Battery Light Woes

[ackuric]

So while driving my 99 mustang lately, once up to operating temperature my battery light comes on for about 10-20 seconds, and then goes back off on its own. Has done this during acceleration and during cruise, also today it came on twice, going off both times in 10-20 seconds. Both the battery and alternator have checked out good in testing done by checkers. No changes have been made in the electrical system. My mechanic and I are both stumped. Are you?

 

[BlownFiveLiter]

My guess, possible bad diode in the alternator, the voltage regulator is getting ready to go, or a bad connection somewhere. Most bench tests only check to make sure the output is within normal limits (12-16v), but if it's allowing the voltage to go above or below the normal limits, it will trigger the light.

 

[ackuric]

Where is the voltage regulator located? That was my next guess but don't know where its located or how to go about testing it.

 

[BlownFiveLiter]

It's internal, so if it fails, the entire alternator needs to be replaced.

 

[Stark77]

Mine does this as well. It has done so ever since i installed a tune via handheld. Car has perfectly fine voltage, light just comes and goes.

 

[TropicMustang]

I had the same problem. I replaced my battery terminal connections because they were all croded and that fixed the problem.