For some reason my alternator off my 92 TBI is not charging the battery. I have had the alternator tested as well as put in a new one, same problem.

I can hear it click on as well as watch my volt meter go to around 14v for a couple of seconds and then stops, and volts go back to 9-10. I used a tester light to test the only lead wire to the alternator, and it is getting juice.

What I dont know, is what tells the alternator to turn on? Is it the voltage in the lead wire?

So where is my problem? Is the alternator not being told to turn on correctly?
Thanks for the help.

Chris

Anyone have any ideas?

well if its a standard one wire alt, i belive they are internally reglated and maybe it took a crap, bt yo stated that you tried another alt and had it tested so there must be a short somewhere inbetween is my guess! jiMMy

The alernator has two wires, one exciter wire, and then the one charge wire. So does this mean that I am externally regulated? Like I said, it charges for just a few seconds, so is that a sign of my regulator being bad?

Thanks

they just call it a one wire alt, one wire goes to a post on the back and the other is probably a plug? still interanlly reglated i blieve. jiMMy

There should be 3-4 wires coming off the back of the alternator.

One wire is seperate and larger gauage that goes to the battery.

On the plug, one of the wires is red and another is tan with a white stripe.

The red one goes to the battery also(ie +12 all the time).

The tan with white stripe goes to a +12 hot in run source.

The third wire I've never dealt with but I've cut the wire out of a circuit with no problems.

If the alternator is checking out fine, I would check the wires at the plug. Very simple to do.

Get a test light and check that the red one is always lit up and the tan one is lit when the ignition switch is turned to run.

Originally posted by Lil'John
There should be 3-4 wires coming off the back of the alternator.

One wire is seperate and larger gauage that goes to the battery.

On the plug, one of the wires is red and another is tan with a white stripe.

The red one goes to the battery also(ie +12 all the time).

The tan with white stripe goes to a +12 hot in run source.

The third wire I've never dealt with but I've cut the wire out of a circuit with no problems.

If the alternator is checking out fine, I would check the wires at the plug. Very simple to do.

Get a test light and check that the red one is always lit up and the tan one is lit when the ignition switch is turned to run.

Lil'Jon:

There are only 2 total wire coming from the alt. The one that runs to the battery, then one other that is connected to the plug, a brown wire.

Chris

Lil'Jon:

There are only 2 total wire coming from the alt. The one that runs to the battery, then one other that is connected to the plug, a brown wire.

Chris

The wire that runs to a plug is switched by the ignition switch, and excites the alternator. The other (Big) wire is the charge wire. The alternator is internally regulated. Unless you have a blown fusible link, or another bad connection to the battery, it sure sounds like bad alternator. Check voltage on the big wire at the battery when you first start it....If it stays low, doesn't jump to 14 plus, your big wire is interupted, like blown fuse or fusible link. Good Luck!:D :D :D :D

Originally posted by 4Wheeldog
The wire that runs to a plug is switched by the ignition switch, and excites the alternator. The other (Big) wire is the charge wire. The alternator is internally regulated. Unless you have a blown fusible link, or another bad connection to the battery, it sure sounds like bad alternator. Check voltage on the big wire at the battery when you first start it....If it stays low, doesn't jump to 14 plus, your big wire is interupted, like blown fuse or fusible link. Good Luck!:D :D :D :D [/B]

So are you saying that the exciter wire is what turns the alternator on? Because I check current (with a test light) to the exciter wire and there is current, but the alternator is not kicking on. Now, internally regulated means that it checks that exciter wire for low voltage, and when it is low kicks the alternator on? Because like I said, the exciter wire always has current, but the alternator only comes on for a couple of seconds.

However, I put a brand new alternator in, and it also does not kick on.

Chris

i told my brother to use a jumper wire from the batt, to the back of the alt. where the switched 12 vol source goes. and to see if that'll kick he alt on. and i think if it kickes it on, then that means there is a problem with the 12 volt switched wire from the ignition. then if it still doesnt work, then i would try using a test light or a volt meter, to see what the large red wire coming out of the alternator, going to the battery puts out.
pat
sound right???