QuestionQUESTION: I have a 1995 Chrysler Concorde with a 3.5l V6 I have no spark on cyl 1 and 4. Coil pack 1 is not receiving a ground from the pcm. I checked the continuity of the wire between coil 1 and the PCM connector and found 2 ohms. The PCM has no codes in it. so I replaced the PCM and I still have the exact same problem. Not sure where to go from here I tried to check the powers and grounds to the PCM but I have a Haynes manual and it does not show the powers and grounds in it. What else could be causing this issue? Also if you could I need the pin numbers for the powers and grounds on the PCM. Thank you very much.
ANSWER: Hi Jared,
What about the coil pack proper? Did you measure the primary resistance between the 1/4 pin and the common 12V primary pin at the plug which should be 0.45 to 0.65 ohms. And also check the resistance between the 1/4 spark towers which should be 7-15.8k ohms. You would also do well to compare the measurements with those for the other 2 coils. I would believe that if there were an issue with the pcm power/ground leads it would affect all three of the spark coils. But I can give you those in my next response, if necessary.
Roland
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QUESTION: The resistance on the coil is fine the PCM is not grounding coil 1 coils 2 and 3 are both being grounded just fine. I checked the wire between the PCM and The coil and it checks out fine. The PCM is not grounding the coil for it to fire. I would agree that the powers and grounds are probably not the problem but I still would like the pin numbers just to verify because something is causing the PCM to go haywire. Thank you for your quick response.
AnswerHi Jared,
Another other possibility is that your cam sensor/cam sprocket interface spacin is marginal such that it not producing the pulses for those particular rotational points of the engine. It may be that it is not close enough, or there may be an out of roundness or free play in the cam shaft bearing. You could take a look between the tan/yellow wire and the black/light blue wire of the cam sensor (or between pins 44 and 4 at the pcm) to see if the voltage changes from 5.0 to 0.3V reliably at each of the segments of the cam sprocket. Of course you do this by turning the crank pulley bolt by hand with the key in the run position, which may not replicate the effect at actual operating rpm's. You would need a scope for that situation.
The relevant pins of the pcm are:
3 12v battery supply
5,11,12 grounds
9 12v ignition run/start supply
Another possibility you may not have considered is that the middle coil of the pack, which services 1 and 4 plugs maybe actually labelled as coil #2, and its white wire goes to pin 17 of the pcm. Did you check that one or did you check the red wire to pin 18 or the black one to pin 19 of the pcm? Also, checking continuity is one step, but also check to be sure each wire isn't shorted to ground as well.
Roland
PS Please 'rate' my answer. Thanks
