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Voltage to coil, new coil, no spark! help

jazclrint

NAXJA Forum User
Location
Plymouth, Maine
My Jeep has a bit of a rep in my family for always starting right up. But it started hesitating from time to time for a while now. Now, it just won't start. My gf's mom moved it around the driveway twice one night and now it won't start. Some troubleshooting shows that the crank sensor is working, and that voltage is getting to the coil, and the coil is good (brand new) but no spark is coming out the other side of the coil. Theory is that the signal going to the coil is not right somehow. Any ideas?

Thanks,
Rich
 
"What voltage? The 12v power or the 5 volts trigger?"

Well, we were getting the 12v when you first turn the key on, then when we cranked the engine over we were getting some sort of voltage pulse. I'm not completely sure because I was the one cranking. but knowing I need to be looking for a 5v trigger is helpful.

Rich
 
Important - is the voltage to the coil constant? If you have an analogue meter, connect it and watch it while someone else cranks the engine.

A coil doesn't fire because it has voltage supplied, a coil fires because that supply is interrupted. If there is a constant voltage applied, the magnetic field doesn't collapse in the primaries and induce the current in the secondary windings - which could be your trouble.

Sounds like something is causing your trigger signal to not "trigger" - sounds like you'll have to backtrace to figure out what that might be...
 
jazclrint said:
Where do I find a good electrical schematic?

I haven't had a chance to scan all of mine yet, but if you check the reference section of your local library, they probably have Mitchell or Motor repair manuals - the ones that shops use. You should be able to Xerox the parts you need from those...
 
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