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Unread 08-22-2015, 09:09 PM   #1
Chrisinchwk
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82 CJ7 coil problems

I have an 82 CJ7 258 all pretty much stock. Tonight out of the blue it would only turn over run for less than a second and die. After several attempts to start it i noticed the wire going to the coil was really really hot. If i turn the key to the run position it gets hot again. If I turn the key on ut unplug the red wire to the starter solenoid it doesn't get hot. I am thinking its my coil. My ohm meter seems to have died on me. Any thoughts? Coil is not stock, thinking its definately not an upgrade either.
I checked the voltage at the coil with the starter solenoid un plugged, i get 4 volts. FSM says i should be getting 6. Battery is full charged. Any thoughts why the positive wire going to the coil and starter solenoid heats up as soon as i plug it into the solenoid??
Thanks.

20150822_200305.jpg  
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Unread 08-23-2015, 12:46 PM   #2
Chrisinchwk
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Anybody
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Unread 08-23-2015, 12:52 PM   #3
LumpyGrits
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Cj

12VDC in start mode.
6VDC in run. There is a resistance wire in the loom that runs along the firewall.
Is there a separate resistor on that coil?

LG
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Unread 08-23-2015, 01:45 PM   #4
Chrisinchwk
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Quote:
Originally Posted by LumpyGrits View Post
12VDC in start mode.
6VDC in run. There is a resistance wire in the loom that runs along the firewall.
Is there a separate resistor on that coil?

LG
No seperate resistor on the coil. Im not sure which wire is the resistance wire. The one that is getting hot is orange. Havent tried voltage during starting. Dont like to leave the wire plugged in long. It has already melted it a little.
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Unread 08-23-2015, 02:08 PM   #5
Mike Romain
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The fat soft orange wire is the resistor wire. A common failure point is the crimp connector on that where it hooks to the wire going to the solenoid, about a foot away from the coil inside the loom. It should have high heat duct tape on it from the factory, it gets too hot for electrical tape. It also has to be a crimp connection, solder affects the wire's properties.
Leaving the key on with the engine off makes those wires get hot, the coil will even cook (had one go cherry red on me once) and the ignition module will melt out pretty fast.
If you have no spark and things are hot, I would be looking close at the ignition module to make sure the goo hasn't melted out of it.
Have you tested the resistance on the coil circuits?
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 08-23-2015, 02:42 PM   #6
Chrisinchwk
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Quote:
Originally Posted by Mike Romain View Post
The fat soft orange wire is the resistor wire. A common failure point is the crimp connector on that where it hooks to the wire going to the solenoid, about a foot away from the coil inside the loom. It should have high heat duct tape on it from the factory, it gets too hot for electrical tape. It also has to be a crimp connection, solder affects the wire's properties.
Leaving the key on with the engine off makes those wires get hot, the coil will even cook (had one go cherry red on me once) and the ignition module will melt out pretty fast.
If you have no spark and things are hot, I would be looking close at the ignition module to make sure the goo hasn't melted out of it.
Have you tested the resistance on the coil circuits?
When you say leaving the key on will cook it, i am talking 5-10 seconds its too hot to touch. I am in the process of buying a new ohmeter. I found the crimps and will double check them. How do i test the ignition module? Are you talking about the onw on the driver side fender?
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Unread 08-23-2015, 03:35 PM   #7
Chrisinchwk
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Resistance for the coil is 50 ohms between + - and 800 ohms between distributor lead and +. Both well outside OEM. but would this explain the hot wire. I have a new coil but am hesitant to put it in until i figure out the hot wire problem.

FSM says if engine runs only in start position (my wife held it there by accident, dont ask) but it kept running until she let go. Anyway FSM says open in resistance wire or excessive resistance. Other than checking the resistance ( 3.4 0hms FSM says 1.35) how do i fix that
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Unread 08-23-2015, 06:26 PM   #8
Chrisinchwk
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Surely somebody on here knows whats wrong
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Unread 08-23-2015, 11:43 PM   #9
Chrisinchwk
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So with the key on i get battery voltage at bkth the coild and starter solenoid and the resistance wire gets very hot. With the wires unhooked it doesn't matter which wire i hook back up either make the resistance wire hot. Jeep runs for 2 seconds and shuts off. If you hold it in the start position it will keep running. Question now is how do i fix / replace / eliminate the resistance wire??? Can anyone explain why it is getting hot??
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Unread 08-24-2015, 04:37 AM   #10
Mike Romain
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It gets hot because it is a resistor that turns some of the power into heat. A bad connection also has resistance making even more heat.
Your ignition module also has two power circuits, one for start and one for run.
You can run a temporary jumper from the battery positive to the coil positive and see if it starts. That will verify the wiring there. You will have to remove the jumper to shut it off.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 08-24-2015, 07:53 AM   #11
Chrisinchwk
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Quote:
Originally Posted by Mike Romain View Post
It gets hot because it is a resistor that turns some of the power into heat. A bad connection also has resistance making even more heat.
Your ignition module also has two power circuits, one for start and one for run.
You can run a temporary jumper from the battery positive to the coil positive and see if it starts. That will verify the wiring there. You will have to remove the jumper to shut it off.
Thanks Mike, Ill try the jumper shortly. Im tracking the electrical resistance causes heat but should the wire get hot enough to not be able to touch it? I checked the crimps on both ends and the look fine. Any other ideas if I need to replace it to make it run? Sad that a little piece of wire is preventing me from driving my jeep.
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Unread 08-24-2015, 08:32 AM   #12
Mike Romain
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Something is causing the wire to get hot, like a coil with an internal short. It has to be drawing big power to get too hot to touch fast, but even a good coil can turn cherry red from leaving the key in run with the engine off.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 08-24-2015, 08:51 AM   #13
Chrisinchwk
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Quote:
Originally Posted by Mike Romain View Post
Something is causing the wire to get hot, like a coil with an internal short. It has to be drawing big power to get too hot to touch fast, but even a good coil can turn cherry red from leaving the key in run with the engine off.
I otally agree, it acts like something is shorting out. If I unplug the starter solenoid and both wires from the coil no issues with turning on the key. If I just plug in the starter solenoid the wire gets hot. If I just plug both wires into the coil the wire gets hot again. This is making me think it is not the coil shorting out as the wire gets hot without it plugged in. When this first started I was checking for slop in my tie rod ends so I have my wife turning the steering wheel. Do you think it could be something in the steering column shorting?? Or any other ideas; I don't even know where to begin.
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Unread 08-24-2015, 02:20 PM   #14
Chrisinchwk
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The saga continues. I unplugged the ICM, now if I plug in the coil the resistor wire doesn't get hot. Makes sence since the coil groinds back through the ICM as far as I can tell. But if I hook up the starter solenoid red wire the resistor wire gets hot again.

Anybody have any idea where to go from here?
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Unread 08-24-2015, 07:43 PM   #15
Chrisinchwk
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Jumpe a wire from the battery positive to the coil with the positive wire off the starter solenoid. Started and ran great. Does this tell me the starter solenoid is done. Had ICM tested goid. Replaced the resistor wire with a 1.35 ohm resistor.

Help??
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