12 63 520 Replacing main relay (M54 / S54)

WARNING: This page is about a different car, the 2002 BMW Z3 and 2001 BMW Z3. However, it is still accessible from the selected car via links, so may be relevant.

Switch off ignition.

Connect DIS Tester.

Release screw connection of electronics box (1).

Remove electronics box (1).

Fig 1: Removing Electronics Box Screws

Courtesy of BMW OF NORTH AMERICA, INC.

Arrangement:

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

Fig 2: Identifying Engine Fuses And Main Relay Of Digital Motor Electronics

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.