12 51 001 Replacing wiring harness section for engine (N52K, N51)

Necessary preliminary tasks: 

• Read out fault memory of DME control unit
• Switch off ignition
• Disconnect Battery Negative Lead
• Remove Intake Air Manifold

Unlock fasteners (1) from below and slide upwards approx. 10 mm.

Unlock locks (2) in direction of arrow.

Remove cover (3).

Fig 1: Identifying Fasteners, Locks, Cover And Removal Direction

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Unlock plug on control unit and disconnect.

Release grommet (2) from electronics box.

Installation: 

Make sure grommet (2) is correctly seated in housing (watertightness).

Unlock control unit (3) and raise slightly.

Fig 2: Identifying Plug, Grommet And Control Unit

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Unlock plugs (1) using slide in direction of arrow and disconnect.

Fig 3: Identifying Plugs And Removal Direction

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Long plug:

Unlock plug on control unit and disconnect.

Unlock tab (1), pull contact carrier (2) in direction of arrow out of housing.

Fig 4: Identifying Tab, Contact Carrier And Removal Direction

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Short plug:

Unlock slide (2) in bore holes (1) and pull out of housing.

Unlock tab (3), pull contact carrier (4) in direction of arrow out of housing.

Unlock and disconnect all plug connections of engine wiring harness section in electronics box.

Fig 5: Identifying Slide, Bore Holes, Tab, Contact Carrier And Removal Direction

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Now clear the fault memory.