martik777

My bat light came on and I determined the alternator was bad. Haven't replaced yet but I noticed the bat light is no longer working, even on the bulb check position with the ignition key.

Question is, will the new alternator charge with a burnt out battery indicator bulb?

tech8

What year vehicle and model?

Yes, an alternator will still charge with a burnt out charge indicator bulb. There is the possibility the charge indicator LED is not burnt out though.

martik777

oops, 2003 accord 2.4l

I replaced the alternator and now the light is working as is the alternator. I guess the voltage regulator or diodes were causing the light not to work after about 100 miles.

Luckily I noticed the light before it went out.

tech8

Good to hear thing are okay now.

Generally, the voltage regulator sends a L signal ground (indicator lamp circuit) to the ECM/PCM, where the ECM/PCM would then provide the ground (-) to turn the charging indicator lamp ON. Power (+) to the charging indicator lamp comes from under-dash Fuse No. 21. When the alternator sends charging voltage to the ECM/PCM, it turns the charging indicator lamp OFF.

martik777

So, the old alternator voltage regulator was probably failing those last few miles? Brushes were moderately worn but I doubt that was the problem.

Thanks for the explanation.