnect BATTERY EARTH LEAD .
• Remove right SUSPENSION CROSS-BRACE .
• Remove SOUND INSULATION for bulkhead on left
• Remove left and right INTAKE FILTER HOUSINGS .
• Remove charge air cooler on left and right. See RIGHT CHARGE AIR COOLER and LEFT CHARGE AIR COOLER .
• Remove intake manifold on left and right. See LEFT INTAKE PLENUM and RIGHT INTAKE PLENUM .
• 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 expanding rivets (1) out of cover (2).

Installation note: 

If necessary, replace damaged expanding rivets.

Make sure holders (3) are correctly seated.

Fig 1: Identifying Expanding Rivets, Cover And Holders

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Release screws (1).

Tightening torque 12 90 4AZ .

Release clamp (2).

Remove lid (3) from auxiliary box.

Fig 2: Identifying Screws, Clamp And Lid

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

Installation note: 

Make sure rubber grommets are correctly fitted (watertightness).

Fig 3: Identifying Carrier Plate

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Unclip grommet hold-down device (1).

Release wiring harness (2) from bulkhead.

Unlock connector (3) and remove.

Fig 4: Identifying Grommet Hold-Down Device, Wiring Harness And Connector

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Release screws (1).

Tightening torque 12 90 2AZ .

Remove electronics box cover (2).

Fig 5: Identifying Screws And Electronics Box Cover

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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).

Fig 6: Identifying Connectors, Rubber Grommets And Grommet Hold-Down Device

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Slacken nut (1).

Tightening torque 12 51 1AZ .

Detach earthing cable (2).

Fig 7: Identifying Slacken Nut And Earthing Cable

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Release screw (1).

Tightening torque 12 51 2AZ .

Fig 8: Identifying Screw

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Release screws (1).

Tightening torque 12 51 2AZ .

Release wiring harness (2).

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

Fig 9: Identifying Screws, Wiring Harness And Loom

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Release screw (1).

Tightening torque 12 51 2AZ .

Raise cable duct (2).

Fig 10: Identifying Screw And Cable Duct

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

Cable (3) does not have to be released.

Fig 11: Pulling Off Cable Duct

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Release screws (1).

Tightening torque 12 51 2AZ .

Raise cable duct (2).

Fig 12: Identifying Screws And Cable Duct

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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.

Fig 13: Identifying Screws, Wiring Loom And Harness

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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.

Clear diagnostic fault entries from fault memory.