Re: 528e Electrical Problems

[Margot Anderson <kiawah-anderson@xxxxxxxxxxxxxxxx>]

E28 use bullet-style fuses.  These fuses corrode when the fuse box seal
becomes worn/old/compressed which results in poor contacts.  The fuses
generally need to be rotated monthly to keep the contacts clean.  It is
also important that you have a good fuse box cover seal to prevent
moisture getting into the fuse box. 

The problem you describe with your instrument cluster lights leads me to
believe that the contacts are corroded.  However, it could be the large
blue plug that plugs into the back of the instrument binnacle.  The
contacts within this connector are spring-loaded and over time the
spring tension decreases and full contact is lost.  The only way to fix
this is to pull the instrument binnacle out of the car and cut the zip
tie on the end of the blue connector.  You can then remove the blue
shielding from the black core.  Then use a small screwdriver to bend the
contacts back to their original positions so they can again connect
fully to the pins in the instrument binnacle.  Be sure to replace the
blue sheilding back on the black core and zip tie it as it was
originally to prevent shorts in the system. 

The license plate warning light should stay on even after you hit the
reset button.  But if the license plate light comes on without any of
the exterior lights being on, then you have a fault in the system.  Most
likely a short at the rear lights or one of the plugs running through
the car is loose.  As for the check engine light, that is an indication
that the O2 sensor is faulty or has become unplugged from journeying
over snowdrifts.

Rob Anderson
'86 Hartge M535is
M535i SIG & Registry Chief Technical Advisor
www.M535i.org

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