I want to watch for a relay closing, and I have a bunch of these old Iris magnetic closure sensors. Seems like there might be a way to solder in a pair of wires and use them for my project... Assuming the magnetic sensor actually closes a contact instead of generating a signal that is interpreted downstream.
Before I started looking up pinouts and doing the work... or randomly shorting pads together... I thought I would ask if anyone had already done this.
No experience with soldering to this device, but alternatively, can you position it close enough to the relay to determine the coil state using it's hall effect sensor? 
That is a good idea but in this case the relay itself is probably out of range. I'm actually connecting wires to a terminal block kind of like this, on the back of a security camera video recorder. (The camera system provides a pretty reliable "did someone drive up?" alarm via sound, email, and switch closure.)
Thanks for figuring out which chip was the sensor. Looks like this family. If that is correct the top is ground, bottom left is power, and bottom right is "output."
https://www.allaboutcircuits.com/electronic-components/datasheet/SM353LT--Honeywell/
And, it looks like the output signal is a small voltage.
So, no easy solder-on-some-wires-and-short-them conversion is possible. Bummer.
Edit: though I guess it depends on the voltage that is on my switch terminals? Maybe an inline resistor can drop the right voltage on that output pin. I'll have to probe the connector and see what's there.
Bingo! Thank you @JBrown. I probably would have started shorting every pin to ground next hoping to get lucky but you nailed it!
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