12 63 520 Replacing main relay

WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2005 BMW 325xi, 2005 BMW 325i, 2005 BMW 325Ci, 2004 BMW 325xi, and 2004 BMW 325i. 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: Removing 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: Hooking Cover Into Hinges Of Underside Of Electronics Box

Courtesy of BMW OF NORTH AMERICA, INC.

Arrangement:

Fig 3: Identifying Main Relay Of Digital Motor Electronics

Courtesy of BMW OF NORTH AMERICA, INC.

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

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.