Electrical problems

[ryansm1]

I wound up buying a new alternator (not sure if I needed it or not, but now I'm stuck with the new one). It's supposedly good, but I'm still having problems getting the car to stay running.

I had a blown fuse in-line from the terminal on the driver's side fuse box from the battery to somewhere, which has been replaced, but I still am getting no current from the alternator. I have a connection between the alternator's post and the post on the fuse box (and the battery terminal), but I am getting maybe 1.2v on the line when the engine is running.

I checked the ground from the battery; it is fine. All the contacts for the battery are clean. All the fuses in all the fuse boxes check out. I don't know if/where any in-line fuses between the alternator and the battery exist, but I have a connection between them.

I can't for the life of me find why the alternator refuses to charge the battery; I had a guy at Autozone test it, claiming it showed a little over 12 volts when turning, so it is supposed to be good, but I can't get any kind of current off of it. Even while testing the terminal on the alternator, I can get maybe half a volt at idle. I am still thinking it is bad; is there any way I can test it myself (other than what I've already tried)?

Am I just getting the run-around with the alternator because the guys at Autozone don't want to take it back, or is there something else wrong?

The neighbors are getting irritated with my strings of profanity after every failed attempt, so if anyone can help, I would greatly appreciate it.

[sharkey]

RE: Electrical problems

is it a 1 wire alternator or does it have the main wire and a white plug??? if it has the white plug, check to see if one of the wires has 12 volts to it. in order for it to charge, it needs to be "exited" with power. if there is no power there, then it wont charge.

[ryansm1]

There is a heavy gauge wire coming off the alternator, but there is also a black plug that goes into the plastic part of the housing that has two pins (in a four pin plug). Is that what you are referring to?

Thanks for your help.

[3100 MPFI]

IT helps to know the year of the car, and the engine.

For the main big wire, it should go from the post on the alt, to the STARTER, and from the starter to the battery.

I would do a continuity test (from alt to starter, and from starter to batt) to make sure that there is not an inline FUSIBLE ELEMENT that has fried and broken.

Going by a 1993 3.1, the Other two wires are both BROWN. one that goes to the IGN fuse at the right side electrical senter (you should be getting 12 volts at that wire when the key is ON). That is the wire in location "F" in the plug (the letters shoul be on it real small).

Wire "L" goes to the CHECK GUAGES light (to the cluster).

According to my book, the "F" wire has to have POWER when the key is on.

There is also a Fuseible element between the starter and the alternator. I would check that out. If that all checks out, then there is most likely a problem with your alt (and bad ones do happen).

Let me know whay you cars year is, and which engine it is, and I will look into it further.

[ryansm1]

Sorry, it's a 95 Grand Prix, 3100.

I've been able to get continuity between the alternator and the battery, so I wouldn't think there would be any blown fuses between the alternator and starter or starter and battery. I'll check again, though. Thanks

[geoffinbc]

Check that exciter current. It needs to be there. It sounds like that is what is missing.

[ryansm1]

I found one of the inline fuses that fried, and now need to replace it. I don't understand why I was able to get continuity, but it's broken.

Everything else seems to be fine, so hopefully that is all that is wrong.

I guess this should have been obvious, but thanks for all the help!

[the4biddendonut]

you may have gotten continuity because you didn't isolate the wires you were checking well enough from the rest of the car.

here's a simple example. you have a bulb hooked up to a battery, and there's a break in the wire, so you know there's a open circuit. if you hook up your continuity tester leads up to each end where the break in the wire is, you will get continuity.

the reason is because the current will run from the break in the wire, to the bulb, through the other unbroken wire, through the battery, and back the break in the wire again.

so, there may be more that one path is what i'm trying to say.

hope that helps.

[Juglenaut]

I agree.

The only real way to test for continuity is by using a amp meter, clip on style, when testing hot leads in reference to ground, a regular VOM will not test right in a ground loop system.