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Old 07-23-2016, 02:20 PM   #1
dbrist
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Default 12v wiring diagram

I've been searching these threads for a while and I might have missed it, but I was wondering if anyone had a 12v negative ground wiring diagram
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Old 07-23-2016, 03:02 PM   #2
Gary WA
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Default Re: 12v wiring diagram

No but in the Model A For Mechanics Handbook Vol. 2 shows it all.
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Old 07-23-2016, 03:05 PM   #3
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Default Re: 12v wiring diagram

Thanks ordered it a month ago and still waiting
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Old 07-23-2016, 03:09 PM   #4
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Default Re: 12v wiring diagram

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Originally Posted by dbrist View Post
Thanks ordered it a month ago and still waiting
also How to restore your Model A. Vol 8 has info too.
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Old 07-23-2016, 05:22 PM   #5
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Default Re: 12v wiring diagram

Only difference between 6V positive ground schematic and 12V negative ground schematic is the polarity of the battery. Just have to repolarize the generator after changing the battery connections if you are going to use the same generator. Make sure you have negative ground alternator if using an alternator. The electrons do not care which way they travel. They just move from negative to positive.
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Old 07-23-2016, 06:08 PM   #6
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Default Re: 12v wiring diagram

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Trucks already 12v system just like schematics to trouble shoot with
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Old 07-23-2016, 06:54 PM   #7
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Default Re: 12v wiring diagram

Use this just switch the battery polarity around on the schematic
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Old 07-23-2016, 10:50 PM   #8
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Default Re: 12v wiring diagram

Quote:
Originally Posted by dbrist View Post
I've been searching these threads for a while and I might have missed it, but I was wondering if anyone had a 12v negative ground wiring diagram
One only has to swap the wires on the ammeter and the coil to change the polarity.

To increase the voltage:

The coil needs to be changed or a ballast resistor added.
The horn needs a resistor or needs to be rewound.
Here is where we can get into a debate, one camp says leave the starter alone and the other says to have it converted to 12 volts. Take your pick.
Of course the bulbs have to be replaced.
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Old 10-03-2017, 09:55 PM   #9
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Default Re: 12v wiring diagram

im new..pls tell me the correct wiring for a 12V model A..what wires go where on coil?
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Old 10-04-2017, 12:20 AM   #10
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Default Re: 12v wiring diagram

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im new..pls tell me the correct wiring for a 12V model A..what wires go where on coil?
12v negative ground, battery positive to + side of coil, - side of coil to points (via switch). See Mike's post #8 above.

Last edited by Y-Blockhead; 10-04-2017 at 12:25 AM. Reason: Verbage...
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Old 10-04-2017, 05:28 AM   #11
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Default Re: 12v wiring diagram

Points are wired same as the battery. Whichever wire goes to ground from the battery goes to the points from the coil.
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Old 10-04-2017, 01:37 PM   #12
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Default Re: 12v wiring diagram

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im new..pls tell me the correct wiring for a 12V model A..what wires go where on coil?

The point to point wiring makes no difference what the voltage the battery is.
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Old 10-09-2017, 09:32 PM   #13
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Default Re: 12v wiring diagram

This is a complete discussion on converting to 12v as well as adding turn signals.

http://cedarcreekas.org/TechTopics/1...rn_Signals.pdf
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Old 06-24-2020, 08:25 PM   #14
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Default Re: 12v wiring diagram

I just made a 12v Negative Ground diagram after rewiring mine. This is a tried and tested diagram. Here is how you wire the ignition system. This diagram does not include lighting and horn.

NOTE: The Aftermarket "pop-out" style ignition cable connects to the "ON" position of the key switch. The "OFF" Position of the key switch connects to the NEG side of the coil. The key switch simply completes that circuit. DO NOT supply the "pop out" cable with 12v+!! Also in this diagram, you are looking at the BACK of the Ammeter where the studs are located. This diagram shows a GM 10Si one wire alternator, which self excites. Make sure you have a alternator that excites at LOW Rpm or it will not charge at idle. If you run a 3-wire alternator, DO NOT supply 12v constant to the exciter while the car is off. It WILL burn up!
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Old 06-24-2020, 09:26 PM   #15
marc hildebrant
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Default Re: 12v wiring diagram

30AModel,

You need to check your diagram as the ammeter is not connected and the alternator connects directly to the battery.

Marc
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Old 06-24-2020, 09:43 PM   #16
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Default Re: 12v wiring diagram

The ammeter is connected to the distribution block and the main alternator lead connects to the Positive post on the starter, which in turn feeds back to the battery.
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Old 06-25-2020, 09:51 AM   #17
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Default Re: 12v wiring diagram

Ammeter originally was wired to show only battery current in/out. 30AModel moved it to the load side; it shows only "charge" of the entire load (minus coil) from alternator and/or battery. (I suggest moving coil to other side of block so its current will register also.)
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Old 06-25-2020, 10:19 AM   #18
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Default Re: 12v wiring diagram

Quote:
Originally Posted by Mitch//pa View Post
Use this just switch the battery polarity around on the schematic
And the coil.
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Old 06-25-2020, 01:33 PM   #19
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Default Re: 12v wiring diagram

Don't forget to reverse the wires at the ammeter when changing polarity or the ammeter will read backwards .
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Old 06-26-2020, 01:44 PM   #20
Chuck Sea/Tac
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Default Re: 12v wiring diagram

Am I wrong?? The ampmeter has to have current flowing through it, or else how would it register current? If one side isn’t connected to anything, I fail to see how it would measure the current.
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