140 farmall wiring

69fastback393 · Apr 11, 2009

i did complete rewire on my 140 farmall today everything came out great except its not charging.
i used the warning light method (#1815 bulb) instead of a diode.what i have found out is when i bypass the light by connecting the 2 light wires together it works.
can i jump a diode across the 2 light terminals and make it work?
has anyone ran into this before? where do i by these diodes?.....thanks

JMOR · Apr 11, 2009

Use a 10 ohm resistor, like GM did. :idea:

69fastback393 · Apr 11, 2009

where do i mount the resister? where can i buy them?

JMOR · Apr 11, 2009

Radio Shack, 10 ohm, 6 watts or greater, 2 for $1.99. I would probably stick it across the bulb socket terminals, but just pick a spot.

69fastback393 · Apr 11, 2009

thanks jmor i will give it a try. has anyone ran into this before?

JMOR · Apr 11, 2009

Yes, the problem is that the field 's full current is over 3 amps & your bulb may supply about 0.2 amps. It doesn't need to supply the full 3, but GM in all their wisdom? decided on about 1 amp, so you are way short, hence the 10 ohm resistor.

rvirgil_KS · Apr 11, 2009

Radio Shack Catalog #: 271-132

10 ohm 10 watt

Hugh MacKay · Apr 12, 2009

Fastback: You've answered your own question, run those two wires back to the dash, and connect in a push button switch. Everytime you start the tractor hit the push button and it will excite the alternator every time. You'll find you can't leave those two wires connected as it will drain the battery when tractor is not running.

Toss the light and diodes in the dumpster. I've had 2 offset tractors on alternator charging for 18 years now. The tractor that has been push button excite from beginning, has been trouble free all those 18 years. The second tractor I played around with lights, diodes, etc., was continuous trouble until 4 years ago, changed that one to push button. I bought a 140, 6 years ago, went with push button excite from beginning and it has been trouble free. Now, everytime I go to town, I don't have to be shopping for lights, diodes, resistors, etc.

I notice later in the thread you mention resistor. Heave that in the dumpster with the other junk, go buy yourself a good 12 volt coil. I use my tractors, trouble free is my game plan, fix em right and you don't have to be tinkering all the time.

69fastback393 · Apr 16, 2009

ok, i resoldered the wire back on my warning light and soldered a prt# 271-132 resistor from radio shack across the 2 light terminals and it still wont charge and light stays on .i then unsoldered the wires and connected them together and it charges again .
basically i have not had the problem of tractor continuing to run with it wired without a light,diode or resister.i just wanted the warning light to work being i have installed it.
will it drain the battery without either of these?

mkirsch · Apr 16, 2009

Yes, it will.

69fastback393 · Apr 16, 2009

it is wired by the diagram Step by Step 12-Volt Conversion
by Bob Melville

69fastback393 · Apr 16, 2009

why is this setup not working? what do i need to do?

TheDurk · Apr 16, 2009

Did you try Hugh's push-button setup? If it charges with direct wiring but not with resistor/diode/light the push-to-excite approach still ought to work.I am thinking slipping belt or too large a pulley on the alternator making it hard to excite. You never say exactly what alternator you have or what you took it, and its pulley, off of. Care to share??

69fastback393 · Apr 17, 2009

(quoted from post at 23:08:52 04/16/09)
Did you try Hugh's push-button setup? If it charges with direct wiring but not with resistor/diode/light the push-to-excite approach still ought to work.I am thinking slipping belt or too large a pulley on the alternator making it hard to excite. You never say exactly what alternator you have or what you took it, and its pulley, off of. Care to share??

what i have is a 10si alternator.i have a wire running from the acc on the switch to the light..out of the light to the #1 terminal on the alt...i have a 10ga wire running from the battery side of the solenoid to the amp guage then from the amp guage to the battery terminal on the alt with the #2 also connected to the battery lug on the alternator..i ran the coil wire to the ign terminal on the switch...i do not have a problem with it running with the switch off... i guess my biggest concern is why i have to have constant 12v to the #1 wire for it to charge when hughs push button setup works with only commentary contact.what ever the problem is i think might be why its not working through the warning light. could the regulator be causing this problem? maybe charging all the time.

69fastback393 · Apr 20, 2009

problem solved!
i thought i would take a shot in the dark and replace the regulator so after tearing down the alt. i decided to check the diode trio and it was bad so after no one having a diode in stock i went ahead and replaced the alt. and hooked up the warning light as i did in the beginning.i switchd the tractor on and the warning light came on, i them cranked the tractor and light when out and everything is good.
i just wanted to thank everyone that replied to my post and maybe i can help someone along the way.

140 farmall wiring

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