ignition control module

ignition control module
Akron, Ohio
Pontiac G6, 79 CJ7, Modified 84 C10
I've been having some problems with the CJ7, first the alternator now she stranded me and this time i think it's the ignition control module. I know it's been replaced on it once before. Do they go bad often? Reason being why i think it may be this is it runs fine til it gets real warm then she completely dies. Once it's cooled back off she starts right back up.
Your jeep probably still has the motorcraft ign. mod. These are junk. Had one in mine I swapped for an msd6a. Most people replace the boxes and keep the old one in the jeep so when the new one goes bad, they can keep swapping them while the other one cools to make it home. If you feel comfortable, when the jeep shuts down, check for spark. This will let you know if it is indeed a spark issue. You could also look in the carb as you open throttle about half way. The carb should spray a little fuel from the accel. pump as you do this. If no fuel sprays and you have spark, may be a fuel issue. If fuel sprays, and no spark, good chance it is the box. Also, describe the way it shuts down, slowly and starts bogging, or just all of a sudden shuts down.
Is it the stock ICM or an aftermarket?

when the MSD Off-road box in mine went out, it did the exact same thing. IT would run for 20 seconds then shut off. After a bit it would start up again and then die.
There is a reason yours is going out, so finding that reason should be a priority.
Check the wiring routes and the vehicle grounding closely. There is a good chance the Alt problem and the ICM troubles are related, like thru an insufficient ground.

EDIT: PC you beat me to it :) Darn these fat fingers :laugh:
PBM: If you decide to upgrade Summit sells a CDI box that works good, for less than the popular CDI boxes.
summit racing part# SUM-850602 is what I run in my Jeep now. Use it with the TeamRush dist. upgrades and you won't be disappointed.
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I agree with mylittlecj5. Just find out whether it is spark or fuel first. Then it is time to figure out why that isn't working. Also, as he stated, the team rush upgrade is really worth it. A properly executed ign. upgrade is worth it just for the fact you feel confident it will start when you want it to and keep running.
What about going to a D.U.I Distributor
Why would you want a drunk ignitions system? :laugh:

Your distributor is electronic already. Putting in an aftermarket box would be the best alternative. To go distributor less would be difficult.
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here is a lot of troubleshooting tips I was given when I went thru this same thing.
CJ, sorry for the outside link, but its way too much to condense and re-post.
MSD ignition box problems - JeepForum.com
Switching from one factory type ignition system,
('79 has a Jeep/Motorcraft ignition in it)
And spending $400+ dollars to switch to JUST ANOTHER factory style ignition system seems like a move sideways at best,
And to me, a move BACKWARDS, since the HEI clones all bring a lot of problems to the table with them...

Actually, there is a $25 alternative you can do that will give you the reliability of the HEI system, and keep you from having to hack up your factory '79 wiring harness...

It's the 'John Strenk "Stealth HEI"' conversion...

Here is a link to my version of that particular CONVERSION.... (conversion, not upgrade)
Junk Yard Genius.com 'Stealth HEI Page

The idea is to use the more durable HEI module in place of the Jeep/Ford/DuraSpark module you can't get a decent replacment for anymore...
(Everything is 'Import' and doesn't work very well... If at all!)

This is VERY easy, module runs about $20, and you will spend another $5 on connectors, diode, heat transfer paste, ect.

Plugs right back in where your module disconnected from, and you never know the factory module was replaced (except for it doesn't die all the time like the 'Import' modules do!)

There are other options, and I you would like to hear them, just ask...
JeepHammer, Is that you! Good to see ya buddy...
Yup, going back to the 'TeamRush' name for this forum.
TeamRush, Junk Yard Genius, JeepHammer all the same idiot in most cases!

this guy is awsome. everything i have done to my jeep came from him.
OK, enough butt kissing! :D
Start buying beer if you are serious!:chug:

Anyway, the easiest way to check to see if a DuraSpark module has given up, is when it checks out the next time,

Buy a cheap, $6 test light with an 'Ice Pick' probe on one end and an 'Alligator Clip' on the other end...

Jump out, connect a 'Test Light' to the POSITIVE side of the battery,
And pop off and probe the NEGATIVE side (Green Wire) of the Ignition Coil Connector while cranking the engine...

If the light FLASHES when cranking, the Distributor Trigger, Module, and wiring in between is working.

If the light DOES NOT flash, you have what is most likely a module failure...
Could be a coil failure, module failure, distributor mag trigger failure, or any one of a half dozen connection giving up when it gets warm...
Including the ground to the ignition module.

The $6 test light will tell you what is going on pretty quick, and will help you track down the problem in short order...
(Heat/Run Time related, I'm guess Module...)
Well TeamRush Iv'e been using your upgrade for several years and am about to use it again on my new (old) 76 CJ5 project if I can figure out the rat nest wiring from PO. Anyway there is a cold one waiting for ya when you make it down this way... :chug:
Well TeamRush Iv'e been using your upgrade for several years and am about to use it again on my new (old) 76 CJ5 project if I can figure out the rat nest wiring from PO. Anyway there is a cold one waiting for ya when you make it down this way... :chug:

I LOVE free beer!

Anyway, with a '76, you have some extra challenges...
'74-'77 used PRESTOLITE ignition system, and not the module or distributor is compatable.

You will have to change the distributor,
(I'd use the Jeep/Motorcraft distributor from '78 to '86, they run about $50 reman at the discount stores, and thy work GREAT!)

And once you switch the distributor over to a Stator type Magnetic Trigger with a good signal,
You can use about any ignition module you want to,
From (Jeep/Ford) DuraSpark module,
To GM HEI module,
To After market CDI module for 500% more spark energy than any of the single fire, stock type ignitions.

The Jeep/Motorcraft distributor will trigger all of these,
Work well for you,
Have no issues about bad gears or too much advance for your AMC engine, ect.

Let me know and I'll supply you with the diagrams for changing the Prestolite system out for something that actually WORKS when it's supposed to!
The diagram would be great and will be switching out the dist this weekend so again thanks. Oh and fridge is stocked with cold ones. :D Oh and cannot wait to be able to start the Jeep without all the snap.crackle ,and popping going on.....
Once you switch out the distributor for the Jeep/Motorcraft unit ('78 or '79 Jeep CJ with your style engine),
Reman distributor is about $50 so it's a steal for this upgrade...

Module can be wired as follows,


Remember to twist the trigger wires around each other, and keep them close to metal on the way to the module!

Keep the trigger wires AWAY from the coil power or high voltage wires like coil and spark plug wires.

Mount the module correctly,
This thread will tell you how to mount the module, but DO NOT use the wiring diagram in this link!
Junk Yard Genius.com 'Stealth HEI Page

Any old piece of aluminum will do,
or Radio Shack has 'Project Boxes' that are all aluminum or have aluminum lids that work GREAT as module enclosures.

Make sure you remove or drill reliefs for the 'Nibs' that stick down off the module,
Otherwise the module won't fit flat against the heat sink, and you will have overheating problems!

If you take a good look at the diagram above...
All you really need is this gadget,
MSD Ignition 8869 - MSD Wire Adapters
So you can plug directly into the Jeep/Motorcraft distributor...
Then you can run wiring to anywhere fairly easily...

The power supply wire to module and ignition coil is already in place,
'Green' wire between ignition coil and module is already there,
And there are already wires going to the distributor,
There is a ground wire already servicing the current module,

So all you really have to do is adapt what wiring that is already there to your application...
I'd even keep the connectors if I were you!

The coil will work with any of the ignitions, so it's fine to reuse...
I mounted my module on a full size computer CPU heat sink, I didn't realise they got that hot, glad I did. And I recommend artic silver paste for the compund between the module and it's heat sink, also use copper it cools better than aluminum.
The paste can be bought at radio shack, and an old CPU heat sink works great.
Check a local computer repair place they'll usually have a couple old ones just lying around you can get free. I also went a step further and polished the mounting surface of the module and the heat sink, I wanted the best heat transfer.
What can I say computers are my thing and old habits die hard.

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