Battery light on?

check the fuses and fusible link in picture any of them will effect whether your car charges or not. also recommended replacement of belt and tensioner is 60,000 miles which most of time if bad will not charge at idle or low rpm's. This guide can help us test the alternator

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Check out the diagrams (Below). Please let us know what you find.

After starting my car, a few minutes later the battery light comes on. The lights don't dim when I'm driving it so I don't think it's the alternator, and everything works fine when I'm driving it as well. I tried cleaning some of the corrosion off (there wasn't very much but I cleaned it anyway) and tightened the bolts to the positive and negative cables, but that didn't fix the problem.

How old is the battery?

Time to get out the trusty multimeter and check battery and alternator output voltage.

The battery is the same one from when I bought the car about a month ago. It looks fairly new, but the guy could have just cleaned it up. I tried looking for a date or any indication of how old it was on the battery itself. Do you know of any way to see how old it is without a voltmeter? I don't have one.

Look for the date code on the side. Alphanumeric.
You can pick up a decent meter at places like Autozone for about 20 bucks. You could also take the car to one of those places and have them do electrical tests, usually for free.

Just checked. The battery is 5 years old, I'm not sure how long car batteries are supposed to last but I'm assuming that's pretty old. I'll run by autozone and have them check it just in case before I buy a new one. Thanks for your help!

My pleasure. Most car batteries last anywhere from 3-5 years. I should rephrase that: Most car batteries have warranties that last 3-5 years.

Battery light goes off and on. Off when I unplug the two wires to the alternator and, on when I plug it back in. I tested both sides of the wires in the harness and get 12.67 volts. I checked wire back to fuse like to fuse box and looks okay. Did not slice open fusible hoping it is okay.

Hey Joe,

Looks like you need an alternator but to be sure lets follow these guides to replace the alternator and check the wiring.

https://www.2carpros.com/articles/how-to-replace-an-alternator

and

https://www.2carpros.com/articles/how-to-check-wiring

Please run down this guide and report back.

Cheers, Ken

My alternator and battery tests good. What could be the cause for my battery light to flicker during hard acceleration?

Georgiadawgs2015
August 12, 2015.

My 02 mustang gt does not have female spade connector on the alternator. Still trying to find out why my battery light is flickering on and off.

Georgiadawgs2015
August 14, 2015.


My battery and alternator was tested at auto zone.

Georgiadawgs2015
August 17, 2015.

I changed the alternator again. So for battery light not coming on. I've heard mustangs are bad on alternators?

just in last couple of days, the battery light goes on now and then.stays on at times 1-2 mins. or less thank 15 secs. Today it never came on. Can't seem to fix on weather having a/c on effects it. I'm original owner and never had this. battery is 2006. living in Phoenix heat never had this effect.

Well I would take it to a local parts store that will do a free charging system test and have them test the system. It may be that the alternator is bad. Also check the battery cable connections for any corrosion is there is corrosion then clean the cables. Let me know what you find. Just for fun any performance mods?

[quote:6e3ecbe3c4="racefan966"]Well I would take it to a local parts store that will do a free charging system test and have them test the system. It may be that the alternator is bad. Also check the battery cable connections for any corrosion is there is corrosion then clean the cables. Let me know what you find. Just for fun any performance mods?[/quote:6e3ecbe3c4]

I read a shortcut. Instead of taking it to a parts store etc...Start the car and then take the " ground " cable off . If the engine dies immediately then the alternator is the problem. Any truth to this ???
Thanks Mike.

NO please do not do that. This is only a good test on generators not alternators. This will spike the alternator and could ruen it and maybe even spike the computer and take it out too. SO please NO don't do it just go to the local parts store and have it tested they usually do this for free so the only cost is the gas. Let me know what you find with the test.

Hello, I have a 1995 mustang gt that's not charging. I've checked the fuses, replaced the alternator and still nothing. I also don't get the alt light in dash when I turn key on, if my model year has one?

That missing light is a big clue as that provides the turn-on signal. Measure the voltage on the green / red wire in the plug on the back of the generator and holler back.

I have a 2000 mustang. It has a V6 3.8 liter engine. It has 128,000 miles on it. The indicator light with a battery on it came on and im not sure whats wrong. I cleaned the posts of corrosion but light still on. i took it to auto zone and had the battery checked and the man said i need to charge the battery. My question is why would i need to charge the battery?the car is running and starting fine-and how do u charge the battery?

2 possibilities here, 1 the Battery has reached the end of it's useful, and dated life, ie. 4 year battery is 4 years old. 2 the alternator is not charging your battery, Did they check your charging system, or just the battery? If the car runs go have the charging system test at Autozone, they test for free.

Take off the negative cable with the engine runnin if it dies the alt. is no good