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

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 ESD PROTECTION (ELECTRO STATIC DISCHARGE) .

Necessary preliminary tasks

Read out fault memory of DME control unit
Turn off ignition
Disconnect BATTERY NEGATIVE LEAD
Remove ACOUSTIC COVER

Release bolts along line (1).

Tightening torque 12 90 1AZ .

Remove electronics box cover.

Fig 1: Identifying Electronics Box Cover Mounting Bolts

Courtesy of BMW OF NORTH AMERICA, INC.

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: Opening Locks

Courtesy of BMW OF NORTH AMERICA, INC.

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: Pulling Control Unit Upwards

Courtesy of BMW OF NORTH AMERICA, INC.

Unlock and detach all plugs (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:

Make sure rubber grommets are correctly seated (watertightness).

Fig 4: Identifying Electronic Box With Rubber Grommet Hold Down Device And Plugs

Courtesy of BMW OF NORTH AMERICA, INC.

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

Fig 5: Removing Locks By Pressing Retaining Tabs

Courtesy of BMW OF NORTH AMERICA, INC.

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

Fig 6: Pressing Locking Tab

Courtesy of BMW OF NORTH AMERICA, INC.

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

Fig 7: Pressing Locking Tab

Courtesy of BMW OF NORTH AMERICA, INC.

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

Fig 8: Locating Wiring Harness In Cable Duct Upper Section

Courtesy of BMW OF NORTH AMERICA, INC.

Unlock and remove clip (1).

Release nuts (2) and remove earth connections.

Tightening torque 12 90 2AZ .

Unlock all plugs on ignition coils and injectors and detach.

Release wiring harness (3) from retainers and cable ties, feed out and remove.

Replace defective cable ties.

Fig 9: Identifying Wiring Harness With Clips And Nuts

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: Check wiring harness routing.
Check plug connections for correct seating.
Check stored fault messages.
clear fault memory.