Model A shorting out

[Sovereign1]

Hi, I just restored the engine and ran a new wiring harness and everything was good for awhile but now (sometimes) when I turn the lights on, the ignition shorts out and the engine quits... Any thoughts?

thx

Doug

[Rob Doe]

Do you have a safety fuse at the starter switch?

Does it blow?

What does the ammeter show?

Tom Endy has an article at www.santaanitaas.org/ that will walk you thru the logical process step by step to find your fault or at least narrow down which part of the electrical system the trouble is in.

[Banditorama]

Are the bulbs blowing?

Try removing the bulbs and seeing if it still happens. If it does, then it's the switch itself.

If not, take a multimeter and test for high resistance on any of the wires that run to and from the switch

[Bill G]

Often the connectors at the base of the headlights have issues (If you have kept it original). To confirm this is the case, you can disconnect each light separately to determine which one and go from there. You will find that owning a Model A involves a lot more hands on than modern cars.



Originally Model A's did not have a main fuse. If you do not already have a fuse installed, you should really get one from one of the vendors. Inexpensive and easy to install. Fuses are one heck of a lot cheaper than burning out wires and having to buy a new harness all over again.

[Ruth]

Originally Posted by Bill G

Often the connectors at the base of the headlights have issues (If you have kept it original). To confirm this is the case, you can disconnect each light separately to determine which one and go from there. You will find that owning a Model A involves a lot more hands on than modern cars.

Originally Model A's did not have a main fuse. If you do not already have a fuse installed, you should really get one from one of the vendors. Inexpensive and easy to install. Fuses are one heck of a lot cheaper than burning out wires and having to buy a new harness all over again.

What Bill G said.

[lrf]

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I had a similar problem years ago, found out that a headlight adjusting screw was turned in too far touching the socket wires. LRF

[GPierce]

Originally Posted by lrf

I had a similar problem years ago, found out that a headlight adjusting screw was turned in too far touching the socket wires. LRF

I had that same problem last week.

[David in San Antonio]

I also had the screw too far in. Another potential source of short circuit is the little metal slugs in the socket which touch the bottom of the bulb. If a slug is sticking out too far from the socket it can get cocked sideways and short against the socket when you twist the bulb. Try gently pulling on the wires to draw the slugs lower in the socket until you twist in the bulb. This is what I was told but have not tried it myself.

[ronn]

I had the ammeter wires on the back of the dash shorting against the tank.


never liked that set up.

[tucan31]

Install a fuse. Remove all the bulbs, with a multi-meter check for a continuity (short to ground) on all wires. For example on a tail lamp there should be no continuity between the green wire and body, no continuity between the black wire and body, etc.