New one wire 12v conv on Farmall cub

Delig · Jul 26, 2023

I swapped out my old 12 v conversion with a one wire conversion because the wiring was a mess and wanted to clean it up. Unfortunately, after installing and trying to test for spark, i got sparks form the starter ignition switch and now it wont turn over. Is it possible that switch was 6v still?

I dont see how, considering its a direct line from the 12v battery in both setups.

Btw the one wire alternator runs to the ohmmeter the other pole runs to the starter/battery positive.

Steve@Advance · Jul 26, 2023

I suspect there is a bad connection somewhere.

A switch doesn't care if it is 6v or 12v, but an old switch may fail after being tampered with. A simple test light would be a valuable investment.

I assume you meant to say ampmeter, not ohmmeter. Yes, the wire from the alternator goes to the ampmeter, needs to be a 10 gauge wire.

Once you get it started, you will find the engine needs to be revved substantially to initiate the charge. Don't assume something is wrong if it does not charge.

Delig · Jul 26, 2023

Yea- ampmeter.
With my ohmmeter, I verify 12.6v at the starter switch, which is the same as testing the battery directly. That makes sense because Im testing where the positive lead connects.
is there a way I can test that switch to see if its trying to kick the starter?

John M · Jul 26, 2023

You shouldnt have voltage to the ignition switch since you have a mag. No connections at all to the mag except the one wire from the ignition switch. If the wire from the amp gauge is sparking when you connect it to the starter switch, then you have a short somewhere.

Steve@Advance · Jul 27, 2023

Put the volt meter from the starter post to the starter case, engage the switch, see if you have power to the starter post.

Also put the volt meter across the battery post and ground, engage the starter. If the voltage drops to near nothing, there is a bad connection upstream. Loose battery cable, bad ground, dead battery...

If the power drops and the cable heats up, the starter is jammed in the flywheel, or internally shorted.

Delig · Jul 28, 2023

before reading your reply because we were at the county fair yesterday.

This morning, I removed the secondary wire from starter to the ammeter and reconnected the positive to the battery which caused sparks indicating a short. I then replaced the older cake with a new 86 cable. When connecting the new cable only (no additional wires), I got a few sparks but not as many as with the old cable. I then pulled the starter to bench test and it actuates fine. is it possible there is a bad spot causing a short in the starter?
I took it for testing at Smyth(automotive)and was turned away because their digital system can't handle that starter model... so now I'm thinking, maybe I just replace the starter but I'm not convinced I need to spend the money.

sorry for the long post.

Delig · Jul 31, 2023

I replaced the starter switch and everything is good.

New one wire 12v conv on Farmall cub

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