The ammeter reading in the red does not necessarily mean an electrical short. It only means that the tractor is consuming more current than the alternator is producing, and the battery is making up the difference. The ammeter measures current flow in/out of the battery.
The factory alternator has 3 connections. An output terminal with a heavy wire that has a path to the battery through the ammeter, and 2 smaller ones that connect to the voltage regulator.
The 2 smaller wires are marked "F" and "-". The "-" is simply a ground wire. The "F" terminal connects to the alternator field winding. When a voltage is applied to this terminal current flows through the field winding, causing the alternator to send current out of the output terminal.
If you do not see a half a volt or so increase the the voltage on the output terminal when the engine starts, The next step is to check for a voltage on the "F" terminal. If there is a voltage present, the problem is the alternator.
If there isn't any voltage on the "F" terminal, the next step would be to find the voltage regulator.
The voltage regulator will have 3 connections to it, a ground, a wire that connects to the alternator "F" terminal, and a wire that connects to switched 12V.
Check for voltage on the wire going to the alternator. If voltage is present you have an open connection between voltage regulator and alternator.
If no voltage was present check for voltage on the terminal that goes to the switched 12V . If voltage is present here you have a bad voltage regulator. If no voltage is present trace this wire back. It probably goes to the fuse box. On my tractor it is connected through a 3 Amp fuse, the wiring diagram posted previously does no show this fuse, so your tractor might not have one.
As others have mentioned, if either the alternator, or regulator are bad, the cheapest solution would be to replace with a GM internal regulated alternator.
Stan
The factory alternator has 3 connections. An output terminal with a heavy wire that has a path to the battery through the ammeter, and 2 smaller ones that connect to the voltage regulator.
The 2 smaller wires are marked "F" and "-". The "-" is simply a ground wire. The "F" terminal connects to the alternator field winding. When a voltage is applied to this terminal current flows through the field winding, causing the alternator to send current out of the output terminal.
If you do not see a half a volt or so increase the the voltage on the output terminal when the engine starts, The next step is to check for a voltage on the "F" terminal. If there is a voltage present, the problem is the alternator.
If there isn't any voltage on the "F" terminal, the next step would be to find the voltage regulator.
The voltage regulator will have 3 connections to it, a ground, a wire that connects to the alternator "F" terminal, and a wire that connects to switched 12V.
Check for voltage on the wire going to the alternator. If voltage is present you have an open connection between voltage regulator and alternator.
If no voltage was present check for voltage on the terminal that goes to the switched 12V . If voltage is present here you have a bad voltage regulator. If no voltage is present trace this wire back. It probably goes to the fuse box. On my tractor it is connected through a 3 Amp fuse, the wiring diagram posted previously does no show this fuse, so your tractor might not have one.
As others have mentioned, if either the alternator, or regulator are bad, the cheapest solution would be to replace with a GM internal regulated alternator.
Stan
