I just got my "Brake Light" and "Battery Light" on recently when I start up my car, but whenever I let it warm up a little/step on the gas a little... the lights will gone together...

So, I bought it to the dealer, and they told me that the alternator only has around 11v... :confused:

And they told me I have to replace the alternator ASAP... and IT COST $350

So, I check pepboys or autozones, their parts is like < $100

And my question is, DO I NEED TO REPLACE THE ALTERNATOR NOW? if so, how hard to do it by myself?

Thanks

the alternator can be done by yourself if you have some car experience...there are threads on it here...just do a search for alternator installation

It's a fairly easy DIY, the most important thing is to disconnect the battery first.
And yes you should replace it ASAP, your car is now running on just the battery and once it goes dead it won't be running at all. Chances are the battery is shot now as well and should be replaced at the same time.
Be careful what you get at a parts store, their "rebuilt" alternators may contain a lot of reused parts.

the reason why i am thinking should i replace the alternator ASAP is that the car is running normal, it just that the break light and the battery light is on when the car start (sometimes) Is it really that serious so that i have to replace it right away?

The car is not running "normal", it is running off the battery most or all of the time without the alternator to properly recharge it. So, depending on how fully charged the battery was to begin with, and whether the alternator is now charging at all, you can expect a dead battery at some time in the very near future.

I just checked the alternator again at AdvanceAutoParts before I get one from them, those people told me my Alternator is good...

So, if the alternator really go bad, is those lights (Break Light and Battery Light) will stay on? or just turns on for a couple of second and then turn themselve off?

Please help... I am so confuse now

Thanks

We can go back and forth about this for days. There is something wrong if those lights are coming on at all, it should never happen. You should never see the battery light except when you turn the key to "run" before starting the car, once the engine is running it should stay off.
You've had a dealer tell you the alternator is NG, that plus the symptom of the lights is all the reason you need to replace it. Get a second opinion from an independent shop if you want to, but IMO you're just wasting time here.

Checking the alternator is easy if it's still on the car. Measure the voltage across your battery terminals with and without the car running. If the voltage doesn't increase to at least 14V when the car's running, then your alternator is gone. If your battery reads less than 12V with the engine off, your battery needs replacing. You obviously have some type of electrical problem since your warning lights are on.

Be careful what you get at a parts store, their "rebuilt" alternators may contain a lot of reused parts.


most parts store places (napa, checkers, autozone...) give you life time replacement on alternators... I went through 5 of them on my old ford tempo before they realized they had given me the one for the AWD tempo, which is designed to spin slower... I was spinnning it to death at a higher speed. anyway, this was at NAPA, they had no problems exchanging it, i didn't even need the receipt, they just pulled it up in the database.

CharT

Just because your battery is under 12v with key off does not neccesarily mean the battery needs to be replaced. You need to load test the battery to be sure, it could just need a recharge. This does not sound like a battery issue at all

i just check the battery, before and at running...

Before start, my battery has more than 12v, but right after start (only happened randomly), the battery just show a little more than before start, and the "Battery light" and "break light" will stay on... but when I step on the gas to rev up alittle, then those light will go off, and the battery will read as more then 14v... and will stay at above 14v, even if I turn on most of the accessory....

Replace your alternator!

I am going to do it, just that i want to know why and understand more about it, please stop acting so rude

Not being rude, just going in circles here. Your original question has been answered multiple times, if your alternator is not charging at idle and the battery light only goes out when you rev the engine, the alternator is bad and you have to change it. Nothing more to be said at this point.