Originally Posted by RiftRover
The idiot light does not come on with the engine off and the ignition on. What does that mean?
The field wire is the small exciter wire.
This is suppose to be hooked to one side of the ignition warning light (that John asked about).
The other side of the ignition warning light is connected to positive that is switched on and off when the ignition switch is in the run or off position.
When the key is on the light will glow because the ignition side of the light bulb has power from the ignition switch and electrons flow through the bulb filament to the alternator field.
When the engine is started, the light bulb stops glowing because the alternator is producing (+) current and the electrons stop flowing (mostly) because the current is balanced on each side of the ignition warning light bulb.
If ant part of this circuit were grounded, it will short out the voltage regulator inside the alternator (again that John asks about).
Sometimes, but not always depending on where the short is, the light bulb filament can act like a fuse and protect the DC regulator by burning the warning light bulb filament out.
You need to do 3 things Mike:
1.) Follow John's advice and discontinue driving the vehicle as long as you are overcharging the battery, which will ruin it.
2.) Have the alternator checked and if defective (sure sounds like it) fixed or return it for warranty... (if it came from me you get 12 months).
3.) Inspect and fix your wiring because if your wiring is faulty, the next alternator you install will suffer the same fate as the one you have NOW.