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Old 03-25-2017, 01:03 PM   #21
Patrick L.
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Default Re: Keeps blowing fuse

A test light and wiring diagram are invaluable, about the best money you'll spend.

Sometimes the cutout terminal screws are a tad too long and will ground against the generator case. Just another place to look along with all the other good info.

Once you get into the headlight connectors, they are another place to be mindful of shorts. I tend to do away with those pesky little connectors.
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Old 03-25-2017, 02:36 PM   #22
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Default Re: Keeps blowing fuse

There is another way to test for shorts without having to take anything apart. This is especially good for newer cars with more complex wiring. You clip a flasher and light bulb (in series) across the two fuse terminals. The short will make the bulb flash on and off. Then just take an inductive ammeter or compass and lay it along the wires. The needle will flicker until you go past the short.
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Old 03-25-2017, 02:48 PM   #23
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Default Re: Keeps blowing fuse

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There is another way to test for shorts without having to take anything apart. This is especially good for newer cars with more complex wiring. You clip a flasher and light bulb (in series) across the two fuse terminals. The short will make the bulb flash on and off. Then just take an inductive ammeter or compass and lay it along the wires. The needle will flicker until you go past the short.
Interesting idea... have not heard of that one!
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Old 03-25-2017, 02:55 PM   #24
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Default Re: Keeps blowing fuse

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Originally Posted by Tom Wesenberg View Post
There is another way to test for shorts without having to take anything apart. This is especially good for newer cars with more complex wiring. You clip a flasher and light bulb (in series) across the two fuse terminals. The short will make the bulb flash on and off. Then just take an inductive ammeter or compass and lay it along the wires. The needle will flicker until you go past the short.
The needle will also point towards the short, showing you which way to follow the circuit. When you pass the short it will point in the opposite direction
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Old 03-25-2017, 07:45 PM   #25
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The needle will also point towards the short, showing you which way to follow the circuit. When you pass the short it will point in the opposite direction
I have an OOOOLD Snap-On meter for that purpose, it came with a dandy circuit breaker.
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Old 03-25-2017, 07:45 PM   #26
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Quote:
Originally Posted by Tom Wesenberg View Post
There is another way to test for shorts without having to take anything apart. This is especially good for newer cars with more complex wiring. You clip a flasher and light bulb (in series) across the two fuse terminals. The short will make the bulb flash on and off. Then just take an inductive ammeter or compass and lay it along the wires. The needle will flicker until you go past the short.




Works well. Even thru body panels.
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Old 03-25-2017, 07:55 PM   #27
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Default Re: Keeps blowing fuse

My inductive meter has to be pretty much touching the harness to register.. i have an ultrasonic device that i use for going through panels , rugs etc...
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Old 03-25-2017, 07:57 PM   #28
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I have an OOOOLD Snap-On meter for that purpose, it came with a dandy circuit breaker.
KDad
Maybe you can post a pic of that... i would like to see it

It might be in your safe if you cant find it
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Old 03-26-2017, 10:07 AM   #29
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Maybe you can post a pic of that... i would like to see it

It might be in your safe if you cant find it
I can't get to the garage to "discover" it
At one time, Snap-On discontinued them, as the circuit breakers were mal-functioning & burning up LOOMS!
Once we were creating SHORTS, when screwing roof racks on Datsun wagons, a screw would penetrate the flat roof loom. We'd just run the circuit breaker for awhile & feel for a WARM screw head, take the screw out & NIP it shorter. I told you we were GOOD!!
We also created SHORTS when nailing down the carpet panels, with them SCREW TACKS! There was also a flat loom beneath them.
A new Guy installed a rack, TOO FAR back & the tailgate wouldn't open all the way, BOY, he wuz in HOT WATER!
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Last edited by BILL WILLIAMSON; 03-26-2017 at 10:19 AM.
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Old 03-26-2017, 11:27 AM   #30
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Default Re: Keeps blowing fuse

Did you get it fixed?
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Old 03-27-2017, 07:21 AM   #31
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Did you get it fixed?
I have it traced to the cutout, so a new one should be here tomorrow. Its like this car just wants to sit in the garage. I take one step forward and then 3 steps back.
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Old 03-27-2017, 09:52 AM   #32
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Default Re: Keeps blowing fuse

Check the terminals on your key switch. The harness I bought from one of the vendors had terminals that were too long from the ring hole and the insulation. The wire terminal was grounding out on the case of the key switch.
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Old 03-27-2017, 10:09 AM   #33
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I don't know what amount of experience you have in the realm of automotive
service/maintenance. Electrical service and trouble shooting seems to be a hard one for lots of folks. It need not be though.
The main rule is to take the time to educate yourself about the way something works. If you don't know how it works, you can't fix it; if you do, it was an accident.
There are many people in MAFCA & RORD BARN who are very knowledgeable and there is usually someone in a local club who is willing to help.
The best approach to your problem is to check everything that you disturbed while working on the car. You are on the right track by checking one thing at a time. It seems odd that if the cutout was operating properly that it would develop a short without some outside help. Usually when the contact points stick in the cutout, the ammeter shows a distinct discharge and draws the battery down. As with all things mechanical though there is always the exception.
Do you have a wiring diagram? The model A diagram is easy to follow with just a basic understanding of automotive electricity and schematic symbols.
It ain't rocket science and if your Model A is close to bone stock your problem is probably is nothing new; except maybe to you.
Sorry for the dissertation, just trying to help.
Good luck and keep us posted
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Old 03-28-2017, 07:13 AM   #34
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Default Re: Keeps blowing fuse

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Originally Posted by Growley bear View Post
I don't know what amount of experience you have in the realm of automotive
service/maintenance. Electrical service and trouble shooting seems to be a hard one for lots of folks. It need not be though.
The main rule is to take the time to educate yourself about the way something works. If you don't know how it works, you can't fix it; if you do, it was an accident.
There are many people in MAFCA & RORD BARN who are very knowledgeable and there is usually someone in a local club who is willing to help.
The best approach to your problem is to check everything that you disturbed while working on the car. You are on the right track by checking one thing at a time. It seems odd that if the cutout was operating properly that it would develop a short without some outside help. Usually when the contact points stick in the cutout, the ammeter shows a distinct discharge and draws the battery down. As with all things mechanical though there is always the exception.
Do you have a wiring diagram? The model A diagram is easy to follow with just a basic understanding of automotive electricity and schematic symbols.
It ain't rocket science and if your Model A is close to bone stock your problem is probably is nothing new; except maybe to you.
Sorry for the dissertation, just trying to help.
Good luck and keep us posted
I was the outside help, LOL! it was def pegged to the discharge when it was running, so the cutout should be here today and I will hook it up one wire at a time. I hope I can finally put it all back together and start enjoying it. Thanks!!
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Old 03-29-2017, 10:33 AM   #35
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Default Re: Keeps blowing fuse

Did you try bypassing the cutout? You can do that with a jumper wire 10/12 ga. Don't run the engine with the generator disconnected, no need of that.
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Old 03-29-2017, 11:28 AM   #36
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Default Re: Keeps blowing fuse

Let us know if the new cutout worked. Again look to see if the screw on the cut out terminal feeding the car is touching the case of the generator.
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Old 03-29-2017, 12:50 PM   #37
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Let us know if the new cutout worked. Again look to see if the screw on the cut out terminal feeding the car is touching the case of the generator.
I am my own worst enemy sometimes, the new cutout did not work as i had the bolt,rubber washer, then the wire against the cutout. So once i looked at my pictures and after pulling my hair out, I put the wire the correct way, bolt, wire then washer, everything worked as it should. And there was nothing wrong with the original cutout
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Old 03-29-2017, 01:25 PM   #38
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Default Re: Keeps blowing fuse

Now you have a spare!
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Old 03-30-2017, 07:40 AM   #39
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Great job; Lesson learned.
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Old 03-30-2017, 08:22 AM   #40
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I am my own worst enemy sometimes
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Hmm, aren't we all. We all have our brain farts every now and again.
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