Keeps blowing fuse

[Model A Nick]

Hey guys,
Im about to give up on this thing. I had the engine compartment apart to paint and put it back together, started it and cause I had the wire on the starter instead of the fuse part, the wires burnt up. I ordered new wires and installed them per the wiring diagram. Everytime I turn on my cutoff switch the fuse blows. I followed the paper and the wiring diagram. Any ideas? I added pictures

[Jim/GA]

Brake light switch.

[Tom Wesenberg]

Your ammeter nut needs the black insulating cover, but for now it will probably have some clearance if you swap it with the other ammeter nut. Also make sure the small notch in the instrument panel, for the dash light wire, isn't cutting into the wire. The ammeter end of the dash light wire looks a little shaky also, so be sure it doesn't have a wire strand touching the conduit.

[Mitch//pa]

Everything ( the entire car) feeds from the junction box terminals... separate all your circuits there, then add them one at a time till the short comes back. Then youll know which direction to proceed using the diagram. . That being said also make sure the junction box stud / wire posts are not shorting out on the firewall very common..

[1955cj5]

I'd also disconnect the generator feed wire at the cut-out to isolate the headlight harness and light switch...

[MAG]

Sponsored Links (Register now to hide all advertisements)

Picture 2, Is that a shadow under the Red wire or is the short Black wire that should from from the connector box Driver side Post to Coil driver side (-)? If wired that way it looks, it will create a direct short through the ignition switch to the points in the dist. when they are closed and the fuse will blow.

[1crosscut]

I'm betting on the junction box studs grounding out against the firewall. Disconnect all the wires and using a voltage meter check for continuity between the studs and ground.

[Mike V. Florida]

Do what Mitch says. My guess is the dash light.

[Model A Nick]

OK, so I took it apart and started putting one wire at a time on to the box and the last wire shorted it out. The black striped one that goes to the cut out box on the generator. I have the headlights off the car, but I do have the end taped up separate from each other. I took the dash light wire off as well. I guess it needs the cutoff switch, or do the headlights need to be plugged in?

[Mitch//pa]

Do you have The yellow wires connected to the cutout terminal shown on the diagram? They feed the horn and light switch.. if so remove those and leave the yellow / black from the terminal box connected. If the short goes away keep following the diagram

A couple common sore spots are inside the light switch, stop light switch, and headlight connectors (but u mentioned those wires are taped up)

[Jim/GA]

Brake light switch.

[Growley bear]

As Jim Cannon suggested; Joining MAFCA and a local club will connect you with a wealth of information and some of the sharpest Model A people around.
Good luck

[Model A Nick]

OK, so I took the yellow wires off the cutout terminal and left the striped wire on, touched the striped wire to the junction block and it blew the fuse. So my guess is the cutout got messed up.

[Model A Nick]

Originally Posted by Growley bear

As Jim Cannon suggested; Joining MAFCA and a local club will connect you with a wealth of information and some of the sharpest Model A people around.
Good luck

I am a member of both clubs, just haven't joined a local chapter yet, as the closest one is a bit away. Once i get out there with it, I want too

[Mike]

I am a life member of the DELAWARE VALLEY MODEL A FORD CLUB BASED In BENSALEM PA . We meet th first Thursday of each month

[BILL WILLIAMSON]

Sometimes the terminal screws on the cut-out are TOO long & ground out on the generator case. Remember, most good terminal pliers have a cutter, to shorten many standard sized screws.
Bill W.

[Model A Nick]

Originally Posted by Mike

I am a life member of the DELAWARE VALLEY MODEL A FORD CLUB BASED In BENSALEM PA . We meet th first Thursday of each month

It meets in bensalem? That's really close to me, would love to go to one

[Tom Wesenberg]

Stop blowing good fuses and just connect a test light, or 6 volt buzzer across the fuse terminals. When the light goes out you have found the short.

[Mitch//pa]

Well you eliminated the lighting / horn circuit ,,incld the brake light switch. Your cut out may have a bad insulator which is causing it to ground through to the case. I use the diode cutouts that the suppliers sell,, no moving parts to hang up. Read up on what a cutout does and how it operates using the search feature, its a very simple device. Others prefer the original style with moving parts. The engine can be ran without one just connect the two wires together and bypass it... remember to disconnect those two wires after shutting down or youll have a draw through the generator which will drain the battery....

Plus what tom mentioned above,,,, this should have been stated earlier... a testlight works good

[Model A Nick]

Thank you for all your help!

[Patrick L.]

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.

[Tom Wesenberg]

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.

[cpf240]

Originally Posted by Tom Wesenberg

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!

[Mitch//pa]

Originally Posted by Tom Wesenberg

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

[BILL WILLIAMSON]

Originally Posted by Mitch//pa

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.
KDad

[Patrick L.]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by Tom Wesenberg

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.

[Mitch//pa]

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...

[Mitch//pa]

Originally Posted by BILL WILLIAMSON

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

[BILL WILLIAMSON]

Originally Posted by Mitch//pa

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!
KDad

[jm29henry]

Did you get it fixed?

[Model A Nick]

Originally Posted by jm29henry

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.

[denniskliesen]

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.

[Growley bear]

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

[Model A Nick]

Originally Posted by Growley bear

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!!

[Growley bear]

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.

[jrelliott]

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.

[Model A Nick]

Originally Posted by jrelliott

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

[1955cj5]

Now you have a spare!

[Growley bear]

Great job; Lesson learned.

[Patrick L.]

I am my own worst enemy sometimes
end quote


Hmm, aren't we all. We all have our brain farts every now and again.