Chrysler Repair: RE: 96 Dodge Neon - No Spark or Start, camshaft sensor, crankshaft sensor

Question
Hello Roland,

Sorry it took me a little while to get back to you, but this is in reply to the answers that you sent me below:

I did check the voltage at the crank sensor and it fluctuates between .06V and 6.34V it seems to change frequently when hand cranking.

The voltage at the camshaft sensor is .03V and 6.31V it does not fluctuate as frequent as the crankshaft sensor.

The voltage at the coil is getting between 10V and 12V while cranking.

Thanks again!

Kevin

I have a 1996 Dodge Neon, 2.0 litre, SOHC.  I just changed the head on the car.  After replacing the head and reassembling the components, the car started fine and ran perfect.  2 minutes into running the engine, the car shut off and I cannot get it to start back up.  I rechecked the timing and it is right on.  I replaced the cam and crank sensors and still no luck.  I checked the voltage to the cam and crank sensors and I am getting around 9.6 volts.  I also put another coil pack on the car and no luck there either.  There is voltage to the coil pack, when the key is turned on, it goes to 12-13 volts then the voltage goes away (energizing the ASD?).  I am really stumped on this one ... any ideas?


ANSWER: How about trying for fault codes:"on-off-on-off-on and leave on" doing that with the ignition key in 5 seconds or less elapsed time. Then watch the check engine which remains 'on', to see it begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat the count process to assure accuracy. Group the counts is pairs to form the two-digit fault code numbers, the last of which is always 55 (which means end of readout). Then write back or go to www.allpar.com/fix/codes.html for a code translation. We'll go from there if you have any codes.  
The coil pack 12v supply depends on the ASD being closed, and that closure depends upon the controller getting signals from the two sensors (e.g. working and the engine rotating). You could check the signals from the sensors by turning the engine over by hand with igntion switch 'on' and you should see the voltage oscillate between 0.3 and 5v between the other two wires on each of the sensors. It is normal to loose the 12v after a second or so of turning the ignition to the run position unless you start ceanking the engine over to produce signals/
Roland


---------- FOLLOW-UP ----------

QUESTION: I'm assuming that I should leave the sensors plugged in while performing the voltage test?

Also, I am not pulling any bad codes.  The only two codes I am retrieving are code "12" and "55"

Thanks Roland!

Answer:
Yes, leave the sensors plugged in measure the signals by carefully probing the connectors with pins to make contact. Turn the engine by hand via the crank pulley bolt, with the ignition in the run position. Also, check to see that the coil pack plug shows 12V when cranking on the dark green/orange wire.
Roland


ANSWER: Hi Kevin,
So we have output from the cam and crank sensors and 12v at pin 2 of the coil pack when craniking the engine over. That has to mean that for some reason the pcm is not pulsing the primary coils to ground once per crank revolution, of the signals are not getting to the coils. If your voltmeter quickly responds to pulsing then you could try looking at the voltage on pins 1 and 3 of the coil pack while cranking because it should show a decreased rms voltage if there is a pulsing signal rather than a flat 12V if there wasn't. If you do see pulsing and there is a solid 12V on pin 2 of the coil pack plug, then if you don't get spark either the coil pack is not firmly grounded on it mounting or it is no good. If you don't get pulsing on the primary wires then check continuity to see that they are connected (pin 1 of coil to pin 3 at pcm, pin 3 at coil to pin 2 at pcm) and if they are then it appears to me that the pcm is not functioning. Those are the only reasons I can identify for no spark. Please let me know what you learn.
Roland

---------- FOLLOW-UP ----------

QUESTION: Hi again Roland,

Here is what I found.  With the plug inserted in the coil, I checked the voltage at pin 1 while cranking.  It pulsated rapidly between 14.27V and 14.67V.  I checked the voltage at pin 3 and got the same results.  I also checked continuity between the wires and the PCM and they definitely are connected.

I grounded the coil pack a few days ago by running a wire from the negative terminal on the battery to the coil mounting bolts and that did not work either.

Thanks,

Kevin

Answer
Happy New Year, Kevin!
May I ask for your help?
I need your vote of confidence.
I'm in a close race to be recognized as 'Volunteer of the Month' at Allexperts
Purely symbolic, but it means alot to me.
Please click on "Thank/rate the expert" button below/left
It will take you to a page which asks "Would you like to nominate this expert...?"
Click on the "YES"
That's it.
Thanks for taking a moment to help a fellow Chrysler-owner.

Roland

PS:Do it now, the contest closes at 6pm central time.


Check the resistance of the primary winding (2 to 1 and 2 to 3 which should be about .6 ohms, and check resistance between the coil towers (8 to 15k ohms). If so, then I am at a loss as to why you don't have spark