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Old 07-19-2013, 10:35 AM   #1
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No Spark 1995 YJ 4 Cylinder

I have a 1995 YJ 4 Cylinder that is not getting spark to the plugs. Have changed the coil, distirbuter, rotor, and crank sensor. What is the most likely culprit?

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Old 07-19-2013, 10:52 AM   #2
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Usually when there's a no spark situation the Ignition Control Module is bad.

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Old 07-19-2013, 11:14 AM   #3
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Usually when there's a no spark situation the Ignition Control Module is bad.
Not always, the ECM can also go bad and cause this. I would suggest to the OP to check the fuses for the ign. There is one under the hood by the battery and one under the dash by the PB assembly. If these are good then I would check to see if you are getting voltage to the coil. Not to long ago another fellow Jeeper had an issue like this and it was the coil connecter one plug was falling out of the connecter and not making contact to the coil.
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Old 07-19-2013, 11:25 AM   #4
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Not always, the ECM can also go bad and cause this. I would suggest to the OP to check the fuses for the ign. There is one under the hood by the battery and one under the dash by the PB assembly. If these are good then I would check to see if you are getting voltage to the coil. Not to long ago another fellow Jeeper had an issue like this and it was the coil connecter one plug was falling out of the connecter and not making contact to the coil.
Not sure how all of this works but should the coil have 12 volts to it any time the switch is on because it does not. I guess I need to read up on how the ignition works. I understand points and condensers but not much about electonic ingition. Guess that is what I get for being old.
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Old 07-19-2013, 11:51 AM   #5
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Check the fuses
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Old 07-19-2013, 12:03 PM   #6
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Check the fuses

Fuses are good but still no 12 volts at the coil
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Old 07-19-2013, 12:40 PM   #7
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Fuses are good but still no 12 volts at the coil
I'm still going with when this happens the prime suspect is the Ignition Control Module. I could be wrong but they seem to fail sooner than the ignition or computer module.
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Old 07-19-2013, 01:43 PM   #8
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Here's some diagrams see if they help you out and check everything before either module.
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Old 07-19-2013, 04:48 PM   #9
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Also according to my Chiltons book, you need to be checking for voltage while cranking the engine. Also try swapping out the auto shutdown relay under the hood by the battery with the horn relay.
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Old 07-22-2013, 10:32 AM   #10
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Thanks very much. Will have to try it this weekend. Only have limited time to work on the project. Do you know what triggers the Auto Shutdown Relay to shutdown the spark and fuel?
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Old 07-22-2013, 01:51 PM   #11
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Sure dont but from the looks of the diagram it only goes to the injectors, starter, and ign control.

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