The days of passive sensors in cars are over. Have been over for a long time, because this is the ABS wheel speed sensor used in 2004+ T5 VW transporters, and it has a bunch of electronics inside (I’m guessing similar to this device).
It’s a two-pin device, and if you try to measure the resistance, you will get ~4.5 megohm. A component tester will tell you it’s two back-to-back diodes, one with Vf = 0.7V the other around 3V.
So, connect 12V to pin 1 (the flat side of the connector) via a 1 kohm resistor, and 0V to pin 2. Multimeter to pins 1 and 2. You will see the output voltage (i.e. the current through the resistor) change when you wave a magnet around the business end of the sensor.
In my case, the sensor was not the problem.
This was the problem. This “fix” (being a stiff wire rammed down into the connector to make contact with the sensor pin, all wrapped up in insulation tape) didn’t last long, I guess, so they resorted to Plan B.
This… was their Plan B. Remove the cluster, disassemble the cluster, cover the warning lights (ABS and Traction Control) with funny putty, and re-assemble*. A two-hour job, rather than the half hour it took me to replace the connector end with a good one from the spare, with good solder joints and heat shrink tubing. Doing the job right. What a novel concept.
And of course it took me more than two hours to sort out the cluster. Getting the funny putty out is much more work than putting it in.
* My brother tells the story of the fellow who took his car in because fifth gear did not work. Guy fixed it for R100 in parts and half an hour labour — he replaced the gear shift knob with one from a four-speed.