Built In Ballast Resistor In Ignition Coil

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Sounds like the run side of your ignition is dead.
Could be the switch or the wiring either one, and Del can tell you all the connections and where to test.
He loves that stuff.

It might sound like I'm getting annoyed with him and abodyjoe, but i'm not at all.
I like to think we all have a pretty good relationship. (I just like to tease Del a little here and there all in fun)
They have a good point in making sure the switching and wiring is ok first.
You will need that ign run side to work, because it makes a convienient source for power for the HEI coil. :)
 
So you are saying this wire is dead when the key is in the on position?
 

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67Dart273 said:
This, in my opinion, is generally a bad idea if you are using conventional points or Mopar ECU.

The reason is the original design itself!!!!

These were all designed to OPERATE thus:

With the engine running, the battery/ system voltage is actually 14V, not 12. The coil, operating through the ballast, depending on RPM, sees something on the order of 10-12V when running.

BUT WHEN STARTING the battery voltage is NOT 14V, it's not even 12V, and in the cold of winter, hard starting, flooded, or if the battery is down some, actual cranking voltage at the battery might only be 10V

What this means is that if you STILL HAVE the ballast in the circuit, the actual voltage to the COIL under this condition will be VERY low.

So ALL manufacturers, Ford, GM, Chrysler, AMC ALL of them used the same design --- a coil / resistor combination, which IS BYPASSED during cranking to give you a hotter spark

Using a coil designed for 14V destroys this design concept.

Now, if you want to use a CDI type ignition, or HEI this is no longer true. In the case of my backyard HEI conversion, I'm only using a stock factory coil with the resistor bypassed, so in this case the HEI produces more spark and certainly "at least as much" as the original system.
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the ECU itself sees battery voltage, its only the coil that is regulated by the ballast to the tune of 6-7 volts when running and battery voltage when cranking, you can remove the ballast if you put a hotter coil on

you are correct, all makes used a form of resistance to lower voltage for coil but its not needed to protect ECU
 
I am using a push button start. Again when I push the bush button it starts up but when I let it go the car just dies. The run button that is connected to the Ballast is 12v + but when I Check the volt on the start side there is no power there. It is not dropped down to 6-7 volts there are no volts at all. So when I push the button 12 volts go to the coil and starts but when I let it go for some reason the run side is not pushing volts to the other side of the ballast. Maybe the ballast is bad? The car starts up fine when I by past the ballast but the coil is getting way to hot and when I used my volt meter on the coil it shows like 13+volts going into a 12volt coil.
 
I want to say that ballast resister is bad because the ignition side of it all works great when I by pass the ballast. no problems at all with it but when I use that ballast resister is when I start having all the problems
 
the ballast sounds bad then.. replace it and you should be good to go.. get the right one for the car.
 
The one on my car is a two prong but every time I look like on auto zone or advanced auto is shows a four prong. I am not sure what the rite one would be.
 
see what ohm the 4 prong it calls for is then buy a 2 prong with the same ohm rating. a real parts store should be able to look that stuff up.
 
TrailBeast said:
So you are saying this wire is dead when the key is in the on position?
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"run" is hot ONLY in run, not start

The bypass (top right) wire should only be hot in "start" not run. This is included in part of the test I posted. You must disconnect as I posted in order to isolate that brown wire for testing

So far as 2/ 4 pin ballast:

The EARLIER ECUs REQUIRED a 4 pin ballast

The later ECUs were redesigned and only needed a 2 pin ballast

The earlier points ballast, the later 2 pin electronic ballast, and the "coil side" of the 4 pin ballast are essentially all the same. You can use a 4 pin ballast, but it may not do anything.

Only way to ID an unknown ECU for certain is to ohm the 5th pin (if it's present) to all other pins and the case, to determine if it's hooked to anything.

Some 4 pin boxes have 5 physical pins, some only have 4

You already have a simplified diagram of a 4 pin box/ 2 pin resistor posted. Here is the simplified diagram of the older 5 pin box. Note that the other resistor goes to the wire on the box. Also notice the upside down "U" at the bottom of the resistor block. This cutout is how you ID which way to install the resistor so that the proper resistance is in the proper circuit. If you look at that diagram carefully, as well as the earlier diagram, you'll discover the ballast and coil circuit is unchanged, and IS IN FACT the same as for points!!!

In fact, if you were to carry a spare breaker points distributor for emergencies, you could just drop the points dist. in, disconnect the ecu and the coil NEG wire, and hook the breaker point dist. right up. No other changes!!!

Ignition_System_5pin.jpg
 
Sick_Six225 said:
I am using a push button start. Again when I push the bush button it starts up but when I let it go the car just dies. The run button that is connected to the Ballast is 12v + but when I Check the volt on the start side there is no power there. It is not dropped down to 6-7 volts there are no volts at all. So when I push the button 12 volts go to the coil and starts but when I let it go for some reason the run side is not pushing volts to the other side of the ballast. Maybe the ballast is bad? The car starts up fine when I by past the ballast but the coil is getting way to hot and when I used my volt meter on the coil it shows like 13+volts going into a 12volt coil.
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Something is severely AFU

The "start" source for a normal ignition switch is the brown bypass circuit.

If you leave the key in "run" you should get voltage, but lower, through the ballast via the run circuit. I thought that you had checked the ballast already. I agree with Joe, sounds like the ballast is bad

I still don't understand why you are using a push button?
 
66plyValiant said:
the ECU itself sees battery voltage, its only the coil that is regulated by the ballast to the tune of 6-7 volts when running and battery voltage when cranking, you can remove the ballast if you put a hotter coil on

you are correct, all makes used a form of resistance to lower voltage for coil but its not needed to protect ECU
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I have not read that a Mopar ECU can drive a hotter non-ballast coil. One could try that, but you may find melted epoxy running down your inner fender from the ECU. Even my after-market Crane XR700 ECU says to use a ballast with the coil, as I understand the original Pertronix Ignitor also requires.

The earliest Mopar ECU's also needed a 5 ohm ballast for the ECU supply. Those had the 4-pin ballast. The other ballast was ~0.5 ohm for the coil. I think the 2-pin ballast was the same ~0.5 ohm. You can't accurately measure 0.5 ohm with a multimeter, and the resistance goes up greatly with temperature, i.e. in use. Better to rely on getting the correct PN for your car.
 
BillGrissom said:
I have not read that a Mopar ECU can drive a hotter non-ballast coil. One could try that, but you may find melted epoxy running down your inner fender from the ECU. Even my after-market Crane XR700 ECU says to use a ballast with the coil, as I understand the original Pertronix Ignitor also requires.

The earliest Mopar ECU's also needed a 5 ohm ballast for the ECU supply. Those had the 4-pin ballast. The other ballast was ~0.5 ohm for the coil. I think the 2-pin ballast was the same ~0.5 ohm. You can't accurately measure 0.5 ohm with a multimeter, and the resistance goes up greatly with temperature, i.e. in use. Better to rely on getting the correct PN for your car.
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im running a bypassed ballast for the coil, not ECU. replaced the coil with a 3 ohm Petronix 60K E Coil.
 

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I have been reading a lot online about ballast resistors and it all talks about having point ignition. My distriputor is electornic, nothing special but a stock electronic ignition. does this mean anything about the ballast?
 
Sick_Six225 said:
I have been reading a lot online about ballast resistors and it all talks about having point ignition. My distriputor is electornic, nothing special but a stock electronic ignition. does this mean anything about the ballast?
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on mopar electronic Ign the box isn't driving the coil like an MSD, its just controlling ground side or the coil. all you need is a 3 ohm coil and thats it, full 12v to the coil and your good to go.
 
805moparkid said:
on mopar electronic Ign the box isn't driving the coil like an MSD, its just controlling ground side or the coil. all you need is a 3 ohm coil and thats it, full 12v to the coil and your good to go.
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So with MSD 6A box, blaster 2 coil and their billet distributor no ballast is needed?
 
plumkrazee70 said:
So with MSD 6A box, blaster 2 coil and their billet distributor no ballast is needed?
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MSD has a dedicated power and ground wire, then a 12v switch which turns the box on and off. i dont think it would run with the heavy power wire on the ballast or even the switch wire for that matter.

but the straight answer is no ballast with MSD
 
plumkrazee70 said:
So with MSD 6A box, blaster 2 coil and their billet distributor no ballast is needed?
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You have to understand that MSD is a CDI (capacitive discharge) design, which is completely different than what some of us call a "switching" design.

To get things down to the very simplest terms, breaker points, GM HEI, or Mopar ECU systems, as well as most single coil factory systems, Run power to the coil positive terminal, and the system SWITCHES the negative coil terminal to ground to generate the spark. There's more to that, but sort of.

CD (Capacitive Discharge) systems do not do this

MSD charges up a great big capacitor, similar to a camera photoflash. The trigger mechanism "fires" the ignition, which disharges the pulse of power from the capacitor through the coil.

The coil then, becomes a TRANSFORMER, with CD type ignitions, and has NO direct current (12-14V) through the coil at all.

There is WAAAAAAYYYYYYyyyyyyyy more to it than this but that is the very basics

THE REASON that a "switched" system NEEDS to "worry" about coil resistance and a ballast resistor is that

with older breaker points systems, there is a practical CURRENT limit before high current from a great big coil will destroy a set of points

The same, in some ways, is true of most "switched" systems such as the Mopar ECU. That box can only handle so much current. If you put a VERY low resistance coil on it with no ballast to limit current, you may very well burn up either the coil or the ECU
 
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