Finding switched 12 volt source

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yellow rose

yellow rose

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I have to convert a 73 Duster from the OE ignition to an aftermarket box. Last one of these I did was 1999 or 2000. For the life of me I can’t figure out where I picked up the switched 12 volts to run the new ignition box.

I also can’t remember if I just taped off the original coil wires or what I did with them.

TIA
YR
 
There is only one (two) switched ignition sources under the hood. Period. I said (two) because that refers to the cranking coil bypass circuit

IGN1, usually dark blue comes out of the bulkhead and branches off, depending on year, to feed the ballast, the VR, the alternator field, electric choke "if used" and some smog doo dads on some years. IT IS NOT FUSED OR PROTECTED in any way

IGN1 is hot ONLY in run IT GOES DEAD in cranking

The only source during cranking is IGN2 which is hot ONLY in cranking. It is NOT the same as the yellow "start" wire. Normally brown, it connects to the coil+ side of the ballast.

Basically you need to splice all of the ballast wires together and run the original coil+ wire off to your new ignition system power connection.

That car has a 4 pin ballast. If you are going to strip out the old harness parts, you can eliminate the wire that feeds to the "box" from the ballast and the 12V wire going to the box, as well, of course the two trigger wires and the old coil NEG wire

Be sure you don't end up dropping a wire out that leaves the VR or alternator field unpowered
 
67Dart273 said:
There is only one (two) switched ignition sources under the hood. Period. I said (two) because that refers to the cranking coil bypass circuit

IGN1, usually dark blue comes out of the bulkhead and branches off, depending on year, to feed the ballast, the VR, the alternator field, electric choke "if used" and some smog doo dads on some years. IT IS NOT FUSED OR PROTECTED in any way

IGN1 is hot ONLY in run IT GOES DEAD in cranking

The only source during cranking is IGN2 which is hot ONLY in cranking. It is NOT the same as the yellow "start" wire. Normally brown, it connects to the coil+ side of the ballast.

Basically you need to splice all of the ballast wires together and run the original coil+ wire off to your new ignition system power connection.

That car has a 4 pin ballast. If you are going to strip out the old harness parts, you can eliminate the wire that feeds to the "box" from the ballast and the 12V wire going to the box, as well, of course the two trigger wires and the old coil NEG wire

Be sure you don't end up dropping a wire out that leaves the VR or alternator field unpowered
Click to expand...


I don’t remember it being this complicated. I don’t want to strip out the harness. I just need to power the box.
 
Del;
if you put all the ballast wires together;
do you not create a live circuit back to the start solenoid?

When I did that, I ran into issues with the engine wanting to crank occasionally.
So I wired that brown circuit on a relay to isolate it.
That worked so well I also wired the other side thru a relay, and so my big fat,square-top Supercoil now gets battery voltage thru it's own ballast resistor. That coil really lives up to it's name.
 
No the yellow start wire is separate

You do not HAVE to strip out the harness wires. You can simply jumper all ballast resistor wires together, take the original coil+ and use that to power the new system. If you have MSD hook that wire to the MSD "small red"

What this will create, if you unplug the old Mopar box, is the original coil NEG wire is dead, the pickup wires are dead, and there will be power on the Mopar box connector, so "safe" that off

You don't even need to hack up the ballast connectors. You can get male-to male flag connectors and insert them into the original connectors. If you want to maintain a stock appearance, you might be able to "hack up" a 4 pin resistor and jumper all 4 terminals together. ---and actually, it's only two. One of the 4 goes to the old box
Original wiring:
Two of the ballast terminals at one end are already jumpered by the harness. Most harnesses you can look and see those at one end of the ballast

One remaining goes to the old box connector

Last one goes to coil+
 
IMG_20180303_162831.jpg

I'm pretty sure I use one of these wires under the dash but I can't remember which one it was now. I put my MSD in the glove box LOL .
 
YR. Was it a CD box like MSD? In that case it wouldn't have cared about the ballast resistor. You would have just connected the small gage red wire to the ignition and the box's main feed would have been connected to the battery positive.
 
Mattax said:
YR. Was it a CD box like MSD? In that case it wouldn't have cared about the ballast resistor. You would have just connected the small gage red wire to the ignition and the box's main feed would have been connected to the battery positive.
Click to expand...

Yeah, this is a Mallory box but the wiring is basically the same.

This is why I ran a magneto in my race car. Besides a battery fired ignition can’t match the Mag, they are much simpler and easier to wire.
 
The cigar lighter wire is a great 12 volt source for the non smoker.
just add a switch and a fuse
 
yellow rose said:
Yeah, this is a Mallory box but the wiring is basically the same.

This is why I ran a magneto in my race car. Besides a battery fired ignition can’t match the Mag, they are much simpler and easier to wire.
Click to expand...
IF the wiring is the same as a MSD 505/6/7 type box:
One wire is the on/off. On the MSD is was a small gage red wire. Autotronics suggested removing the factory positive wire from the coil and attaching connecting it to the MSD on/off wire. They even supplied a plastic insulated strip and a couple of tabs to make this a neat job - and reversible.
The real power for the CD ignition came from the car's battery. Mine and probably most mopar folks attached with a ring terminal at starter relay. Actually I've just changed that but that's not important. Any location wit ha really good connection with 12 or 10 ga wires to the power will work.

When the key is in run or start the MSD on/off wire gets power. it doesn't need a lot of current. As far as I can tell, it powers a internal relay that connects everything else internally to power from the big red wire.
 
Mattax said:
IF the wiring is the same as a MSD 505/6/7 type box:
One wire is the on/off. On the MSD is was a small gage red wire. Autotronics suggested removing the factory positive wire from the coil and attaching connecting it to the MSD on/off wire. They even supplied a plastic insulated strip and a couple of tabs to make this a neat job - and reversible.
The real power for the CD ignition came from the car's battery. Mine and probably most mopar folks attached with a ring terminal at starter relay. Actually I've just changed that but that's not important. Any location wit ha really good connection with 12 or 10 ga wires to the power will work.

When the key is in run or start the MSD on/off wire gets power. it doesn't need a lot of current. As far as I can tell, it powers a internal relay that connects everything else internally to power from the big red wire.
Click to expand...


I’ll take a picture of the instructions and post them here for this box. Frustrating that I put a similar box on my car back in 2000ish and I can’t remember how I did it. Getting old sucks.
 
I don't have any wiring info on Mallory stuff but here's the old Autotronics info.
upload_2020-7-27_20-56-42.png


This my understanding a factory 73 wiring. Two wires not shown on the connector go to the distributor.
upload_2020-7-27_21-1-31.png



Based on that, a little rework of the pencil marks in my MSD instructions so it shows how it would work with a '73.
upload_2020-7-27_21-12-58.png

The way it is shown in the MSD diagram above allowed easy reconnection to the factory box if the MSD failed.

You may not care about that with whatever you're doing with this Mallory.
So to boil it down, if its a CD ignition with the same type of hookups, these are the critical ones.
upload_2020-7-27_21-32-21.png


I haven't bothered with the jumper.
 
yellow rose said:
https://www.jegs.com/InstallationInstructions/600/650/650-667-6.pdf


Here is the instructions for the box. He is using the Unilite distributor. It was easier to post the instructions.
Click to expand...
Yup just like you said. Concept is the same.

Probably best not to draw power through the 5 ohm resistor. Del mentioned that earlier. It would prob work but why risk it.
Just connect that Mallory On wire to any convenient spot in the ignition circuit. The ring terminal is a minor pain to connect without a terminal strip but you could do it. I just did that for my tachometer wire.

Lemme look, don't think I took a pic.
Well I did! Converted the ring terminal to a tab like this. Then covered the bolt with shrink tubing.
No pic of that. LOL
upload_2020-7-27_21-49-23.png
 
I think Del also mentioned piggyback.
edit. I reread - he mentioned flag terminals - so yet another way.

Here's a picture of a piggyback.
Slip it on one of the ballast resistor tabs, except the far side of the 5 ohm.
upload_2019-8-5_9-28-24-png-png.png


upload_2020-7-27_22-2-57.png
 
Last edited:
I guess now I’m at the point I need to decide where to grab the 12 volts from, doing the least amount of damage to the OE wiring.

I’m thinking I may just pull the power off the fuse panel. Not sure if that is the best thing to do, or even a good thing...but that’s where I’m thinking I may get it at this point.

Any objections to this? If I’m thinking correctly, if I pull the power from the fuse block, I can leave the wiring at the ballast resister plugged in and just unplug the OE ignition box.

Of course, I could be nuttier than a jar of goobers too.
 
yellow rose said:
I guess now I’m at the point I need to decide where to grab the 12 volts from, doing the least amount of damage to the OE wiring.

I’m thinking I may just pull the power off the fuse panel. Not sure if that is the best thing to do, or even a good thing...but that’s where I’m thinking I may get it at this point.

Any objections to this? If I’m thinking correctly, if I pull the power from the fuse block, I can leave the wiring at the ballast resister plugged in and just unplug the OE ignition box.

Of course, I could be nuttier than a jar of goobers too.
Click to expand...

If your looking for switched 12v power to use as a “run” signal, the coil + wire would do the trick without any cutting of the factory wiring. The coil should be powered from the Mallory ignition box. So the factory wiring would need to be removed from the coil. That is how my MSD box is set up and how MSD instructions show to wire in the new ignition system.
 
yellow rose said:
I guess now I’m at the point I need to decide where to grab the 12 volts from, doing the least amount of damage to the OE wiring.

I’m thinking I may just pull the power off the fuse panel. Not sure if that is the best thing to do, or even a good thing...but that’s where I’m thinking I may get it at this point.

Any objections to this? If I’m thinking correctly, if I pull the power from the fuse block, I can leave the wiring at the ballast resister plugged in and just unplug the OE ignition box.

Of course, I could be nuttier than a jar of goobers too.
Click to expand...

You're not going to get 12V in Crank from the fuse box. Everything goes dead in Crank, except for IGN 2. Trust me, I've been down this road.

Test it... Put a meter on whatever dose block wire and watch the voltage as you crank. If you don't have 12v in crank, the box won't fire.
 
yellow rose said:
I guess now I’m at the point I need to decide where to grab the 12 volts from, doing the least amount of damage to the OE wiring.

I’m thinking I may just pull the power off the fuse panel. Not sure if that is the best thing to do, or even a good thing...but that’s where I’m thinking I may get it at this point.

Any objections to this? If I’m thinking correctly, if I pull the power from the fuse block, I can leave the wiring at the ballast resister plugged in and just unplug the OE ignition box.

Of course, I could be nuttier than a jar of goobers too.
Click to expand...
Now I'm lost.
I thought you were looking for a switched power source to turn on the box?
Are you now asking about the main power? No switch, no fuse. Direct heavy wire to a power source.
Mallory shows it to the battery, but note it can be any place in the line such as the starter relay (or for a Ford, the solenoid).
Also on the first page it says it does not matter if the ballast resistor is present on not. So its same as the MSD

This diagram is most representative of a Chrysler distributor.
When it says ballast not used here, its in reference to the coil. The Hyfire needs to be directly wired to the coil - no ballast in between.
upload_2020-7-28_8-31-59.png


upload_2020-7-28_8-48-11.png
 
There is no fuse protection on the ignition. This seems to be the norm.

Now what I have just done does put the heavy red power supply for the MSD on the protected side of the fusible link.
Two caveats:
1. I don't know if the way I have done this will result in the MSD seeing more electrical noise, and if so, how well the MSD's electronics will tolerate that.
2. My decision to do this had several reasons which were important to me and arguable particular to the car and its current state.
- It might be an advantage having the MSD draw power from closer to the alternator.
- I was adding a parallel alternator output wire anyway. The R6 wire connection at the bulkhead is not in top condition - hasn't been for a couple years.
- The ammeter will now read only battery charging and discharging. This is generally minor. At most the the MSD draws 1 amp per 1000 rpm.
upload_2020-7-28_9-5-27.png


I'm doing this now because the instrument panel is out.
 
Mattax said:
Now I'm lost.
I thought you were looking for a switched power source to turn on the box?
Are you now asking about the main power? No switch, no fuse. Direct heavy wire to a power source.
Mallory shows it to the battery, but note it can be any place in the line such as the starter relay (or for a Ford, the solenoid).
Also on the first page it says it does not matter if the ballast resistor is present on not. So its same as the MSD

This diagram is most representative of a Chrysler distributor.
When it says ballast not used here, its in reference to the coil. The Hyfire needs to be directly wired to the coil - no ballast in between.
View attachment 1715568895

View attachment 1715568896
Click to expand...


My bad...I’m talking about the switched 12 volts not the big wire to power the box.

If I’m remembering correctly, the big wire powers the box and the 12 volt switched wire is what turns the box off with the key.

I wired this same box to a 67 Firebird about 4 years ago and it was much easier. I just replaced the factory resistor wire with a regular wire and hooked it to the box.
 
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