# 1972 GTO no spark



## Chooko (Mar 29, 2012)

All,

If you happened to read my thread on my recent gauge issue, then you will know that I am currently working on getting my '72 GTO back on the road after years of storage. If you have not read the other thread, then...that's what I'm doing. 

I have been working on cleaning up some wiring in my engine compartment. The engine was swapped by the previous owner, and is a '70 GTO 400, and there is quite a bit of excess wiring in the engine compartment. I found a red wire that was attached to the positive terminal on my cylinder style ignition coil, but it was not connected to anything else, so I removed it. To the best of my knowledge, nothing else was done to the ignition coil area, but now I get no spark. 

As you can see in the picture, the red wire from the ignition goes to the ballast, and then a black wire goes from the ballast to the negative terminal on the coil. That is it. There is nothing on the positive side of the coil. Does this seem right?

I have verified voltage on the red wire with the key in start and run, and have verified that the ballast has continuity, and the coil has continuity across the positive and negative terminals. If I pull the coil wire off the distributor and hold it near a ground, I get no spark.

I have only removed wires that were loose on at least one end, so I can't think of anything I did that SHOULD have caused this, but that fact that I am getting no spark makes me thing I may have indeed been the cause.

Ideas?

Joe


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## BLK69JUDGE (Jun 10, 2010)

*and*

red hot into balast

the wire from the other end of balast goes to + on coil ...
I have never had balast resistor on a pontiac ...but...


then you need to reach under the distributor and grab the wire coming out of the bottom
and hook it up to the - on the coil


zooooooooooooom zooooooooom


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## Chooko (Mar 29, 2012)

That worked! Thank you very much!

Joe


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## Chooko (Mar 29, 2012)

While we are on the subject, does anyone know what the smaller cylinder with the green wire is? I just removed it because I dont like extraneous things hanging out. I dont think its ever been hooked up since I've owned he car, but I should probably ask before I get rid of it.

Joe


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## Chooko (Mar 29, 2012)

Can you guys tell that I SUCK at electrical?

Next issue. This morning the car refuses to crank. Here is what I have verified so far:

1. 13V across the battery terminals. 
2. From positive battery terminal to any other ground on the car, good voltage / continuity.
3. From starter body to any engine block, etc, continuity.

So I would say that the starter is receiving voltage, and is grounded, so she should crank, right? I get normal lights in the dash, etc. The car stays on a tender.

What am i missing?

Joe


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## BLK69JUDGE (Jun 10, 2010)

*well*

glad your getting somethings finger ed out

so your car is not in park

turn the collar in front of your key counter clockwise ,,,, like your putting a column
shift car in park...


also

thats a fast idle solenoid ,,,, It should pop out with the key on and click when key is turned off

if your not using it ,,,, save it ,,,, and the bracket together ....

if you wanna sell or trade I would be interested ...


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## Chooko (Mar 29, 2012)

All right, I got the car started. Had a bad splice in the wire coming from the ignition switch. now she fires right up.

Fast idle solenoid eh? I just did a couple of google searches on that, and I'm STILL not sure that I understand what it does. Can you give me a layman's explanation of its purpose?

Joe


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## BLK69JUDGE (Jun 10, 2010)

how do you remove a12 idle solenoid bracket | Moparts Restoration & A12 Forum | Moparts Forums


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## Fuddy (Aug 7, 2018)

Ignition circuit. 
My wife has a 72 GTO. It had resistor wire which I replaced with copper wire. I don't like resistor wires. So it has ballast resistor. There are two coil types, internal and external ballast. Be sure to use external ballast coil. Coil -- goes to distributor. Coil + to ballast resistor AND starter solenoid. Other side ballast resistor to ignition switch.
So with test light or meter you want power to resistor from switch on position (not off or accessory). You want power to coil + side when cranking. Reason is cranking voltage is low (maybe 9-10 volts), once started the ballast resistor drops voltage to coil + as power is going through it.
Point gap 0.016" or 30° dwell, new points/condenser. Be sure point plate braided wire to case is ok.
Block to frame ground strap clean, good tight connection.
She doesn't like vacuum advance so I take an old one, brazen the rod in place, cut it, mount it so now plate is locked in place.
She fine tunes via centrifugal springs and files the limit stop some until total advance where she wants (around 35°, all in by ~2400 depends on motor/setup).
Ford had a better idea so her Pontiacs I use a Ford starter solenoid mounted inner fender between battery and starter. So simple and easy. Battery + cable to it, other side to starter motor. Ignition switch crank position wire to solenoid switch terminal.

Sent from my SM-S320VL using Tapatalk


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## BearGFR (Aug 25, 2008)

Chooko said:


> While we are on the subject, does anyone know what the smaller cylinder with the green wire is?


I assume you're talking about the photo of your coil in the first post. That's a condenser. There should also be one inside your distributor and connected to your points (make there's one in there). A condenser (capacitor) is an electronic component that will tend to "pass" alternating current and "block" direct current. On cars like yours, they were used as filters to clean up power and also to help reduce or eliminate static in the radio by "passing" alternating current off to ground. The green wire will be the "input" and the outer metal body (which has a path to ground) will be the "output" for a/c current being "disposed of".

And, no offense intended, but disconnecting something just because you don't know what it does can get you into trouble 

Bear


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## Chooko (Mar 29, 2012)

Bear,

Thanks for the explanation. To be clear, I didn't disconnect it. I just removed it. It has not been connected since before I bought the car in about 2000. If I am understanding you correctly, the green wire would connect to the + side of the coil. Is that correct?

Edit to add: I am looking at a couple of generic diagrams online and they show it going to - on the coil?

Joe


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## Fuddy (Aug 7, 2018)

Yes, + side of coil. Inside distributor should be the condenser connected to points, which parallels the points, so essentially coil -- to ground.

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## BearGFR (Aug 25, 2008)

Chooko said:


> Bear,
> 
> Thanks for the explanation. To be clear, I didn't disconnect it. I just removed it. It has not been connected since before I bought the car in about 2000. If I am understanding you correctly, the green wire would connect to the + side of the coil. Is that correct?
> 
> ...


Condensers (capacitors) tend to pass AC current and resist DC current. Coils/inductors (what your ignition coil is, electronically) tend to do the opposite: they tend to resist AC current and pass DC current. I'd probably connect the condenser to the input side of the coil (not the wire that goes to the distributor but the 'other' side) to get the most benefit from it. More than likely this one is there for radio noise suppression, mostly on the AM band. After all this discussion - that's the only job it does and you could run without it if you want and not hurt anything :grin2:

The condenser/capacitor that's inside the distributor and connected to your points is a different story. It's "tuned" to the primary side of the coil and together those two components create an oscillating circuit that helps maximize spark and also makes your points last longer.

Bear


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