12 51 001 Replacing wiring harness section for ignition coils on right or left (N74)

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

IMPORTANT: Screw back on all screw points of cable channels without fail ! Some screw points are also ground points . If the wiring harnesses are not correctly screwed tight and secured, this may cause DME malfunction and failure!

Necessary preliminary tasks:

Read out fault code memory of the DME control unit.
Switch off ignition
Disconnect BATTERY NEGATIVE CABLE
Remove charge air cooler on left or right. See RIGHT INTERCOOLER or LEFT INTERCOOLER

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

Release screws (1).

Tightening torque: see 2AZ in 12 90 ELECTRONICS BOX, WIRING HARNESS .

Remove electronics box cover (2).

Fig 1: Identifying Electronics Box Cover Screws

Courtesy of BMW OF NORTH AMERICA, INC.

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

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.

Fig 2: Identifying Control Unit Connectors, Rubber Grommets And Grommet Hold-Down Device

Courtesy of BMW OF NORTH AMERICA, INC.

Installation note:

Make sure grommets are correctly seated (watertightness).

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

Release screw (1).

Tightening torque: see 5AZ in 12 52 ENGINE WIRING HARNESS .

Unfasten screws (2).

Tightening torque: see 5AZ in 12 52 ENGINE WIRING HARNESS .

Unlock all connectors from injectors and ignition coils and detach.

Feed out air wiring harness (3) and remove.

Fig 3: Identifying Feed Out Air Wiring Harness And Screws

Courtesy of BMW OF NORTH AMERICA, INC.

IMPORTANT: Screw back on all screw points of cable channels without fail. Some screw points are also ground points .

Release wiring harness if necessary from existing clips and clamps.

Installation note:

Check wiring harness installation arrangement.

Check plug connections for correct fit.

Check stored fault message.

Delete fault memory.