probe the "B" wire (center wire on the plug connector) with the positive wire of a voltmeter, and ground the negative voltmeter wire.
Take 2 readings (Ignition on):
one with the sensor facing a vane on the trigger wheel,
one with the sensor facing "air"
I'm not sure which will be which, but ONE test should show from 9-11 volts, the other test should show about 1/2 volt.
If you get no voltage variation, the sensor may be bad.
If you get no voltage, your not getting power to the sensor.