Ignition module or coil???

JeredYJ

New member
My 91 YJ 4.0 is not starting. It will turn over, but no start. The fuel pressure is fine. I pulled the wire from the coil to the dist. cap and there is no spark. How do I know if I should replace the ignition module or coil?? Thanks.
Jered
 

Another thing: It seems to have the most difficulty starting when it's very wet and rainy for a few days??? thanks. jered
 
The coil will be the easiest to change out and check. Check the 2 small leads that are attached to the coil, there should be a voltage on one of them from the ignition mod. If there is no voltage, then the mod is hosed. If there is a voltage, then the coil is hosed.
 
If you have a voltage meter with the resistance(ohms) setting you could check the primary and secondary resistance of the coil to see if coil is bad. First disconnect the coil. Then, using the ohms meter, put one contact on the neg. terminal and one on the pos. terminal. The resistance depends on the coil type i believe. The primary resistance for a Diamond coil should read 0.97 to 1.18 ohms. For the Toyo denso coil, it should be 0.95 to 1.20 ohms. To check secondary resistance put one contact on both the pos. and neg. terminals and put the other on the high tension terminal that your coil wire to the distributor hooks to. The resistance for the Diamond should be 11.3 to 15.3 k-ohms (the meter should have a setting for this, i believe it means thousands). The Toyo denso should have a resistance of 11.3 to 13.3 k-ohms. It says if either of these vary too far the coil is most likely bad.

od
 

Take the igniton module off and go to autozone. They can test it for free. If you have no spark thow, that is not your problem. It does not create the spark.
 
Take the igniton module off and go to autozone. They can test it for free. If you have no spark thow, that is not your problem. It does not create the spark.

my jeep would just shut off while driving, it WOULD NOT have any spark, and it was the module.
 
Non the less the module does not create the spark. Mine was bad and my jeep still ran. Just a little ruff.
 
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