Start the car and disconnect the negative battery cable. If the car dies, the alternator is typically bad... but, to be on the safe side, take it to your local parts store, like Autozone. they test them for free, and will leave no mistake about it.
Check for a bad fusable link at alternator
How to Tell If Your Car Alternator Is Bad Check related link below…
Many possibilities. Check in theis order: Bad battery connections? Bad battery? Loose alternator belt? Bad alternator connections? Bad alternator? (Test at auto parts store.)
If it is noisy, loose, or hard to turn, it is bad.
The diode in the alternator is probley going bad, Check charging system. And replace alternator.
It could.
Check voltage with a voltmeter at the battery With engine running readings should be 13.8-14.2 With engine running hold a screw driver to the back of the alternator, if there is no magnetic field, the alternator is bad.
I have a 2.0 1995 Mercury mystique the battery charge light was on no output on old alternator. Replaced alternator No output from new alternator "charge light out" (wiggle test wires& re-check wires) at alternator *still no output* is there a fuse that could be the problem or just another bad alternator... I would check the alternator plug before getting another alternator, it may be bad. And is a lot cheaper to replace.
Unhook ur positive terminal on battery while car is running if car turns off while doing this u got a bad alternator
A bad belt, a bad regulator in the alternator or bad brushes in the alternator.
A bad battery will not turn on a check engine light. A bad alternator however will. Have your vehicle checked and see if the alternator is putting out at least 13.5 volts and if so there may be another issue causing the light .
If the car won't start, jump it off. While it is running, remove the positive cable from the battery. If the car dies, then your alternator is bad. If it keeps running then you may have a bad battery.