Interior light door sensors

["Anthony Sarkis" <iosystems@domain.elided>]

For anyone who is interested, I have managed to fix the door lock sensors
that activate the interior cabin lights and the ARC.

Background: The interior cabin lights would not come on when the front doors
are opened in my Alfa 90 (this would apply to 75/milanos), and the ARC would
not register that the doors are open.

I pulled out the front door locks and the sensors are embeded into the
mechanism. But the mechanism can be cracked open by bending some locking
tabs, to reveal a reed switch (a switch that is activated by the proximity
of a magnet).
When the door is open, a metal plate slides between the magnet and reed
switch, which becomes open circuit. When the door shuts, the plate slides
away and the reed switch is close circuit.

The reed switch looks OEM, and is covered in molded plastic to fit properly
in the door lock mechanism. We need this plastic molding because it locates
the reed switch in the lock. If you grind/melt the plastic top, you can
expose the reed switch, and hence be able to replace it. I had to use a
soldering iron, as I don't have a dremel like tool (I am interested in
purchasing a dremel tool, if anyone in the US can arrange one for me to ship
to Australia :).
Any further explantions from here on will require picture/diagrams.
Hopefully if there is enough interest, I could be persuaded to do something
and put it on Tony Lupton's Alfa 90 web site (hey tony...). The orientation
of the reed switch is critical, and it works best to one side of the magnet
(long side of the reed closest to the magnet)

Expose enough wire in the plastic to be able to solder the reed switch.After
the switch is place you might want to cover the "trench you dug" with
silicon or glue (making sure that everything is flush with the original
plastic level, as the metal silder plate in the lock slides very close to
the reed switch casing).

Put all back together in reverse order (I love this workshop manual talk)
and test the door lock with a continuity checker (or plug back into the door
and use the ARC/interior cabin light to check operations) before bending the
locking tabs of the door lock back in and bolting back into the door.

Any questions? let me know.

Later, Anthony.

PS: I want a dremel tool(preferably with the flex shaft).

Anthony Sarkis
Telstra Multimedia, Sydney
email: iosystems@domain.elided

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