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i'm just going over some stuff on my recently purchased 67 coupe 289 automatic and replacing little parts here and there for peace of mind and came across the solenoid. it looks old and im sure it works fine. the car starts and runs fine but i noticed this black wire that was tucked away near it. its crumbling apart and looks like it hasn't been being used. i'm assuming it goes into the solenoid but there isn't a connection for it. i look at other pictures online and there is two connections. mine just has the one on the right for the red wire.. so.. do i need it? solenoids i look to order online all have the two connections. if i get one, does this wire plug to it?
745049
 

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The positive wire going to your coil is powered via a resistance wire between the ignition switch and the firewall. This lowers the voltage going to the coil. Its done this way because points survive longer running on less than 12V.
While cranking to start the car, that brown wire, bypasses the resistance wire, and supplies 12V to the coil, which makes it easier to start. After starting, it reverts to being powered via the resistance wire.
 

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The positive wire going to your coil is powered via a resistance wire between the ignition switch and the firewall. This lowers the voltage going to the coil. Its done this way because points survive longer running on less than 12V.
While cranking to start the car, that brown wire, bypasses the resistance wire, and supplies 12V to the coil, which makes it easier to start. After starting, it reverts to being powered via the resistance wire.
so.. i don't need it? i should cut it and toss it?
 

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Huhh?? Didn't mean to imply that it was unnecessary .... it makes starting the car easier.
It looks like when the last solenoid died, it damaged the solenoid to starter cable. I'd be replacing that.
When you replace your solenoid, be sure to search here for the best brand. Many don't survive the first coupla starts.
 

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Discussion Starter #5
Huhh?? Didn't mean to imply that it was unnecessary .... it makes starting the car easier.
It looks like when the last solenoid died, it damaged the solenoid to starter cable. I'd be replacing that.
When you replace your solenoid, be sure to search here for the best brand. Many don't survive the first coupla starts.
so leaving it out makes the car start easier? i just couldn't figure out where it plugs into. theres no spot for it on this solenoid. it looks like it hasn't been used ever. looking at the age of it and the missing post. makes me wonder if this one is even correct for this car when comparing to others. if i get a new one, does this wire plug into the front left post next to the red wire?
 

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so leaving it out makes the car start easier? i just couldn't figure out where it plugs into. theres no spot for it on this solenoid. it looks like it hasn't been used ever. looking at the age of it and the missing post. makes me wonder if this one is even correct for this car when comparing to others. if i get a new one, does this wire plug into the front left post next to the red wire?
This solenoid is not original / correct for your 67. An original solenoid has an "S" terminal (left post, red-blue wire) and an "I" terminal (right post, brown wire). The "I" terminal exists to increase voltage to the ignition coil during cranking. Original coils don't operate on full battery voltage, they operate on lower voltage to prevent burning up the ignition points. The lower voltage is provided by a resistor wire from your ignition switch. When you crank the engine voltage will drop further because of the starter motor. The coil still needs to be able to create a good spark when you crank the engine. Therefore the "I" terminal feeds full battery voltage to the coil during crank. I assume on your solenoid you only have the "S" terminal, maybe the solenoid is from a newer car. I suggest you try to check where the other end of this orphaned wire connects to, it should ultimately and up at the ignition coil. And you should get a correct solenoid.
 

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Does the car have an original points type ignition system? If not, it may have been changed to an ignition system system that didn't require the reduced voltage, and a modern three terminal solenoid was employed.
 

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You have a solenoid for a Ford product with EEC-IV or newer that doesn't utilize an ignition resistance wire. If you have a "stock type" ignition coil you'll want to replace the solenoid and reconnect the brown wire to make starting easier.
 

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As implied in post #8, a stock solenoid had 4 terminals; one cable from the battery to the solenoid, a cable going out to the starter, the S terminal that powers the solenoid, and the I terminal that goes to the ignition coil. The loose wire you show would normally go to the I terminal. You may have an aftermarket ignition system that doesn't need the I terminal, or they just ignored it. What the I terminal does is provide 12v to the ignition coil when cranking. This gives the coil more power and makes it easier to start. When the key is released, the starter solenoid opens, the starter stops spinning and the coil no longer gets 12v from the I terminal. Power to the coil must go through the resistor wire which lowers the voltage to the coil. The coil will run cooler at the lower voltage and the points will last longer. Following is a schematic for a 69, but all the classics work the same way:
 

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Discussion Starter #12
i know i have a points ignition. my coil only has two wires connected to it. from the gauge feed wires and to distributor. and the big one in the middle. i know the previous owner installed a new ignition in the dash where the key goes. not sure what else was done as far as ignition goes. i was thinking of upgrading to the pertronix ignition system since i have to replace my points and condenser anyway and i was told the pertronix system is better. would i still need that brown wire if i did that upgrade?
 

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so leaving it out makes the car start easier? i just couldn't figure out where it plugs into. theres no spot for it on this solenoid. it looks like it hasn't been used ever. looking at the age of it and the missing post. makes me wonder if this one is even correct for this car when comparing to others. if i get a new one, does this wire plug into the front left post next to the red wire?
so.. i don't need it? i should cut it and toss it?
No, the wire is important. It is your solenoid that should be tossed. It is totally incorrect for any 65-73 Mustang. Heck, yours is even installed upside down.
 

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Replace it with a quality Standard or Motorcraft part. Parts store cheapies fail within minutes.

 

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i know i have a points ignition. my coil only has two wires connected to it. from the gauge feed wires and to distributor. and the big one in the middle. i know the previous owner installed a new ignition in the dash where the key goes. not sure what else was done as far as ignition goes. i was thinking of upgrading to the pertronix ignition system since i have to replace my points and condenser anyway and i was told the pertronix system is better. would i still need that brown wire if i did that upgrade?
OK, so you have a new ignition switch. Have you taken the distributor cap off and looked to see if you have points? The points are in the middle on the right side of the picture
745075
 

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i know i have a points ignition. my coil only has two wires connected to it. from the gauge feed wires and to distributor. and the big one in the middle. i know the previous owner installed a new ignition in the dash where the key goes. not sure what else was done as far as ignition goes. i was thinking of upgrading to the pertronix ignition system since i have to replace my points and condenser anyway and i was told the pertronix system is better. would i still need that brown wire if i did that upgrade?
There is a huge amount of information on this website about how to connect a Pertronix. Much of it was generated because people don't understand the ignition wiring. Here are 500 threads:
Pertronix Wiring?
 

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Discussion Starter #17
OK, so you have a new ignition switch. Have you taken the distributor cap off and looked to see if you have points? The points are in the middle on the right side of the picture View attachment 745075
yes, thats what i have. but i will be upgrading to the pertronix electric ignition. does the wiring for the solenoid need to be wired differently? do i still need that wire shown in my picture? i just wasnt sure if i needed it or not since it was disconnected this whole time and i didnt notice
 

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Yes, thats what I have. but I will be upgrading to the Pertronix electric ignition. Does the wiring for the solenoid need to be wired differently? Do I still need that wire shown in my picture? I just wasn't sure if I needed it or not since it was disconnected this whole time and I didn't notice.
The basic Pertronix I requires no special wiring. The two leads from the unit connect to the (+) and (-) terminals on your coil.

The disconnected status of that wire on your car simply made it a bit harder to start.
 

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Discussion Starter #19
The basic Pertronix I requires no special wiring. The two leads from the unit connect to the (+) and (-) terminals on your coil.

The disconnected status of that wire on your car simply made it a bit harder to start.
its still disconnected. i dont have any starting issues. theres no place on this solenoid to connect it to. i guess i'll plug it into the new one i get and see if it makes any difference.
 

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its still disconnected. i dont have any starting issues. theres no place on this solenoid to connect it to. i guess i'll plug it into the new one i get and see if it makes any difference.
Well, it's not too hard to start a car right now. If the snow were up to the door handles you might have a problem…
 
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