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Discussion Starter · #1 ·
Some background. 1983 CJ7 with a swapped in 304 with TR upgrade ignition system (no MSD module). Jeep wired with Centech wire harness which uses a ballast resistor instead of a resistance wire........The problem(s). About 2 weeks ago right at the tail end of some wheeling I noticed what seemed to resemble a relatively serious miss but only under load. On the way home the "miss" got a lot worse and within seconds she died dead. After a tow home it was determined that the problem was a bad ignition module (the square box on the drivers side fender). Popped in a new one and it ran like a champ. Till today........A little more background that may be relavent. Yesterday I was trying to hook up a plug for trailer lights and was having a bitch of a time. Not thinking much about it I spent a fair amount of time with the ignition switch in the run position since the turn signals will not operate in the accessory mode. Never did get the lights figgered out but the jeep fired right up and away I went. Today I motored about town on various missons here and there with no problems. After work I got back to the light issue and once again spent a fair amount of time with the key in the run position. Got the lights taken care of and buttoned everything up and tried to start to go home. No Joy. Crank and crank but no start. Once in awhile it would just barely sputter like it was going to but never did. Just the barest of sputters. Got under the hood and found the ignition module was SMOKIN hot. Too hot to touch. Hmmm I sez and head to the closest Napa for a replacement. R&R'd that puppy and she fired right up. Left it running while I went to wash up. Came back about 5-10 minutes later and find it stalled. Crank, crank, crank but no start. Pop the hood and smokin hot ignition module again. Hmmm I sez and head to Napa for another, and a ballast resistor just for s&&ts and giggles. R&R both of them and crank, crank, crank no start. I am not a world class ignition expert so I am at a loss. I know the resistors job is to drop voltage but I can't for the life of me remember what it is supposed to drop voltage to. I "thought" it was to the ignition module but I may be all wet. ANY help would be greatly appreciated but especially from an Ignition God that can say without a doubt that "This is your Problem. Do This and All Will Be Well".

 

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1. The ballast restistor drops the positive (12 volts) to the coil. The final voltage is about 8.7 volts.

2. The Resistor connectos to the positive side of the coil. The negative side of the coil then connects as a signal return to the ignition module.

3. Ballast resistors usally open when hot. They also often increase in resistance. However when the resistor cools... it can "heal" itself enough to pass voltage.

4. Check the Grounds of the module... the case should be the ground.

5. Check the coil.

6. I think you're chasing your tail ... and are on the wrong track. You have to find out what's killing the ignition module... not just keep replacing it.

Those are where I'd start.

 

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Discussion Starter · #3 ·
I'm not really chasing my tail and at the moment I'm not on "any" track. That's the problem. The first time I assumed it just plain ol' bit the dust. I've had it happen before on other ford products. The second time I assumed it had fried because I had had the ignition on so long. When it fried just sitting there idling is when I decided there was a "real" problem. The coil is fine. I have a brand new spare I popped in as a quick check. It made no difference. The resistor is new, the coil is new, the module is new (again). The only thing on your list I haven't checked is the module ground. I'll give that a look in the a.m. Past this though is where I'm at a loss.

 

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time ot break out the VOM, the testing diagrams in a service manual and figure it out.

id also sand a few of hte nolt holes the ign box mounts with to make sure of a good ground.

IM sure TeamRush could help you diagnose a problem such as this if only he were around.

we need a huge "TR" to signal in the sky like calling for Batman!



OzarkJeep

"Bare foot girls, dancing in the moon light..."
 
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