I must be overlooking something and or have a lack of understanding of electric current. Anyhow I just re wired a Moline tractor that I got to running. I found an easy to understand diagram for an alternator and all seems to work great. All new wires and brand new volt meter. It has the on off swich then the push button for the starter. At first all worked great, Now the thing will not shut off with the switch. Now this is where it gets really strange. I have the switch going to the coil and then other wire going to the volt meter on the same post that the coil wire is on I think that is also the post that the sensor wire is hooked to I forgot. Anyhow when I turn the switch one direction the test light comes on when hooked to the posts ont he switch and the volt meter goes off. THEN when the light is turned off with the switch the volt meters comes on.... Also the switch now seems to be backwards from what used to be on and off. This is so strange it is almost scarey. I am not real good with electrics so maybe I am not understanding something???
- Thread starter R Wyler
- Start date
BushogPapa
Well-known Member
I have no real experience with your particular system but, I bet the Alternator is Back-Feeding the ignition system and needs a Diode installed, to prevent that..
My WD-45 has an alternator on it (and I need to put that diode on it) and it will shut-down ok, if the throttle is at LOW idle..any higher and it will kick back and act bad..!
The Diode that was recommended for me to use is a RadioShack #IN5408
3 Amp 100 PIV Diode..
White Band toward Alternator or #1 Terminal (to Ignition Switch)..
Another note I have has a radioShack part number: 276-1661
Hope this helps you...
Good luck..!
Ron.
Bob M
Well-known Member
Sounds like the alternator's backfeeding the coil after the ignition switch is turned off and while the engine's still spinning.
A fix is simple: Insert a lamp, resistor or diode in the wire between the alternator #1 terminal and the switched side of the ignition switch.
Lamp should be a 12 volt instrument panel/side marker bulb (#1815, #168, #194, etc). Resistor can be any resistance between about 10 and 40 ohms and rated for at least 1 watt. Diode should be a 1N1004 or similar. Wire the diode so the banded end connects to the alternator #1 terminal.
My personal preference is for a light. It will work as an "idiot light" for the charging system, same as on a car.
A fix is simple: Insert a lamp, resistor or diode in the wire between the alternator #1 terminal and the switched side of the ignition switch.
Lamp should be a 12 volt instrument panel/side marker bulb (#1815, #168, #194, etc). Resistor can be any resistance between about 10 and 40 ohms and rated for at least 1 watt. Diode should be a 1N1004 or similar. Wire the diode so the banded end connects to the alternator #1 terminal.
My personal preference is for a light. It will work as an "idiot light" for the charging system, same as on a car.
I agree with all the rest on the diode. Its a little more spendy, but my local auto parts house has wire unit that has the alternator plug on it and the diode already wired to it and an inline crimp for your wire to the switch. I usually run mine to the positive side of the coil. Very easy to do.
Irv
Irv
Thanks for the help guys. I will hook up the new reisistor I bought for it. The coil I bought new also has an internal resistor and it the paper said not to install it in a system with an external resistor. The diagram called for a diode and the parts store did not have one. The tractor G705 had a gen orginally but the alternator was on it when I bought it. The wireing was all mixed up so I went back with all new everything.
heiferduster
New User
If you wire in an alternator such as a GM 10SI, you can also get by without using an inline diode by simply ordering a switch from Napa (or a parts store) that has a additional ACCESSORY terminal on it. Run your ignition terminal to the coil and the alternator to the accessory terminal. In this switch you will not get feedback from the alternator because it "breaks" the circuit after shutting the switch off. I have used these in the past with good results. Hope this helps you.
Thanks for all the response. I put a diode in and it does shut down with the key now. But still when shut the tractor down the test light shows that I have juice going to the coil. Then when I turn it the other direction and the light goes out the volt meter comes on. This is when the engine is not running. Odd
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