Shortly after killing battery by keeping ignition key on, ABS light came on and a Code 1398 (Crankshaft Position Sensor). Mechanic put in new sensor; Check Engine code appeared again. He's tried several electronic measurement tests on the sensor and it's wiring (as well as the old one and another new one that he got just for testing). Apparently his Mopar book doesn't indicate the expected ohm resistance or voltages that should be expected at certain points. Light still on and driving me crazy. I'm new to Dodge trucks. Also still has not repaired the ABS; just disconnected until we can get the Code 1398 resolved.

Can anyone please help with ideas about this problem???