Farm Equipment - D-15 electrical mystery?

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D-15 electrical mystery?

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Category: Allis Chalmers
Forum Name: Farm Equipment
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=37205
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Topic: D-15 electrical mystery?

Posted By: JERRYH
Subject: D-15 electrical mystery?
Date Posted: 13 Sep 2011 at 12:08pm

I have used this tractor for about ten years with few problems. The battery was setup as a negative ground. Now when I hookup the negative (after having first connected the posivtive) I am getting sparks on the negative battery post (this is without the key in the ignition). My thinking is that my ignition switch is faulty. Any help would be welcomed.

Replies:

Posted By: Butch(OH)
Date Posted: 13 Sep 2011 at 12:17pm

Pretty simple wiring on those but the possibilities are many. Been converted to an alternator? Could then be a bad diode. Unhook the wire at the alterantor going to the battery and check for spark again at the post. If still a generator the cutout relay in the regulator could be stuck, Same deal, unhook the wire from the "Batt" terminal and check at battery again. Or loosen the belt driving the generator and if it trys to motor when you connect the battery your regulator is bad. From there you need a meter or test light, voltage should be going into both the ignition and light switches but that's it, as I remember the power for the light swith is jumpered over from the ignition switch. You also need to check all the wires and cables that are hot when ever the battery is hooked up to see if they are rubbed bare and grounded. Good luck. If the battery has been backwards, even if just touched you will likely need to re-polorize the generator or you will be chasing all kinds of wierd problems and buying more hi-buck regulators.

Posted By: Gerald J.
Date Posted: 13 Sep 2011 at 12:27pm

Can be any of many things.

Can be a stuck cutout on the generator.

Can be a bad diode or two in an alternator.

Can be an abraded wire.

Can be a light switch on.

Can be an ignition switch on.

Can be a failing starter solenoid.

Can be a radio left on.

Can be a capacitor charging in a radio noise filter circuit.

There's no way to tell from a spark at the battery post.

The standard way of searching for such a problem is to connect a 12 volt test lamp between the battery post and the battery cable. Then you take the wiring apart (preferably logically) until you find the circuit (and it won't necessarily be just one circuit) that turns the light out when disconnected. You can use a test lamp to check for voltage on the load side of switches that should be open, like lights, ignition, and the generator side of the cutout.

Take notes and maybe pictures before you take things apart so you can put them back the same place they were.

Gerald J.

Posted By: cmsmoke
Date Posted: 13 Sep 2011 at 2:20pm

Jerry, Is it the same battery that you took out of it 10 years ago?

Posted By: JERRYH
Date Posted: 13 Sep 2011 at 3:15pm

During the past ten years I have probably bought 3 or four batteries and installed them as "negative ground." One time I tried to jump the tractor with my Astro Van. I connected the cables as usual, but when I connected the final cable (to the neg terminal of the tractor battery), I got a big shock. I never attempted it again.