is the power supply wire to the alternator(not the one that sends charge to the battery, the other red in the multi pin connector) supposed to be hot all the time or only when the ignition switch is on? is this wire wired through the ignition switch? i have a short that drains batteries overnight and have eliminated most possiblities, the wire i asked about is hot all time and i'm not sure it should be. with the ignition off and key out the wire is hot and if you put your ear to the alternator you can hear a faint electrical "humm". also just had to replace the alternator for the third time, is this whats burning my alternators up and draining my battery? if this wire is only supposed to be hot in the ignition "run" position is the ignition switch the culprit or are there other possible things i need to check?


any help or advice is appreciated.

 

Well i am not shure of the colors but you should have a feed wire that is only hot when the key is on. and there should be another wire that reads what the voltage is on the battery to tell the alt how much to put out. The other wire should be hot all the time. Look in a Haynes manual to find the colors of the wires.

 

Yes that is probably your culprit of a dead battery. Make sure the key's off and pop your hood and listen to your alternator. If it kind of makes a hum like an electrical substation, your switch isnt shutting off power the the alternator like it should. My brothers firebird had that problem and it turned out to be a penny lodged in the fuse block just right. If thats the case check there i guess and go from there. Ignition switch maybe?

 

I tested the wires in the connector and the wire(tan/white stripe) going to connection "F" is hot all the time with the ignition off or on, I think it is only supposed to be hot in the "run" position on the switch. the other small brown wire is only hot in the run posistion. i know the "F" wire is supposed to have something to do with the factory fan wiring. this car is a carb conversion and most things related to the ECM are gone. the fan is run by aftermarket thermostat and relay straight off the battery.


Any ideas why this wire is hot and will disconnecting it affect my alternator performance at all?

 

well even with the "fan" fuse removed from the fuse box this wire is hot all the time. I thought this wire energized the field windings in the alternator because its connector is labeled "F". anyway as an experiment I disconnected this wire from the alternator, started the engine and checked the alternator. it still charges(14.4 volts) even without this wire. i haven't been able to track down were this wire is getting current from and since it doesn't appear to effect alternator performance i am leaving it disconnected. this was appearantly my battery drain because its been disconnected since saturday and no dead battery yet?

any thoughts or ideas about this, will this wire disconnected effect alternator life span?