I believe it is just a VRM type sensor which is a coil of wire wrapped around a magnet (basically). So if you put an ohm meter on it you should read maybe 100 or 200 ohms? I just put a meter on a VRM sensor we had laying around and it read 260 ohms but it is a little bigger and made for sensing teeth on a gear box but should be similar. Obviously if you read "OL" then there is a wire broken. If the break is at the entry point of the wire then you should be able to wiggle the wire and get intermittent contact. Otherwise the break is inside although I don't see how it could break. I would think a junk yard would be a decent source.

Edit: Well I just looked at a picture of one for a 84 500 SEL (I don't know if that is the same). Anyway it looks pretty strange. It doesn't look like any VRM I have ever seen with the little thingy sticking out the end. Does it seem like there is a magnet in it?

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra