Hate to do this..12v ign wire "hot" to touch!? HELP?! - JeepForum.com
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Unread 05-02-2013, 12:58 PM   #1
JUNK726
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1983 CJ7 
 
Join Date: Oct 2008
Location: ROSEVILLE, CA
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Hate to do this..12v ign wire "hot" to touch!? HELP?!

yup..i am sorry guys..i KNOW this has been BEYOND beat to death!! i have spent 2 days on this tfi upgrade in my 74 J10 BEFORE i resorted to asking help on here!...so here's the rundown..i upgraded to the '78+ distributor..ALL the required parts of tfi..blah blah..here's my issue...(and i have read EVERY site/post possible on this!! til i am sore and blue in face and dizzy) my switched 12v wire to coil gets HOT (to touch) when i hook battery up, and turn key...(only to run)..NOT turned over to start!...AND i ONLY READ 4v at coil!!??!!...ANY ideas or input as to why or what i am doing WRONG?? like i said...this lame post was last resort..i just feel like i wasted my entire weekend! J10 will not turn over....i just dont wanna burn up my new truck or its expensive tfi parts i JUST bought and installed....thanks guys! i KNOW it is something simple i am missing! I am no genius..BUT i did conquer a 4.0 swap into my cj7 and THAT was easier than this truck! ugh..explain that to me.. PO painted everything black under hood..so i am hoping solenoid/starter is hooked up correctly....i put new starter cable on to solenoid...old one was rotted...pulled starter to drop oil pan..maybe i messed it up...

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Unread 05-02-2013, 01:15 PM   #2
pleontks
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1976 J-Series Truck 
 
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so, you switched from points to and electronic distributor with larger ford cap and duralast box. Right?

Your 12v should be ran through a resistance wire or ballast resistor before reaching the coil. Should be @6v at coil. Your points system had a ballast resistor (the porcelain thing on the coil) and the electric system uses a resistance wire. If your ballast resistor was good, put it back on, they do the same thing.
If you have the prestolite (75-77), it runs off of 12v.
And my msd runs off of 12v.
Points and duralast are 6v.

Also, make sure your distributor ground (black wire from dist) is grounded. Mine is ran to my dedicated engine ground bolt.
And check for loose connections or messed up wires.

I remember when I did mine. So much reading.
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Unread 05-02-2013, 01:35 PM   #3
JUNK726
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yup! i switched out the points for the larger ford stuff...just went and got a ballast resistor to mount to firewall..then route 12v to it and then to coil..(?) im assuming..my biggest fear was burning up the ignition module (blue grommet one)...glad to hear the new coil is supposed to read 6v..i have read a TON and everyone says 12v to coil..(which still may get different ideas/advice)...but ima try it with the resistor...already ran a solid ground into the black wire (harness side) of distributor and module..so i should be good there! thanks guys!! well..back under the ol hood we go! im SURE i will laugh at myself WHEN i conquer this...
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Unread 05-02-2013, 02:10 PM   #4
JUNK726
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anybody also know if when you fab a coil bracket (im using stock bracket with 2 "L" brackets attached to it and coil)..do you also need to run a ground wire TO the coil bracket? dumb question..but i have the edelbrock aluminum intake..and i MAY be overthinking this! just trying to cover my bases! thanks guys!
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Unread 05-02-2013, 03:39 PM   #5
JUNK726
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ok..here's the update..AND next dumb question!...got the ballast resistor hooked up...(THEN i ripped into the PO handy wiring harness..im frustrated to point of tracing old wires..EVERY one of em back to firewall)..all i can say is my 12v ign hot wire gets 12-13v by itself when i turn key..AND it is cool to touch! BUT as soon as i hook wire up to ANYTHING (ballast, or wire to coil)..it becomes HOT to touch!?.....im stopping before i burn up my investment, and need a brain break....ANY ideas what i am doing wrong? or where i should look? seems strange to me..or beyond simple and i am not grasping it...sorry guys!
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Unread 05-02-2013, 05:16 PM   #6
pleontks
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don't need ground to coil bracket. Coil's made out of plastic

That makes no sense about the wire getting hot. Make sure your battery's not overcharged? And wire isn't cracked and grounding out somewhere?
Do you have anything else hooked to coil or resistor when hooking up 12v wire?
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Unread 05-02-2013, 08:02 PM   #7
JUNK726
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ok...so coil is internally ground...sounds good...and NO..i isolated the 12v wire directly from the firewall out of the harness (wanted to make sure the wire wasn't "nicked or spliced")...soon as i turn key read 10.94 volts every time..with fully charged battery....SOON as i hook wire to coil wire it gets hot hot to touch!..then i tried hooking it to ballast resistor...resistor got hot as i expected..BUT then i got NO voltage across it to wire on other side...
i just am more concerned about starting a fire under hood now than getting jeep running now! yikes..
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Unread 05-02-2013, 09:41 PM   #8
JUNK726
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well..found ONE of the problems..the "main" 12v wire had some major resistance (plus wire felt "rubbery" compared to others..prolly cuz it was frying!) so i replaced it...pulled harness from firewall plug and discovered TWO 12v wires coming from SAME metal tab in plug! it was capped off (may explain a little) BUT i STILL am not getting motor to crank over! the solenoid won't even click! im confused now (make that brain fried)..my weekend was a couple days of mind numbing forum reads and wires... oh well...hoping i can figure out why it wont even attempt to crank...i will check solenoid in morning..was too intimidated/scared of garage fire to attempt any solenoid jumping or anything...thanks guys for the help! hit me if ya can think of anything to check or what i am doing wrong!
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Unread 05-04-2013, 02:04 AM   #9
JUNK726
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well..if i knew how to delete my post/dumb question above..(all of em!) i would...sorry guys!! let's just say...when you cut the pigtail plug of wires off the back of the alternator..make SURE you hook up the CORRECT lite blue wire to cranking 12v side of solenoid!!! (there were 2..and of course..i didn't check cranking volts on it..i just assumed i hooked right one up!) well...im the dummy! BUT good part was i was able to repair/replace some shoddy wires in harness from PO as i searched...sooooo...in the end..she fired right up!! thanks guys for the patience and help along the way! Now in morning i start routing vacuum lines correctly and ridding the emissions/etc's i dont need! as MANY as i can since she's a '74 AND going to end up in midwest! Thanks all! Been awesome being on here...GREAT advice and all ur guys knowledge is beyond appreciated!
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