Saab: SAAB 900S-T16 --1989, voltage fluctuation, digital voltmeter

Question
i HAVE NO H.T. SPARK COMING FROM THE COIL.WHEN I CRANK OVER, THE COIL IS ENERGISED (i HAVE VOLTAGE ON THE BLUE WIRE- NEGATIVE TERMINAL WHICH IS THE WIRE TO THE IGN.AMPLIFIER).
I HAVE CHANGED OVER THE IGN. AMPLIFIER(ONE WHICH WORKS).I HAVE UNCOUPLED THE CRANK POSITION SENSOR CONNECTOR PLUG TO SEE IF IT WAS CORRODED-IT WASN'T-AND TESTED THE SENSOR FOR RESISTANCE BUT CAN NOT GET ANY READING ON THE METER ON ANY COMBINATION OF THE THREE WIRES,IT'S AS IF THE WIRES HAVE BEEN SNIPPED(THERE ARE NO BREAKS IN THE WIRING LEADING TO THE ENGINE REAR)

Answer
Terry:
 To check the Hall Sensor:  Connect a high impedance digital voltmeter to pins 24(+) and 20 (-) on the control unit with the hall sensor connected. Crank the engine...you should see a voltage fluctuation from 0.5 to about 3.0 V. If not, then the hall sensor is bad. Also, you should see + V between pins 4(+0  and 10 (-) on the same control unit connector. If not, the control unit is bad.
  Of course bad or corroded wiring anyway along the line could also be a culprit.
         Hope this helps,
         Jerry