so you've done this ?

Crank Sensor Checking - info courtesy of Simon @ SECS
1) Ensure ignition is OFF.
2) Remove rear of ecu plug cover and insert plug back into ecu.
3) Turn ignition back on (do not start engine)
4) CRANK SENSOR: Check resistance between pins 3 and 4 between 300 and 1200 ohms.
5) CRANK SENSOR: Check AC voltage on pins 3 and 4 while cranking engine - should be at least 2V.