1440 Combine Alternator

Recently I changed the thermostat on my 1440 combine and had to remove the alternator to do so. After I reassembled everything and the thermostat worked fine and the alternator is charging, I am now having problems with the (new) batteries going near dead overnight. I happened to notice this morning that the alternator is warm (not hot) to the touch. My question is, have I hooked the small wires up incorrectly? There are 3 wires coming out of the harness although for as long as I have owned the combine, only 2 of them were ever connected to the alternator although there are 3 terminals on the alternator. One of the small wires going into the alternator is constantly live and even with the key off produces a small spark when connected. Please note that I am not refering to the larger battery wire coming out of the alternator, but the lighter ones that are usually in a plug. The plastic plug is long gone and now the wires are indivdual. I believe it is a Delco alternator. Thanks in advance for the help.......Rich.

You should take some pictures of that alternator showing the wires and post them. For now I would disconnect the battery ground cable so the battery isn't drained. Hal

If it is a Delcotron with an external VR, the wiring is shown below. For now, remove the sparking connection. If it is a 10SI Alt, with edge mounted small terminals, the # 2 terminal should be hot all the time, and the #1 terminal should go to the idiot light. Jim

" One of the small wires going into the alternator is constantly live and even with the key off produces a small spark when connected. Please note that I am not refering to the larger battery wire coming out of the alternator, but the lighter ones that are usually in a plug. The plastic plug is long gone and now the wires are indivdual. I believe it is a Delco alternator. Thanks in advance for the help.......Rich."


That combine came with a Delco 10SI alternator originally.
You state the plug is long gone and the always hot wire makes a small spark when connected.

looking at the rear of the alternator case where the small wires plug in, you will see the case marked #1 on the left, #2 on the right. The wire that is hot all the time goes on the right hand # 2 terminal and the other which is hot only when the ignition switch is on, goes to the left #1 terminal.

I would say you have those wires switched which keeps the alternator field active all the time. This puts a constant 3 amp drain on the battery. causing the dead battery and warm alternator.

Please go to your local auto parts store and get a Delco alternator harness repair plug.(80 chevy) You will get a new plug with short pigtail wires and crimp splices to attach it.(about $3)
This will keep the wires installed correctly and prevent a very real electrical fire danger. Without that plastic plug, the # 2 sense wire, which is always hot with full battery power and unfused, need only be bent about 1/8 inch to short to the alternator case and almost instantly burn up that # 2 wire.

Thanks to everyone for your help. I did indeed have the two wires hooked backward. I guess a 3 dollar plastic plug is a small price to pay to prevent a combine/barn fire. Thanks again...Rich