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Clarification on ignition switch contact development?


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Okay- this may be hard to follow...

I am working on my wiring harness, modifying it for an MSD Digital 6+, and use of a mini starter with integral solenoid.  The apron mounted solenoid has been removed.

I need +12v for the MSD box when the ignition switch is in the on and start positions.

Looking at the Ford wiring diagram it looks like the Ignition red with light green trace wire is energized from the ignition switch while in the on position through a ballast resistor, and directly energized from a stand alone contact on the apron mounted starter solenoid when in the start position.
 

So here are the questions

1) Where is the physical location of the ballast resistor on the Red with light green trace wire?
 

2) Is the contact development of the ignition switch as shown on the Ford wiring diagram?  Does the red with light green trace only get +12 in the on position and not the start?

I’d get out a meter and answer some of these questions myself but I have the column and harness completely apart.

I’ll get this puzzle worked out one of these days...

Thanks for your time,

Peter

 

 

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1. Within the underdash harness.

2. Red/green trace gets power when key is in RUN and CRANK positions.  In CRANK position, only the Run-only lines and the red/blue wire for the wire going to the starting solenoid get power; ACC power is cut off during CRANK.

If you need RUN-only power, you can get it in the engine compartment by looking for a red/orange hash wire at the engine gauge feed harness (72, 73) that feeds the carb anti-stall solenoid and on the green/red wire that goes to the alternator (ammeter cars only). 

Let me check your shorts!

http://midlifeharness.com

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Thanks Midlife!

Adding some pictures to make the post mo betta...

It looks like the +12v to the Red with light green trace ignition wire is coming from two different sources. Run power is coming from the ignition switch and the Crank power is coming from the starter solenoid. 

I’m going to have to cobble something up so that the MSD box has power in both the Crank and Run positions.  

I’m trying to confirm that the ignition switch does not also power the circuit in the Crank.  If it does fantastic- if not I’ll have to add an aux relay of some sort.
 

 

0242E10B-7F34-46E3-9F75-FC7629999B6B.jpeg

6C94FD77-077C-4E5B-BD26-0E0474CFBED3.jpeg

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This should help clarify it, from Volume 3, section 33-71, of my '71 shop manual. It shows which contact/wire receives power in each ignition switch position.

Ignition Switch Continuity.JPG

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“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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  • 1 month later...

Going to piggyback this thread. Using that same diagram to the ignition switch mine has the not so pink, but faded pink that says "resistance" wire tapped into the Red with Light Green wire. plug. I'm not setting up an ignition box, but I am going to run a Petronix Flamethrower ignition 3 coil that will need a supply of 12V. 

1. Do I need to keep that pink wire? 

2. can i splice into the red green wire here directly? if so, what about the opposite end of with the 90DEG boot? or like OP find another source of 12V to connect directly to the coil? 

IMG_5347.JPG

1972 Mach1 H-code 351C - 2V - bought 10/5/2010 still a headeache

1972 Grande coupe Inline 6 1bbl - dad bought in 90's Sold

 

 

 

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The cleanest way to do it, and not have to run another wire through the firewall, is to use the Pertronix relay to power the coil directly from the battery, use the red/light green wire to the coil to trigger the relay.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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The yellow boot (red & light green wire) is the same as the i terminal on the solenoid And it’s hooked to the coil (+) and the red white is to the negative (-) with the black wire as the igniter. So... if I’m understanding you’re saying add/route an additional wire from the battery positive? Sorry electrical and wiring is not my forte. 

89E23D23-50DD-423E-87ED-C86FE635EAD2.jpeg

3C30700B-1BDD-4A5F-B1C1-CCCB71C9EFF6.jpeg

1972 Mach1 H-code 351C - 2V - bought 10/5/2010 still a headeache

1972 Grande coupe Inline 6 1bbl - dad bought in 90's Sold

 

 

 

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Remove the red/light green wire from the coil connect it to the trigger (small purple) wire on the relay, connect large red wire to battery, orange wire to the +side of the coil.

https://pertronixbrands.com/products/pertronix-2001-ignition-power-relay-kit?variant=31797256224804

Here's the instructions

https://cdn.shopify.com/s/files/1/0247/6913/4628/files/2001.pdf

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Oohhhhhh..... there’s a separate relay that needs to be purchased thanks pertronix for leaving that important detail out. On “easy plug and play”... :classic_dry:

1972 Mach1 H-code 351C - 2V - bought 10/5/2010 still a headeache

1972 Grande coupe Inline 6 1bbl - dad bought in 90's Sold

 

 

 

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it's not needed, if you bypass the resistor wire.

Are you sure you need to bypass the resistor wire? What is the part number of the coil you bought, or the primary resistance?

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Here's a couple of articles on automotive wiring that may help you

http://www.crankshaftcoalition.com/wiki/Automotive_wiring_101

The one in this thread is on Ford wiring and how to read the diagrams

https://7173mustangs.com/forums/topic/32456-how-to-read-wiring-diagrams/?tab=comments#comment-333558

 

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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PNX 44011 Flamethrower 3

PNX D7134620 igniter 3 distributor 

Im pretty certain I have to; I accidentally bought the flamethrower 2 and pertronix said it’s not compatible has to be the 3. And they were like it’s a simple plug and play.

1972 Mach1 H-code 351C - 2V - bought 10/5/2010 still a headeache

1972 Grande coupe Inline 6 1bbl - dad bought in 90's Sold

 

 

 

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Yes, the P3 requires full 12 volts. The instructions say to eliminate the resistor from the circuit. 

I doubt it you'll find any aftermarket electronic component that is truly plug & play for our cars, that's a term that has become misused for just about everything.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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So can I just pull it off the plug and tape it off?

1972 Mach1 H-code 351C - 2V - bought 10/5/2010 still a headeache

1972 Grande coupe Inline 6 1bbl - dad bought in 90's Sold

 

 

 

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No, the red/light green wire is what is used to trigger the relay, it is removed from the coil and connected to the purple wire on the relay.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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5 hours ago, Don C said:

No, the red/light green wire is what is used to trigger the relay, it is removed from the coil and connected to the purple wire on the relay.

I believe you meant that towards the comment if i had the relay. Im currently under the harness trying to figure out hat to do with this Resistor wire. my only option is to do the bypass. Reverting back to the original statement.  if the resistor wire shares the same terminal plug as the 12V Red Green wire, will this cause issues if i splice into that red wire?

Edited by kiko619
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1972 Mach1 H-code 351C - 2V - bought 10/5/2010 still a headeache

1972 Grande coupe Inline 6 1bbl - dad bought in 90's Sold

 

 

 

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You can tap into it any place before it changes into the resistor. You can then either tap back into the red/light green wire after the resistor or run the new wire out to the coil. If you use the new wire all of the way then the old wire connectors needs to be protected against shorting out.

Make sure the splices are done correctly, bad connections cause fires.

Rule #1, no household wire nuts

Rule #2, no twisted wire connections (soldered or crimped connectors only)

Rule #3, no wrapping connections with cheap electrical tape (self fusing tape or heat shrink tubing (waterproof preferred) only)

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“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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