Thread: WTF is my alternator bad?

On the way home from the store tonight, my car was acting weird. My dash lights were dim and the radio was cutting off and back on a few times. Then my abs light came on, then the airbag light started flashing, then the brake light came on as well. Funny thing is everything returned to normal as soon as I got to my driveway. Dash lights were back to being bright like normal and the warning lights turned off too. So what is this? Is it the alt? I only drive my car maybe twice a month, short trips too. Maybe my battery is not having enough time to charge up? Battery is pretty old (3 or 4 years old) and the alt was changed last October.

I'm hoping it's the battery. Did some searching and found that a failing battery can f up my alternator.
http://answers.yahoo.com/question/index?qid=20070704095755AAWCmQE

Pull your altenator and take it to have it tested

first test that battery, cause by the way your driving that car and the age of the battery. i'd say its stuffed batteries only last about 3 years and don't like been left for long periods and they like to be charge on longer trips like 20-30min stints

if your not using for long periods you might wanna look at getting a maintance charger they don't cost much

Thanks guys for responding. I do have a charger like that too and I also have a digital multimeter. How do I use this multimeter to test the battery? I was trying to use it to check the voltage of the battery, and the test leads were sparking. What setting should the multimeter be at? Yes I fail at car stuff.

Multimeter at Voltage DC, black to neg red to pos . I hope it's auto-ranging for your sake.

Be sure to measure voltage on the batery not under load and under load. The difference in output shouldn't be too high It should measure over 12Volt no load, with engine and alternator running 13,8Volt and at cranking it shouldn't drop to 10Volt for example

Make sure you measure DC in the 0-20 range

when you test the battery if it drops too low its no good. To see the drop your going to have to put a load on it for instance headlight, defrost etc. If you get 12.0v-12.6v no load and nothing lower then, i believe its 9.6v with load, your battery is good.

flashing dash lights are normally a sign of bad alt that what happened to me, or a short or bad ground to the alt.

I tested the battery last night. It read 11.9, but I didn't test it under load, it was too late in the night for that. If it does turn out to be the alt how much do they go for? I remember those being really expensive on my Z.