Farmall 140 converting to alternator

cdd

Member
I wired this up as this picture below shows. Charges good but when I shut the tractor off the warning light comes on and stays on until I disconnect the negative terminal on the battery. Any ideas? Am thinking that I might be getting a short between term 1 and 2 on the alternator.
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Are you sure you have the lamp connected to the switched side and not battery side of the ignition switch?

If switch wiring is correct and alternator is shorted 1 to 2, the lamp would be powered from alternator and ground through coil and distributor. If so roll the engine over with switch off and lamp should blink as points open and close.
 
Yes it is on the switch side. I will see what happens when I turn it over with the switch off
 
Looks like to me when you shut the tractor off you still have power to your alternator and light which will run your battery down. I would run the wire from the solenoid through you off/on switch then to the amp meter so you will shut all power off when switch is off.
 
Very simple you have the #1 wire which is the one with the light in line on the wrong side of the ignition switch. When I convert many of the tractor I have done I just hook the excite wire to the ignition side of the coil so as to save wire and make it easy to be sure I have it wired to the correct side of the ignition switch
 
"I would run the wire from the solenoid through you off/on switch then to the amp meter so you will shut all power off when switch is off."

I disagree. The way the diagram shows the charge wire from alternator, through ammeter, to large battery connection at the starter activating switch, and then the supply for switched operating power coming off the alternator/generator side of the ammeter was the way nearly all tractors/vehicles were designed.

The cut-out relay on the generator or in the generator regulator would open the current path when generator is not charging. The polarity of diodes in the alternator would prevent reverse current flow when alternator is not running.

Many of the stock ignition switches would not handle the battery charging current.
 
I always use an alternator harness repair plug from the auto parts store(about $3) that look professional are safe from shorting a terminal to the alt case and causing an electrical fire and make it impossible to get the #1 and #2 wires reversed or shorted together. Another possible reason for the light coming on when the ignition switch is off is the alt light feed wire connected to the ign switches BAT terminal instead of the IGN terminal.
 
It is wired correct if wired as shown in the diagram. There is a problem with feedback to your #1
terminal from a bad diode or the internal regulator has a problem. Is the alternator a used, rebuilt
or new unit? You are using a Delco 10si as shown? I not sure of the correct wiring for other
brands of alternators.
 
Thanks for all the responses.
It is a new Delco 10SI - had it bench tested prior to purchase and it is producing around 17 v when running.
I do need to get an alternator repair plug. I looked at them and everything is taped up, doesn't look like a short.


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(quoted from post at 07:06:57 10/27/17) Are you sure you have the lamp connected to the switched side and not battery side of the ignition switch?

If switch wiring is correct and alternator is shorted 1 to 2, the lamp would be powered from alternator and ground through coil and distributor. If so roll the engine over with switch off and lamp should blink as points open and close.

It does blink with switch off when I turn it over,. So I have a short at the terminals?
 

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