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Duraspark wire identification

Travis Greever

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Feb 27, 2013
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14
I was wondering if anyone knows what wire is the "bypass" wire. Even better if you can tell me what wires are what.
I'm not sure who makes it as their are no markings on it, and I can't fiqure out how to post a pic of it. there are two wires buy themselves, one red and one white. then there are four wires one purple, one org, one blk and one green, these have a harness that goes to the factory harness, put the others are cut, I assume for the install of the new centech wire harness. ANY help would be appreciated.
 

Ovalis

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Jan 19, 2011
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386
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Are you trying to connect to existing wires that have been cut?
What year is your bronco? The wiring is a little different for 74, 75, & 76/77.
 

Jdgephar

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Sep 25, 2012
Messages
1,317
I don't understand that wiring diagram. Why cut the wire? Can't you just hook up the white wire to the "S" terminal on the relay instead?
 

Quick & Dirty

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Feb 15, 2004
Messages
826
That diagram is for an easy wiring conversion. It backfeeds the start bypass with power from the coil to run the electronics. It has to be cut so it doesn't run hot to the ignition retard all the time. IMO it's a hack method to wire one in. It uses the reduced voltage coil power to run the box, and cuts the full voltage coil power during start.

The red wire is power from the ignition switch. The white wire is ignition timing retard during cranking. Normally wired to the starter solenoid circuit.

One thing to be aware of if using much of the stock Duraspark harness;
The wire color changes across the connector. The white retard wire at the box connects to the red/blue stripe starter circuit wire. The red box wire connects to a white wire from the ignition switch. Can be confusing if you are looking at a factory wiring diagram and trying to match to colors on the box.
 
Last edited:

DirtDonk

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47,345
With the Centech harness you will need to use the supplied ballast resistor if you're using the stock, or equivalent stock type coil.

A Blue Grommet module gets 12v in run, but the coil still needs the reduced voltage through the wire to the positive side.

Paul
 

canary28

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Joined
Oct 19, 2007
Messages
51
I've been working on this and have it running, but not real well.
I'm going with a complete DSII system out of a ca. 1978 Granada. Does the coil need a fusible link/resistor (These function the same way as I understand it?) between it and the power source like the non-DSII system does? Is the fusible link that is already on the vehicle (1966 Load o Matic) supply the correct voltage to for the DSII coil?
Thanks!
 

Viperwolf1

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Yes, it needs the ignition resistor. No, the ignition resistor isn't the same as a fusible link.
 

Jdgephar

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Sep 25, 2012
Messages
1,317
That diagram is for an easy wiring conversion. It backfeeds the start bypass with power from the coil to run the electronics. It has to be cut so it doesn't run hot to the ignition retard all the time. IMO it's a hack method to wire one in. It uses the reduced voltage coil power to run the box, and cuts the full voltage coil power during start.

The red wire is power from the ignition switch. The white wire is ignition timing retard during cranking. Normally wired to the starter solenoid circuit.]

I don't like that diagram. Wire the module they way it is supposed to work. Red wire from duraspark to 12V keyed source, white wire to the start terminal on the starter solenoid, and the resistor wire to the coil +.
 

Quick & Dirty

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Messages
826
Does the coil need a fusible link/resistor (These function the same way as I understand it?) between it and the power source like the non-DSII system does? Is the fusible link that is already on the vehicle (1966 Load o Matic) supply the correct voltage to for the DSII coil?
Thanks!

I used the original points coil wire and spliced it to the Duraspark coil connector. The DSII uses the same resistor value as the points. The red wire at the box goes to ignition switch run terminal. The white box wire goes to the start terminal.
 

DirtDonk

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To be accurate, it's not really the "start" terminal. It's the "ignition" terminal on the starter relay.
I know what you're saying, but it's too easy to confuse the "S" with "start" here, and that would lead to some interesting times when the key is turned to RUN. ;D
As long as you use the "I" terminal, you'll be ok.

Paul
 

Jdgephar

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Sep 25, 2012
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1,317
To be accurate, it's not really the "start" terminal. It's the "ignition" terminal on the starter relay.
I know what you're saying, but it's too easy to confuse the "S" with "start" here, and that would lead to some interesting times when the key is turned to RUN. ;D
As long as you use the "I" terminal, you'll be ok.

Paul

Paul, just to be double clear, I do mean the "S" terminal on the starter relay, and not the "I" terminal to go to the white wire on the duraspark module (the timing retard wire). The "S" terminal only has 12V when the key is in the start position. The "I" terminal will have 12V when the relay closes, and then will have some partial voltage with the key in run (if the wire is not cut). I'd rather the duraspark timing retard wire gets 0V when the key is in run. I'm assuming many people run it with the "I" terminal and cut the wire, so I guess it works fine.

I would rather see people wire the Duraspark red wire to a 12V source, the ignition timing retard wire (white) to the "S" terminal on the starter relay, and then leave alone the resistor wire that attaches to the coil + and "I" terminal.

DurasparkFORDall.jpg


I'm curious if those that run the power to the duraspark module using the resistance wire (coil +) have more reliability issues that those who run it to a 12V source. The lower voltage would cause the module to run at a higher current, and maybe fail the module more often?
 

Viperwolf1

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There was no timing retard in duraspark systems before '79.
 

DirtDonk

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...The "S" terminal only has 12V when the key is in the start position. The "I" terminal will have 12V when the relay closes, and then will have some partial voltage with the key in run (if the wire is not cut)....

You're right. Not sure where my mind was last night. Thanks

Paul
 

Jdgephar

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Sep 25, 2012
Messages
1,317
There was no timing retard in duraspark systems before '79.

Viper, I'm referring only to the small retard in timing during starting. I know most people (including myself) use the blue grommet (Duraspark II), which has this feature. The red grommet ones (Duraspark I, used in Cali only) should also have this feature.

Early versions, Electronic Ignition, Ford Solid State ignition, and Breakerless ignition system as they called them before they called it Duraspark may not have it, I don't know.

Later systems have another connector to change the timing for altitude or other reasons, and those have different grommet colors.

Sorry for the confusion about the timing feature.
 

Viperwolf1

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Viper, I'm referring only to the small retard in timing during starting. I know most people (including myself) use the blue grommet (Duraspark II), which has this feature. The red grommet ones (Duraspark I, used in Cali only) should also have this feature.

Early versions, Electronic Ignition, Ford Solid State ignition, and Breakerless ignition system as they called them before they called it Duraspark may not have it, I don't know.

Later systems have another connector to change the timing for altitude or other reasons, and those have different grommet colors.

Sorry for the confusion about the timing feature.

I know what you meant, and no, they don't do that. The black ('74 breakerless), green ('75 solid state), blue (DS2) and red (DS1) modules do not retard spark during cranking.
 

canary28

Jr. Member
Joined
Oct 19, 2007
Messages
51
Glad to get this revived and get some experts on this topic, as I don't feel that it has been adequately covered anywhere on the web for those of us who apparently are wiring-challenged. I know this isn't that complicated, but I somehow managed to hot-wire mine the first try %). Thus my need for some clarification. Thanks for bearing with me.

Here's what I get out of this. Can yous check me to see if this is correct?

Red wire from Duraspark box goes to 12 v switched source (threaded post on back of ignition seems to fit the bill).

White wire from Duraspark box goes to 12 v source when engine is cranking, which is the 'S' post on the starter relay.

Splice the original (+) coil wire to the electronic coil harness. This uses the pink 'do not cut or splice' wire as the resistor so that the coil doesn't get more voltage than it needs.

Leave the brown wire on the 'I' side of the starter relay in place so that the coil gets 12 v on startup only.

Basically said in a few more words as Q&D says a few posts up:

"I used the original points coil wire and spliced it to the Duraspark coil connector. The DSII uses the same resistor value as the points. The red wire at the box goes to ignition switch run terminal. The white box wire goes to the start terminal."

This makes sense to me, as does the diagram posted by JD. My question regarding that diagram is, why is that diagram different than the one when I visit http://www.mustangsteve.com/conversion.html ? Is it because the 12 v high-performance coil can take the full 12 v and does not need a resistor?

Thanks!
Andy
 

Viperwolf1

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Aug 23, 2007
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Glad to get this revived and get some experts on this topic, as I don't feel that it has been adequately covered anywhere on the web for those of us who apparently are wiring-challenged. I know this isn't that complicated, but I somehow managed to hot-wire mine the first try %). Thus my need for some clarification. Thanks for bearing with me.

Here's what I get out of this. Can yous check me to see if this is correct?

Red wire from Duraspark box goes to 12 v switched source (threaded post on back of ignition seems to fit the bill).

White wire from Duraspark box goes to 12 v source when engine is cranking, which is the 'S' post on the starter relay.

Splice the original (+) coil wire to the electronic coil harness. This uses the pink 'do not cut or splice' wire as the resistor so that the coil doesn't get more voltage than it needs.

Leave the brown wire on the 'I' side of the starter relay in place so that the coil gets 12 v on startup only.

Basically said in a few more words as Q&D says a few posts up:

"I used the original points coil wire and spliced it to the Duraspark coil connector. The DSII uses the same resistor value as the points. The red wire at the box goes to ignition switch run terminal. The white box wire goes to the start terminal."

This makes sense to me, as does the diagram posted by JD. My question regarding that diagram is, why is that diagram different than the one when I visit http://www.mustangsteve.com/conversion.html ? Is it because the 12 v high-performance coil can take the full 12 v and does not need a resistor?

Thanks!
Andy

Don't rely on wire colors. Go by the pin locations. Pin 4 is hot in RUN, pin 5 is hot in START.

The ignition resistor is bypassed to get more spark energy out of the coil. I don't recommend that. It isn't necessary on a stock engine and there are better ways to do it if it is.
 

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DirtDonk

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I think we talked about this a few years ago Phil, but if not for start-retard, then what is the purpose of a wire that connects to the start circuit?

Why does it need to know when the engine is cranking, vs just getting a key-on signal from the ignition switch? Is there some need for more current handling capacity of two wires for a hotter spark? Since it's not on a resistor (for most Duraspark applications anyway), and it's not the source of the spark like the coil is, and can use extra voltage during the cranking, it seems a waste.
Some type of "dwell control" for enhanced coil energy production for an easier start?

Why all the trouble and expense to connect a second wire if not to do something really cool and mysterious? ;D

Paul
 
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