Need Help in Identifying Location of Short

[shew01]

Originally Posted by cpf240

You said this was a rebuilt original ignition switch, yes? If so, not to be rude, but are you aware that it needs to be pushed in to be off?

Yes, the ignition switch is “in” (“off”) when the movable points arm reads .3 volts. When the ignition switch is “out” (“on”), the movable points arm reads 6 volts.

It seems the ignition is never really turning completely off.


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[shew01]

Originally Posted by The Master Cylinder

When the switch is off there is no power thru the armored cable.

That would appear to be my issue. There is always power coming through the armored cable (either .3 volts when ignition is “off” or 6 volts when the ignition is “on”).

Apparently, the coil is staying energized, which would account for the drop in battery voltage to roughly 1.5 volts in less than 24 hours.


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[shew01]

Originally Posted by Sunnybrook Farm

Do you have the armored cable that screws into the distributor, looks like a big spring?

Yes, it is an original popup ignition switch, rebuilt by Dick Crabtree.

Originally Posted by Sunnybrook Farm

first and easy to check is where it screws into the distributor, it could be screwed in too far and may push the lower plate against the body, it just needs to be tight enough to make good contact with the spring loaded plunger.

How can you determine if it is screwed in too far? I made an educated guess and screwed it in about 3 turns. It will screw 7 turns before it gets "tight."

Originally Posted by Sunnybrook Farm

Also there is a regular insulated wire that runs up that spring like case and that can rub and make contact.

That wire appears to be new.

Originally Posted by Sunnybrook Farm

The switch itself could have a break in the internal insulation that is leaking. I had an old original switch that actually got warm so I just got one at NAPA and use that since I don't plan on showing the car anymore.

The switch does not appear to get warm. Just the coil gets warm.

Originally Posted by Sunnybrook Farm

just switch back to your old switch to see if that is the problem

I thought about that, but I was hoping to find the issue without the headache of swapping out the cable twice more. Ultimately, I may not have much of a choice.

[shew01]

Originally Posted by Jim/GA

Do you have this book:

https://www.mafca.com/cart/index.php?productID=168

Look at the wiring diagrams and make sure you have the wires hooked up correctly.

You may have to open things up and take some pictures of how you have it all wired up, then post them here, for someone to help you spot the error.

Yes, I have that book. I took copious pictures before I took anything apart. I labeled the wires before removing them from the junction box terminals to check out Tom Endy's information about the screws that tend to short on the firewall. I think the wires are hooked up to the proper terminals.

[shew01]

Originally Posted by Ed in Maine

Last month I removed the instrument panel on my 31 Victoria and managed to create a short while putting in back in. In my case, the metallic covering on the dash lite wire had gotten up against one of the terminals of the ampere meter. I wrapped it with electrical tape in that area of the ampere meter terminal to solve the problem. Good luck, Ed

Prior to installation, I wrapped the ignition switch with tape to prevent any potential shorts. The ammeter does not seem to be grounding to the firewall. At the moment, I have the 4 instrument panel screws removed, and the panel is ajar from the dash. So, I don't think the ammeter is the issue (at least for now).

[shew01]

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Originally Posted by Gary WA

How old is Battery?Re-look at what you did to replace the items?

I don't know the age of the battery, but it charges back up to 6 volts if I turn "off" the power cutoff.

I'm still looking at what I did to replace the items. Nothing seems wrong yet.

[shew01]

Originally Posted by Big hammer

If you would have a short you would have a hot spot or smoke. If your having a draw down I would check the generator cut out to see if it is sticking closed. Remove the fan belt and see if the generator motors.

I should have mentioned that I have a 6 volt positive ground alternator. Would an alternator have a similar potential issue?

[Patrick L.]

Alternators have a slight parasitic draw, its part of their DNA.

[shew01]

Wow. I didn’t know that.


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[Sunnybrook Farm]

Over the years when I would find a survivor car, very few times was the original switch and cable in use, they seem to have been a weak point in the model A, just like the fan blade.

[Tom Endy]

Originally Posted by shew01

I should have mentioned that I have a 6 volt positive ground alternator. Would an alternator have a similar potential issue?

Alternators have a series of diodes in the output. A diode has a small amount of reverse current, it is not like a switch.

The same thing applies to a cutout that has been modified with a diode. If you leave the car sit for a month or so you will have a dead battery if power is applied.

I have a 6-volt positive ground alternator on my Victoria. A few years ago a diode failed and it kept running my battery down, even though it worked fine and put out power. I had to replace it.

The problem you are having is abnormal for a properly working alternator. It may be you have a failed diode in it. Disconnect the alternator and see if it resolves the problem.

Tom Endy

[shew01]

I think I’m narrowing this down. Here are my test scenarios.

Scenario 1:

- Key is removed. Rebuilt pop out switch is pushed in. Instrument panel screws are removed. Panel is away from inside of firewall to prevent possible shorts.



- Red wire is unscrewed from the side of the ignition cable.



- Points are held open with a popsicle stick. Negative lead of voltage meter is held to the movable point arm.



- Main power cutoff is “on,” and and the positive lead of the voltage meter is clipped to a bare firewall screw. No voltage goes to the movable point arm, as expected.



Scenario 2:

- All connections are the same, except the following.

- Red wire is screwed onto the side of the ignition cable.



- I now see .24 volts on the movable point arm.



- Insert the key. Turn “on” the ignition. Switch pops out.



- Movable point arm gets 6 volts, as expected.



- Press in pop out switch. Remove key.



- Movable arm still gets .27 volts.



What ideas do you have?


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[The Master Cylinder]

What you guys are saying could be true with his alternator. BUT, the diodes in the alternator has nothing to do with his coil being warm and him showing voltage at the points when the ignition switch is in the OFF position. I would investigate the switch farther.

[shew01]

Originally Posted by Tom Endy

Disconnect the alternator and see if it resolves the problem.

Tom Endy

I tested again with the alternator disconnected, but the results are the same with the ignition key “off” (“in”) and the red wire screwed to the side of the ignition switch.






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[Patrick L.]

With the alternator out of the equation I would then stick to the primary ignition circuit. Mainly the switch. As far as you are getting into this and once its figured out I'd recommend sticking the switch before the coil. Once your done with this you'll be the expert.

[Jim/GA]

Your restored pop-out switch is defective internally somewhere.

Contact the guy that sold it to you. Describe the problem you have. Ask him about getting another one from him.

[Jim/GA]

Originally Posted by Patrick L.

With the alternator out of the equation I would then stick to the primary ignition circuit. Mainly the switch. As far as you are getting into this and once its figured out I'd recommend sticking the switch before the coil. Once your done with this you'll be the expert.

Because of the way an original pop-out switch is designed, it cannot be installed before the coil, as you suggest. This is one of the downsides to Henry's original wiring scheme.

But he has a battery master cut-off switch, so that's always good.

[Patrick L.]

Originally Posted by Jim/GA

Because of the way an original pop-out switch is designed, it cannot be installed before the coil, as you suggest. This is one of the downsides to Henry's original wiring scheme.

But he has a battery master cut-off switch, so that's always good.

Really ? Hmm. OK. I guess I don't understand, but, thats OK. I don't use a pop-out and have not had an issue with one so I guess Ive never thought about it.

[The Master Cylinder]

What a waste of time. I told ya it was the switch back in post #16. I'm done.

[Jim/GA]

Originally Posted by The Master Cylinder

Sounds to me as if you have something connected incorrectly or your switch is BO and leaking thru. With switch off there should be zero voltage at the points, if you car is wired correctly.

Do you have any accessories wired into the ignition switch?

What does "your switch is BO" mean in plain English?