battery light - stays on until engine is revved

#1

anyone have any ideas as to why after starting the car, the battery light stays lit, but if the engine is revved, the light goes out and stays out?

#2

That would be a flaky alternator. If the bearings are still good a new voltage regulator may be all that’s needed.

#3

Voltage regulator/brush assembly to be completely correct.
It is the $25 way to rebuild an alternator. Replace the brushes with the alternator still in the car. Two flat blade screws hold the brushes in.

But, I don’t think that is the problem, 'cause my car does the same and has for 2 years.I bet that your ABS light is also on? With my car they both go out when it is revved. The battery is good, it holds a charge, and it starts the car, so I just keep on racing.

Regards,Robert (rev the engine) Patton

#4

Mine does the same thing. Brendan told me once about “exciting the alternator”

Whatever that means. I don’t like or understand electricity so maybe someone can run with that.

Doesn’t seem to hurt anything though.

-Also brandnew alternator and brand new battery so I don’t think that is the issue - at least for me.

#5

I’ve had a few Bosch equipped cars that have been like that. It doesn’t seem to hurt anything. I just learned to live with it.

#6

are there any fuses blown to any other circuits in the car?
I don’t know the complete details, but there is some signal that feeds the warning light, that causes it to stay lit if a particular fuse is blown, until the engine is rev’d and the alternator “self-excites” and back feeds to provide enough signal to make the light go out.

Another theory is that the alternator belt is slipping at idle until you rev the engine. I’d check/clean the ground connection to the alternator as well.
thanks,
bruce

kmsnsx wrote: