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03-16-2020, 06:34 PM | #1 |
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Which wire is positive/negative for ignition coil?
This maybe a dumb question...but which of these two wires is negative and which is positive for the ignition coil? I’m replacing my old coil and noticed that the wire which stems from a stud on firewall was on the positive and that the red wire which seems to go through firewall to gauge cluster was on negative? This doesn’t seem right, but the car has been running and driving with that wiring? That being said...it’s been running rough which I’ve been trying to diagnose. Let me know, thanks!
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1931 Ford Model A Tudor Complete stock rebuild Disregarding the constabulary since 1931 |
03-16-2020, 06:48 PM | #2 |
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Re: Which wire is positive/negative for ignition coil?
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Last edited by Sparta; 03-16-2020 at 06:57 PM. Reason: wrong photo |
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03-16-2020, 06:48 PM | #3 |
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Re: Which wire is positive/negative for ignition coil?
Stock wiring/positive ground? Wire from junction box to - and Red wire from ignition switch +.
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03-16-2020, 06:55 PM | #4 |
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Re: Which wire is positive/negative for ignition coil?
okay, in that case i had it wired with opposite polarity. would it be possible for the car to run in that manner?
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1931 Ford Model A Tudor Complete stock rebuild Disregarding the constabulary since 1931 |
03-16-2020, 07:03 PM | #5 |
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Re: Which wire is positive/negative for ignition coil?
It depends on the battery ground. The ignition system is grounded thru the points so the wire to the distributor is wired the same as the battery ground.
Yes, the car will run fine [ usually] with the points/coil wired 'backwards'. |
03-16-2020, 07:10 PM | #6 |
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Re: Which wire is positive/negative for ignition coil?
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1931 Ford Model A Tudor Complete stock rebuild Disregarding the constabulary since 1931 |
03-16-2020, 09:01 PM | #7 |
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Re: Which wire is positive/negative for ignition coil?
There are hundreds of different coils and very few cars are wired alike, so it is almost impossible to tell for sure by just looking at it. order a polarity tester from one of the vendors then you will know.
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03-16-2020, 10:01 PM | #8 |
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Re: Which wire is positive/negative for ignition coil?
Always remember the points are to ground, so if positive ground car, as original, the red wire , which goes thru the key switch to the points is the ground. If 12v neg ground, the. The black wire goes to the switch to points
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03-17-2020, 06:05 AM | #9 |
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Re: Which wire is positive/negative for ignition coil?
This may help: http://www.chicagolandmgclub.com/tec...neral/574.html
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03-17-2020, 08:21 AM | #10 |
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Location: Largo Florida
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Re: Which wire is positive/negative for ignition coil?
The polarity tester like 1930 coupe showed is a good thing.
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03-17-2020, 08:23 AM | #11 |
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Re: Which wire is positive/negative for ignition coil?
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03-17-2020, 08:39 AM | #12 |
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Location: San Antonio, Texas
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Re: Which wire is positive/negative for ignition coil?
A coil that is connected with the wrong polarity will not work at its max potential. Polarity is important. A pencil can be used to check polarity but the Nu-Rex tool in post 7 is easier to use with no possibility of shocking the operator.
The weakest point in the model A ignition system is the condenser. It won't work well at all if the condenser is bad. |
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