Chrysler Repair: 94 NY intermittent no start/shut down, crankshaft sensor, voltage pulses

Question
Wife's car problem. Naturally symptoms quit upon my arrival. Problem 1: no start(lunchtime michigan)- all elec. components work, but no start when key is turned.Will start when I arrive, every time, 5 in a row at least.Test drive & start& start& start...= all systems normal(runs great). Prob 2: shuts off while driving, will restart after 1 to 5 attempts. Replaced battery(old battery-loose cap 1 low cell), key codes: 11, 12(naturally), 55. Noted all PNRDL lights on@ same time- actuated shifter thru all positions repeatedly problem quit. Headed to local parts dealer to start the guessing game.Any tips appreciated as I have read your postings and am very! impressed. Thanx in advance.
  MJP

Answer
Hi Mike,
Flattery will get you everything!
The 11 code is the key to this situation. That one means that the crankshaft sensor signal is not reaching the powertrain control module, most likely because the hall effect-based sensor itself is failing. This sort of symptomology is diagnostic for that problem. When it warms up it fails, then cools down and works again. Or it will fail intermittantly when cold. I assume that by no start you don't mean the starter motor won't crank over, rather that the engine will not come to life.
The sensor is mounted on the bell housing at the interface with the transmisssion because it 'looks' at cut-out openings in the circumference of the torque converter drive plate to get its information. You might want to check its 3-wire plug and verify that with the ignition switch 'on' the orange wire has 8V on it measured with the plug removed,  and that the light blue/dark blue wire (which you would need to probe with a fine needle) when the plug is reconnected to the sensor AND the engine won't start is indeed showing no voltage pulses (normally would be varying from 0.3 to 5.0V which it will do when the sensor is operational and you tweek the starter motor with the ignition switch so as to rotate the engine briefly at low rpm so the pulses will be noticeable). That would cinch the diagnosis. You then get a new sensor, leave the paper spacer on the tip which is 'sacrificial' so as to provide proper spacing between the sensor and the drive plate.
The torque for the sensor retaining bolts is 9 foot-lbs.
That should solve this problem.
Roland