12 51 100 Replacing wiring harness section for ignition and injectors (N54)

WARNING: This page is about a different car, the 2016 BMW Z4, 2015 BMW Z4, and 2014 BMW Z4. However, it is still accessible from the selected car via links, so may be relevant.

IMPORTANT: Aluminum screws/bolts must be replaced each time they are released.
Aluminum screws/bolts are permitted with and without color coding (blue).
For reliable identification:
Jointing torque and angle of rotation must be observed without fail (risk of damage) .

IMPORTANT: Read and comply with notes on PROTECTION AGAINST ELECTROSTATIC DISCHARGE (ESD PROTECTION) .

Necessary preliminary tasks:

Read out the fault memory of the DME control unit.
Switch off ignition.
Disconnect BATTERY EARTH LEAD .
Remove ACOUSTIC COVER

Release bolts along line (1).

Tightening torque 12 90 1AZ .

Remove electronics box cover.

Fig 1: Identifying Control Unit Bolts (DME)

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Unlock battery positive lead (1), detach and lay to one side.

Release locks (2) in direction of arrows and pull control unit upwards slightly.

Fig 2: Removing Control Unit Locks

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Pull control unit (1) upwards slightly until plug (2) can be released from control unit in direction of arrow.

Unlock plug (2) and detach from control unit (1).

Fig 3: Removing Control Unit Plug Connection

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Unlock and detach all connectors (1) from ignition coil wiring harness in electronics box.

Unclip rubber grommet hold-down device (2) and release ignition coil wiring harness from electronics box.

Installation note:

Make sure rubber grommets are correctly fitted (watertightness).

Fig 4: Identifying Electronics Box And Rubber Grommet Hold Down Devices

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Press in retaining lugs and withdraw lock (1) in direction of arrow from connector housing.

Fig 5: Pressing Connector Lock Retaining Lugs

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Press locking tabs (1) in direction of arrow and pull contact carrier (2) out of housing.

Fig 6: Pressing Contact Carrier Locking Tabs (Long Connector)

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Press locking tab (1) in direction of arrow and pull contact carrier (2) out of housing.

Fig 7: Removing Contact Carrier From Housing

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Unclip cable duct upper section (1) and expose wiring harnesses.

Fig 8: Locating Cable Duct Upper Section Wiring Harness

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Unlock and remove clip (1).

Release nuts (2) and remove ground connections.

Tightening torque 12 90 2AZ .

Unlock all connectors on ignition coils and injectors and detach.

Release wiring harness (3) from clamps and cable straps, feed out and remove.

Replace defective cable straps.

Fig 9: Identifying Injection, Injectors Wiring Harness, Nuts And Clip

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NOTE: Check wiring harness installation arrangement.
Check plug connections for correct fit.
Check stored fault messages.
Delete fault memory.