Alternator working correctly?

[whitedragond1]

I'm wondering what the best ways to tell if an Alternator is beginning to die. When I hooked up the battery charger/alt tester, it would be around 90, then 95, then 89, then it would drop to 70%, then back up. When I turn on my headlights idling in neutral, the dash battery gauge needle will hold, then drop, then hold again.

Is this a symptom?

Could it be a problem relating to a voltage regulator of some sort?

Could a bad alternator cause the MAF voltage to be low?

Grounding connections?

Any help is appreciated.

Thanks!

[Rob Bell]

Re: Alternator working correctly?

At idle the vehicle's system voltage should be about 14V give a take a few tenths. Usually it's like 14.25 - 14.5V If it's moving around or too low or too high, the alternator and charging circuit needs to be checked. You should check the ground cable from the battery, the positive cable from the battery, and the positive cable coming from the alternator. I believe the voltage regulator is internal, and I'd guess that most alternator problems come from the voltage regulator. It's probably the weak link in the system.

I don't think a bad alternator would cause the MAF voltage to be low, as long as your system voltage does not drop below 12V.

The two main things to check are the battery and the alternator. Is your battery over 5 years old or have more than 50K miles on it? Then it needs to be replaced... even if it seems good. Same thing if it has ever been run totally dead. Once a battery has been totally run down, it is never the same. Replace it before winter comes, because it will choose the crappiest day/place/time to die on you.

If the battery is good and your voltage is fluctuating and dropping out and coming back, I'd suspect the alternator. If the connections check out nice and clean, get it tested and probably replaced.