Chrysler Repair: 1996 3.8L V-6 wont start/no codes/one spark only, powertrain control module pcm, powertrain control module

Question
I change the Camshaft Postion sensor as you sugguested but I still only get one brief spark with the spark plug grounded during a cranking cycle.What should I do next? ODBII code check shows "no faults detected" ODBII "View Data" during cranking does not indicate anything out of the ordinary.

Original Question was:
My vehicle is a 1996 Chrysler Town and Country LXI 3.8L with 85,000 miles. My problem started three weeks ago. I was driving down the road my engine shutdown without a sputter or a cough. I put the transmission in neutral and it cranked right back up again without any trouble. Two weeks later, after driving it everyday, the same thing happens again. Then, three days after that it stalled again and has not started since but it does cranks over. I have put a tester on the fuel ejectors and they indicate they are firing during the duration of the cranking cycle. Spark plugs have fuel on them after cranking. I have pulled the new spark plugs and grounded them and only get one brief spark at the beginning of the crank cycle. Fuel pressure at the fuel rail is 49psi. I have change the crankshaft sensor and put in a new coil distributor pack without any change in spark plugs. I have check fuses and swap identical relays for Auto Shutdown Relay, but still would not start. I checked codes by turning the ignition switch: "on-off-on-off-on and leave on" doing this in 5 seconds or less I get 12 and 55. 12 is for the battery being disconnected and 55 indicates end of check.The van has a camshaft sensor but believe that is more related to fuel distribution and not spark plug firing, but I am not sure. If it also could affect the firing of my spark plugs please let me know. I have also fully charged my battery. My problem seems to be in the fact that my spark plugs only fires once briefly and I do not know why. I hope it is not the Powertrain Control Module (PCM) and if it is, why does it give me codes 12 and 55. I could would appreciate anyone assistance so I do not keep throwing money at parts I do not need.  

Answer
Hi David,
The 'one spark' is suggesting that the ASD is opening up because it is not getting the go ahead from the controller. The controller assesses whether the engine is turning over from the crank (and the cam?) sensors sending it pulses. So I would begin by checking that the ASD is falsely opening after a moment of cranking by testing for 12V at the dark green/orange wire of the alternator during cranking, which is in fact the same output of the ASD that also powers the spark coil. If you see the ASD is dropping out, then I would check for pulsing of the cam and crank sensors: put fine straigth pins through the insulation of the ground wires (black/light blue) and the signal wire of the crank (gray/violet) and the cam sensor (tan/yellow). Then turn the ignition to "run" and use a voltmeter to measure between each signal wire and its ground wire while you turn the engine by hand using a socket wrench on the crankshaft bolt. You should see the voltage pulse between 5V and 0.3V three times for each full revolution of the crankshaft. If you get that, then check for continuity of the signal wires to the controller plug (crank to 24, cam to 44). If you don't get the pulsing on one or both of the sensors verify that there is 9 volts on the sensor supply wire (orange) of both sensors. If you have the 9V then and no pulsing then that sensor is bad or not mounted close enough to the surface that it is supposed to be sensing. If you have pulsing and continuity to the controller plug and still the ASD won't hold, then either the ASD is no good or the engine controller is no good. To check the ASD you could try substituting another relay with the same number (and not related to the engine operation) to see if that causes the ASD to hold. So if everything with the sensors seems OK but the ASD or a substitute ASD won't hold, it pretty much has to be the engine controller. But you need to test the sensors before concluding the controller is no good.
Please let me know what you learn. The powertrain controller may not set a code if the threshold fault value for the code to be set is not crossed, I suspect, so I wouldn't count on it to give you the code for the
'one spark'. I agree with you about not throwing parts at it, so do the tests and let me know.
Roland