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Why rewire the ammeter this way?

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Old 01-18-2018, 11:08 PM
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Why rewire the ammeter this way?

I got a new/old shop manual today and still can not make heads or tails of why someone would have done this. The electrical diagram shows a ammeter in the P series but not the F series diagram, (Chapter 15-6). I fear the battery is not charging properly. I changed the generator front plate with a new one thinking it was the cause of not getting a positive reading on the meter, but no luck. That's when I started tracing the wiring from meter to solenoid to generator. The first time I started the truck after cleaning the generator I had a positive charge, erratic as it was it did bounce to the + side. I have nothing now.

The two red wires are connected to the opposite posts on ammeter.
Someone removed these from the solenoid and taped them together to one of the new red wires going to the ammeter.
Normal wiring here.
There is a 40 amp filter on the back of the generator I have not checked yet.
 
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Old 01-18-2018, 11:21 PM
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I forgot to mention, it's a 64 F100 Y Block 2WD Auto.
 
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Old 01-19-2018, 12:29 AM
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Tough to tell from here, but the noise filter on the generator doesn't look right, is it connected in series somehow? Pg 16-4 shows how suppression parts are to be installed.

Heavy yellow Armature wire should connect directly to terminal on generator in any case. I'd remove it (noise filter) for test purposes, since they tend to short out.
 
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Old 01-19-2018, 08:58 PM
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Didn't take the filter off yet, busy with shifter column and adjusting the valve lash today. But I did notice that when I started the truck the ammeter rose to a positive read then petered out back to zero after a couple seconds. Started the truck several times and got the same result. Will pull the filter tomorrow and try it again to see what I get.
 
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Old 01-20-2018, 05:40 AM
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Amps

Originally Posted by scoham64f100 View Post
Didn't take the filter off yet, busy with shifter column and adjusting the valve lash today. But I did notice that when I started the truck the ammeter rose to a positive read then petered out back to zero after a couple seconds. Started the truck several times and got the same result. Will pull the filter tomorrow and try it again to see what I get.
Sounds like what you are seeing is a normal condition if you have a good strong battery. Your wiring to the amp meter looks like it is wired the way Ford wired them except it is a little rednecked. You can clean all that up with a junction block and you really need a 70 amp breaker between that starter relay and the wire going to the ammeter. The picture is one with an alternator but same principle.
 
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Old 01-20-2018, 04:44 PM
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Thanks, I'll look for something that will replace/hide the electric tape connection and start shopping for a amp breaker. I should be able to hide the breaker in the cab under the dash.
 
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Old 01-23-2018, 01:26 PM
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After studying this for several days now, I've come to a clear understanding of how this 64 was wired originally. The 64 shop manual leave a lot to be desired in their wiring diagrams spread thru out the manual. Using a 65 wiring diagram for the charging system, (replace alternator and add a generator and voltage regulator), you get an accurate representation of the ammeter wiring in my 64. The 1964 shop manual does not have a whole page wiring diagram for the "ignition, starting and charging". Maybe this will help someone on the same learning curve with a 64 in the future.


This is the closest the 64 shop manual comes to the actual wiring.


 
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Old 01-23-2018, 01:58 PM
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Stock or correct ammeter?

The 65 diagram shows the loop thru on the ammeter. I checked the back of my ammeter to see how it was wired. There is no loop on the meter, it has two posts and a light in the center of it. Is this the 50 year old stock meter or has it been replaced. If replaced I would like to go back to the original gauge.


 
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Old 01-23-2018, 02:18 PM
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Well the housing looks correct I would guess it's a Ford gauge. When that gauge is installed all your power passes through the gauge. It should have a good quality #6 wire ran to it. That's the reason you need a breaker or fuse in that circuit. If something shorts out that thing can burn your truck up. I used a resettable breaker so I could use it as a disconnect when the truck is sitting for a long time. That way I can starve all the electrical vampires.
 
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Old 01-23-2018, 02:22 PM
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I think the loop you are seeing may part of the gauge. There is a copper strip inside the gauge that bridges between the two terminals. So be careful if you take it apart and don't let those studs turn or it will break.
 
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Old 01-23-2018, 03:41 PM
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I've read how useless these where with a lot of complaints of not being able to tell if they were even working while several Tech. bulletins were released to dealers on them. Until 1970 when they corrected the problem. It was an article under another website.

Ford Ammeter Gauges: Do They Work? | MILEPOSTS Garage (Tech Tips)

1967-1971 Ford Thunderbird and 1969-1971 Continental Mark III AMP Gauge Repair

If that's the case and this is an original, I'm thinking of sending off to be rebuilt. Found this site while researching the Ammeter. He wanted pictures of the front and back to get an idea of what we are dealing with.

Rocketman's Classic Cougar Innovations
 
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Old 01-24-2018, 05:39 AM
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I need to correct something I typed before, that wire should be a #8 not a #6. And I don't think these gauges were ever meant to be all that accurate they just let you know if you are charging or discharging. If you need to know exactly what the charging system is doing you would need some accurate test equipment. Just start the engine and bring the revs up to about 2000 rpm turn the head lights on and blow the horns if it doesn't show a big discharge your good to go.
 
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Old 01-24-2018, 09:22 AM
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I'm wondering if someone re-wired it or if someone added an ammeter to your truck that maybe didn't have one originally. Between the gauge and backing plate and red wiring hooked up the way it is I have a hunch....

On a side note - trucks with alternators in this era still had a separate voltage regulator. Integrated regulators built into the alternator didn't come around until a few years later.

Chad

.
 
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Old 01-24-2018, 12:47 PM
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If decide to install junction block, fuse block and or both might I suggest it not be placed under the dash?
 
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Old 01-25-2018, 12:01 AM
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Originally Posted by daveengelson View Post
If decide to install junction block, fuse block and or both might I suggest it not be placed under the dash?
2nd that. If the short is between the under dash fuse/breaker and the battery it'll still cook. If the fuse/breaker is closer to the power source there is less unprotected wire.
 
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