12 63 520 Replacing Main Relay

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2006 BMW M3, 2005 BMW M3, 2004 BMW M3, 2003 BMW M3, and 2002 BMW M3. However, it is still accessible from the selected car via links, so may be relevant.

Switch off ignition.

Connect DIS Tester.

Release screws (1).

Remove electronics box cover.

Fig 1: Identifying Electronics Box Cover

Courtesy of BMW OF NORTH AMERICA, INC.

Installation:

Correctly install wiring harness with grommet in electronics box cover (water tightness).

Hook cover (3) into hinges of underside of electronics box (1). Then correctly install upper stop (2) above hinges on underside of electronics box.

Fig 2: Locating Hinges Of Underside Of Electronics Box

Courtesy of BMW OF NORTH AMERICA, INC.

Arrangement:

Main relay of Digital Motor Electronics.
Engine fuses of Digital Motor Electronics.

Fig 3: Identifying Main Relay And Engine Fuses Of DME

Courtesy of BMW OF NORTH AMERICA, INC.

Notes On Troubleshooting:

If the starter motor cranks the engine during the starting sequence but the engine fails to fire, then:

Check engine fuses.
If fuses are blown, replace them completely with fuse holder.
Find out why fuses have blown.

Continue troubleshooting as per DIS instructions.