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1967 - 1972 F-100 & Larger F-Series Trucks Discuss the Bumpsides Ford Truck

Alternator Gauge Testing

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Old Dec 15, 2018 | 12:21 PM
  #1  
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Alternator Gauge Testing

The alternator gauge in my 1971 F250 is not working (no movement) while starting, with light on & motor not running. I had the stock 65 or 95 amp alternator tested & it works fine. All other gauges work as they should.

Is there any way to test the gauge? If the gauge tests OK I would think problem is in the wiring.
Just trying to eliminate one thing at a time.
 
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Old Dec 15, 2018 | 01:30 PM
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Remove the cluster from the truck. Hook jumper wires to each post on the alternator gauge. Touch the other end of the wires to an almost dead 1.5 V battery, like a AA size. If the gauge is good, the needle will swing one way, maybe full scale, depending on how dead the battery is. Reverse polarity & the gauge will swing the opposite direction. Do this for just a couple of seconds. If the gauge doesn't work, clean the studs & nuts & try again. Out of 40 or more of this style gauge I've only had a couple of bad ones.

These alternator gauges work on very low voltage, over time corrosion on the printed circuit, gauge studs, cluster plug, & the rest of the wiring will render them inoperative. Clean everything to spotless & the gauge will work for a little while until corrosion comes back.

There is a company that converts the Alt gauge to a volt meter, that may be the best fix.
 
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Old Dec 15, 2018 | 09:01 PM
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Scottscott --- Thanks for the information on the Alternator Gauge, I will go through the items one by one after the Holidays and see what I come up with. I would like to convert the OEM gauge to a Voltage Gauge as soon as I can. I think they can make my gauge into a Volt gauge even if it is not working. The one company I say last year leaves the original alternator face plate with about 13 volt reading at the middle between (-) & (+).

Do you know of a place that does this change? I have a new aftermarket volt gauge but I want to stay with the original style setup.
 
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Old Dec 15, 2018 | 09:34 PM
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Here is a link to the site that does them for the 80's trucks
http://www.rccinnovations.com/index....enu-trucks-all
Dave ----
 
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Old Dec 16, 2018 | 04:27 AM
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Originally Posted by FuzzFace2
Here is a link to the site that does them for the 80's trucks
http://www.rccinnovations.com/index....enu-trucks-all
Dave ----
Thanks for that web site link FuzzFace2. I didn't know that if the old tachs went out that it would disable the ignition.
 
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Old Dec 17, 2018 | 03:28 PM
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FuzzFace2 --- Thanks for the website information, I had their stuff but I misplaced it. They will do a alternator to volt change to my 1971 unit for around $45 + shipping ($15). They list the part number under F100. I am going to email him to make sure he can still do my year gauge and check on price. He is a good guy, one man shop & price is right.
 
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Old Dec 17, 2018 | 11:35 PM
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That's a very reasonable price it sounds like. In the interim, there are small digital volt-meters that plug into the cigar lighter sockets and can give you a nice readout (as long as you don't need the socket!) when you need it.
It's not really meant to be a permanent thing on older vehicles, because not everybody is going to like the digital readout near their nice old analog gauges. But as a diagnostic tool, or in the case of a failed ammeter, a temporary monitor, they're hard to beat.

Paul
 
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Old Dec 18, 2018 | 03:24 AM
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Originally Posted by 1TonBasecamp
That's a very reasonable price it sounds like. In the interim, there are small digital volt-meters that plug into the cigar lighter sockets and can give you a nice readout (as long as you don't need the socket!) when you need it.
It's not really meant to be a permanent thing on older vehicles, because not everybody is going to like the digital readout near their nice old analog gauges. But as a diagnostic tool, or in the case of a failed ammeter, a temporary monitor, they're hard to beat.

Paul
Do you know who carries them?
 
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Old Dec 18, 2018 | 12:04 PM
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Well, we used to!
I was going to say we had them, but noticed they're not on our site anymore (https://www.wildhorses4x4.com/catego..._Dash_Switches) which is not a good sign!
Usually that means that whoever we were getting them from is having a hard time supplying them.

On that page I linked to, the #7053 is similar looking to what we had. Just that it had the usual plug insert to fit into a cigar lighter, instead of just a face to go into a hole like the one shown is.
Maybe the usual suspects, such as Summit or wherever has some?

I'll do a little checking too, but now you know what to look for. I'm sure there are some out there still, since it's such a great tool.

Paul
 
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Old Dec 18, 2018 | 02:52 PM
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You can find them on Ebay, I saw two, less than $5 china junk but OK for a short term reading.

Checked my lighter switch operation & it does not work. Will have to check out power into the unit.

Thanks Paul, handy little tester to have in tool box.
 
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Old Dec 18, 2018 | 03:06 PM
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My thinking exactly. Same way I felt about the cheesy-looking Thermostat Radiator Caps that Mr Gasket brought out about 11 years ago or so.
Kind of looked cheap, but if was even remotely accurate it could be utilized for under-hood readings while working on the engine. Nice to do without having to run an additional gauge, or keep going back to the cab to peek at the existing gauges.

Then again, I always liked the idea of a little gauge pod for under-hood use that could be quickly connected to use only while working under the hood.
That way you could have all the parameters covered.

Paul
 
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Old Dec 18, 2018 | 10:03 PM
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For anyone thinking of installing a 3G alternator in a early model Ford you should pick up the latest issue of Hot Rod Magazine, they have a very complete article on the conversion with suppliers for connection parts. They also show a chart of Ford 1G-60 amp, 2G-75 amp, 3G-95 amp, 3G-130 amp, 3G-200 amp output, very informative.
 
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