How would you know if your alternator was going out, what would be the signs ?

Nicole; check the alternator belt, loose,worn, is it still there and on.
If battery is new and connections are good, and belt is good, probably a bad alternator. Alternator cost $125 to $200, labor $60-$120
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It means it's not charging , could have a bad fuse ! Check voltage at the large wire on the back of Alternator , should read battery voltage. Two fusible link's supply power , well it will read battery voltage if not open . if open fusible link is burnt .This is the charge line from alternator to the battery. An there is a three wire connector plugged into the alternator. One has Battery voltage an the other two go to the PCM - powertrain control module . for control ! Do you know how to use a volt meter ! Diagnosing Alternator Problems EricTheCarGuy

batt light, could be a sign of a malfunctioning alternator....check the alternator first and let me know

battery go dead

If you are constantly having your battery go dead frequently I would first check your battery, first to see if both the positive and negative cables are tight and making a good connection (if they are loose your battery will not charge properly) also look for signs of corrosion on the battery posts as well and check the batteries in service date which should be a sticker with a month and a year punched out. Batteries are mainly rated to last between 3-8 years. The garage should have a tester to allow them to check the output of the alternator while the vehicle is running. I'd ask them to show you that. Also lets say for instance you have a 60 amp alternator, at idle your alternator would produce less of a charge as opposed to driving down the freeway at 65 mph so if they show you that have them idle the engine rpms up and you should see an increase if not then you may have a worn out alternator. Some alternators can cost a lot so I would ask about a rebuild (if applicable) on your existing one to possibly save some money. Just be sure whatever you decide to find out what kind of warranty is included.

Take a close look at alternator as well. Low /dim headlights may be a sign of battery not receiving a charge from alternator. If bearings are gone in alternator, it will get noisy as well.

usually the alternator. Was the light on when the engine was running? If you jump start the car, does it die as soon as you take the cables off? These are signs of a bad alternator. If you have more questions or need instructions, please let me know.

going off and on randomly either indicates there is a bad connection in the charging system somewhere or that the brushes inside the alternator are worn and are not always making contact.
It could also mean that any other internal alternator component is beginning to fail...either way, unless you know how to rebuild one it means that it needs replacement.
Before replacing anything though, check all connections and also belt tension. You can have a test done at most larger parts stores that includes a battery and charging rate analysis. (most do that free).

Alternator may have failed. If you have a voltmeter, check voltage at battery with engine running. Should be at least 14 volts. If you don't have a voltmeter, you can take the alternator off and have the parts store test it. Let me know if you have more questions.

i don't know about the temp gauge,but i have a 2000 montero sport,and when my brake light and battery light came on,my alternator was going out.another sign for the alternator is the radio going off every once in a while,and then coming back on.